Timeline to a Lunar Society

What matters is understanding what needs to happen, and what can happen. Then if people feel it is a goal worth pursuing, it happens. This page explains the best conceivable path if that will is there and pushes aside conflict politics. In that situation, from when the first mission launches, it would take about 50 years to get to the part called Birth of Worlds.

The path uses known technology, and a reasonable pace of development. Starting 25 years in, it assumes AI has advanced enough that robots can do complex work without supervision, and 35 years in, that good carbon nanotube cable is available on industrial scales. Those assumptions are conservative.

If we knew what amazing things we could achieve if only we worked together, perhaps we’d find the will to do so. What follows shows a world like that.



Transport Systems

The key to success

Europeans colonized the world thanks to their great sailing ships. Railroads were vital to expansion across the North American continent. Almost any level of investment is justified if it secures you access long-term to a large enough place. When that new place is the rest of the solar system? Bet the bank on it. The difference between reliance on chemical rockets and reliance on the system below is like the difference between wagon trains and steam locomotives. Railroads completely changed what was possible. What follows is the same thing.

The cost of transport is currently a high percentage of the total cost of space missions. Total loss of missions due to launch failure, engine failure in space, or landing failure is 5% to 10% of everything launched. Long delays due to the time it takes to prepare and launch rockets slows everything down. Any serious undertaking in space needs to address these issues before it does anything else. The road to profitability can be made much shorter with a proper transport system design.

Colony Development

Go big, go robotic

Our position is it doesn't make sense to undertake construction or any industrial process on the Moon unless it can be done by robots that are operated remotely, or that operate themselves. It will be difficult to get this right at first, but once achieved then the slow, grinding, linear growth of projects in space up to now - is gone. In its place is a growth curve steeper than anything we have ever known. So to contemplate the workings of such a system, you might as well model it on the Moon, where there are no immediate and rather alarming questions about the resulting unemployment, or environmental impact, or power shifts, or anything like that. The reason this timeline forecasts such dramatic growth is because the robots make a world of difference. Advances along these lines have been impressive recently. This is a future we have to expect.

Also, once a base is being built of lunar materials, it should be as big as possible. Most things should be made as large as they reasonably can be, until transport between Earth and the Moon has become routine and the colonies are very well established. Redundancy and extra capacity tend to come in handy at an outpost. Most of the businesses the colony will pursue first also tend to benefit from economies of scale - real estate development, heavy machinery manufacture, facilities for broadcasting, sports, research, and tourism.

Socio-Economic Development

A bridge to a new era

Everything here is predicated on the idea that a group of nations decide together to colonize the Moon and devote the funds necessary to do so properly without question. So, let the model be that the first missions are funded and carried out jointly by the nations with well-established space agencies - the United States, Russia, the European Union, China, India, Japan, and Canada. Once the Residence Program (explained below) begins, all nations participate.

This is, of course, the arena where Moonwards leaves reality aside. A case can be made that until we undertake something together on the scale imagined here, and thus establish a sense of common cause, the world will not have peace. If so, contemplating it is helpful to reaching such peace, however remote it is from the world we live in.

The rosy, cozy view envisioned below also maximizes the scope of activity the project can ponder. In many places it's even simply convenient for organizing people into groups within the virtual world. Please bear in mind it is deliberately Utopian for all these reasons, and is not meant to endorse any political policy in the real world.

Consequently, it doesn't make sense to predict exact schedules. The timelines below are rough estimates of duration and deliberately exclude exact start dates.

Phase 1 - Year 0 to Year 15

Construction of the Earth Equatorial Space Station

Because of the scale and nature of the work that happens on this station, it is built in an equatorial orbit. These orbits never pass through the South Atlantic Anomaly, so the radiation exposure of people on the station is a fraction of what crews on the ISS get. This architecture has been extensively explored by Al Globus et al.. The station is the proving grounds for tele-operated robotic construction. Successful development of that and cost savings from reusable launch vehicles allows creation of a space station on a much grander scale than the current International Space Station. Progress in AI, tele-robotics, and in-situ lunar resource processing allow later materials to be obtained from the Moon.

What the EESS includes
  • An area for on-orbit assembly of the ships that will go to the Moon (the Pod ships and the Lunar Nuclear Craft). This area is also the base for assembling the Station modules and components delivered from Earth. It is the first thing built - a hexagon of trusses all connected to a central module.
  • Aside from being the construction area, the hexagonal truss area is where automated ships berth, cargo pods are moored, and robots are stored. Bits and pieces get tacked onto it while things are being built or repaired, satellites or probes are being prepared for deployment, or equipment flying experiments do their work. We shall call it the Hexagon.
  • The Hub starts as the initial module at the center of the Hexagon and then grows outwards in one direction. Large tanks for water brought from the Moon, and equipment to crack it into hydrogen and oxygen, liquefy that, and store it until it is used to fill the fuel tanks of ships, is clustered around that module.
  • Further modules extending the Hub house all the key infrastructure for the Station - power conversion and distribution, cooling, air tanks, air scrubbers, airlocks and docks for crewed ships, tools, sensors, comms equipment, and initial crew quarters.
  • Then, a flattened Torus is added. It and the Hub are spun up to create a simulated gravity environment. The torus is large enough to accommodate both crew quarters and labs doing a range of research on low-gravity. It has several greenhouse spaces and sections for animal experiments. Its outer rim experiences centrifugal force equivalent to the gravity on Mars, while the top floor of its torus is like lunar gravity. The Hub contains a lab for micro-gravity experiments. The Hexagon does not rotate, it is counter-spun to keep it stationary relative to the Earth.
  • Finally, 4 Teardrops are added to the torus, spaced 90° apart, each across from one of the tubes going between the Torus and the Hub. The tips of their cones attach to the outside of the Torus. The shallow bowls at their other ends experience centrifugal force of nearly one gravity. This means crew would move regularly between environments with different levels of gravity. Over time, biomedical monitoring of the crew establishes how much time is needed in the varying levels of gravity for good health.
  • The solar panels need to be quite extensive for the Station to do its construction and processing work, and to supply the labs with all the power they need. They extend from the end of the hub opposite the hexagon of trusses, together with the radiator panels.
  • Many elements of the final components built, including internal elements of the Torus and the Teardrops, are made with materials from the Moon
  • Water and lunar dust from the Moon turn the greenhouses and animal habitats into complex micro-environments. This enables experiments in air and water purification with plants, creating fertile soil from the lunar dust, cultivation of a wide range of plants, and the adaptation of small animals to the small garden environments thus created.
Pod Ships start shuttling between Earth orbit and Lunar Orbit

The Pod ships are operated remotely. They are capable of doing rendezvous and docking maneuvers on their own. Basically they are a nose with all the operating systems, a robotic arm, and a pair of solar panel wings, then a long truss with racks for the pods, and then the fuel tanks and engines on the far end.

The pods are the space equivalent of shipping containers - standardized and mass-produced tubes with rounded ends covered in insulation and Whipple shielding, a sliding door, internal structures for storage, and connectors if items need power or a comms connection. A Pod ship can take 8 small pods or 4 long ones. Crew are transported in pods adapted for life support and basic accommodations. Some pods are water tanks, returning mined water from the Moon to the EESS. Pod ships are designed for a maximum payload of 80 tons to lunar orbit when operations begin.

Pod Ship Operations and Early Missions
  • These ships have next gen hydrolox engines capable of many restarts. They get serviced between trips at the EESS.
  • Early missions are all to a polar orbit. Once tether construction begins, they all enter a circular orbit over the Moon's terminator (between the night side and the day side), at an altitude of 5000 km. The skyhook complex goes there so that it has constant sunlight on its solar panels[?]. The two later polar skyhooks, spaced 60° in front of and behind Crossroads, both will too.
  • The 1st and 2nd missions deliver 2 Lunar Nuclear Craft, extra fuel, and initial equipment for surface operations.
  • Then there are 20 missions to deliver the equipment and components to build the first polar skyhook. The Pod ship that delivers the first of these stays in orbit so its solar arrays can power the construction equipment, plus it provides a comms link, orbital maintenance, and a stable construction platform. The other in operation at this point delivers materials and equipment every 2 weeks.
  • The first half dozen of these missions deploy several satellites each. First is a set of comms satellites so polar ops always has a radio link with Earth. The next three bring sets of observation satellites for imaging in high resolution and a suite of wavelengths, plus radar, lidar, and gravity mapping. The last two deploy a lunar GPS system
  • On the 3rd skyhook mission, a crew pod is dropped off and connected to the Pod ship staying in orbit, with a crew of 4 that stay for 4 weeks. They oversee initial deployment and testing of the skyhook construction equipment, and remotely operate equipment at the lunar pole. The 6th one delivers the superstructure of the future Crossroads Station, and the Pod ship leaves, handing off its duties to that skeletal Station. The role of the Station after this is outlined in its section below.
  • A few months after the start of lunar surface operations, ongoing missions commence to deliver fuel, equipment and materials which the LNCs transfer to polar ops.
  • By the end of this phase, the Pod ships have delivered many loads of equipment and supplies, and have rotated many crews. They return to the EESS carrying water, regolith and rock, and initial in situ processed materials for testing, and later, for incorporation into internal elements of the EESS.
Maintaining the orbit with this relationship to the terminator requires it be made to precess one revolution around the poles each year. Our estimate is that this requires a few meters per second of delta V each day, which fits easily into the fuel budget.
Lunar Nuclear Craft (LNCs, pronounced 'links')

These craft use nuclear thermal engines with a bipropellant design, known as a LANTR design. They get thrust by superheating hydrogen, and during launch and landing, can greatly augment that thrust by injecting oxygen into the engine nozzle, basically like an afterburner. They are designed for vertical landing and takeoff.

The LNCs are similar in architecture to the Pod ships, including being self-piloting. The difference is their engines are nuclear, which means they include heavy shielding, and they don't have solar panels, as they draw their electrical power from the nuclear reactor as well. Their racks have space for up to 4 small pods or 2 large ones. Thanks to their bipropellant capability, they are able to launch and land about 20 tons of payload even before there is a tether reducing the delta V required, though it takes a lot more fuel to do so. Once the tether is in place, they are designed to move loads up to 40 tons to and from the tether foot.

LNC Operations and Early Missions
  • Initially the LNCs help the surface rovers set up operations by providing supplemental power from their onboard reactors, acting as a comms link, and using their robotic arms
  • Once water production allows supplementing of their fuel supply, and the growing tether lowers delta V requirements, they shuttle loads of lunar rock to the tether foot. This is taken up to the tether anchor to increase its mass. They do this as often as possible.
  • With further increases in water production, they begin delivering tanks of water to the tether foot as well, as often as possible.
  • They do a series of sortie missions to the lunar maria and areas of interest, collecting samples for analysis and experimentation, and surveying.
  • Before people can be landed on the surface, a system needs to be constructed to keep them safe from the radiation of the LNC engines. A well is excavated in the LNC landing pad, so that before people exit the craft, the engine section is unclamped and lowered into it, eliminating the radiation hazard. This unclamping and lowering system must be built into the craft from the beginning, and should be used as soon as the well is built, though people won't arrive for a couple of years.
Crossroads Skyhook and Anchor Station Construction

Once the superstructure for Crossroads is delivered, it is continuously occupied by crews of 8, who stay for 4 weeks at a time. Further deliveries by the Pod ships build up its capacity, and the regolith that the LNCs send up establish good shielding. Once there is enough shielding over key areas such as sleeping berths, crews begin to extend their stays. By the end of this phase a crew of 12 is always aboard, and people stay for up to a year at a time.

The crew of Crossroads can operate the robots on the lunar surface, and on the skyhook, without the significant delay during transmissions from Earth which slows and complicates tele-operation. Much more complex and dynamic robotic work can be done in this situation. That is explained in the next section.

By the end of this phase, the lower tether is equipped with a foot platform that can berth a fully loaded LNC, a tip platform that can berth a fully loaded Pod ship, and climbers that can transfer the full payloads of both. This requires a total of 1000 tons of Zylon woven into a tubular mesh extending 5000 km downwards and another reaching 4500 km upwards, which can carry the load of the platforms, climbers, maintenance and motion control systems, berthed ships, and cargo, with a safety factor of 2. The foot platform is only 20 km above the lunar surface.

The complete skyhook allows the LNCs to reach the foot platform using one fifth of the delta V needed to reach orbit, and the Pod ships to break lunar orbit on an Earth trajectory with no fuel use at all - they just let go of the top of the tether. The fuel thus saved allows the Pod ships to haul 100 tons instead of 80.

Skyhook Systems and Operations
  • The climber cars run on power beamed as microwaves from the anchor station and from the foot platform. Onboard flywheel energy storage allows them to go short distances without receiving external power. There are 10 waystations along both tethers, where cars can pass each other, and where microwave receivers and transmitters pass power from either end of the tether up or down. Such receivers and transmitters can be very light, though some need to be large to be effective. The large ones can be mostly on the anchor station, where their mass doesn't matter.[?]
  • The waystations also make it easier for maintenance and stabilizer carts to shuttle along the tether checking and repairing its cables, and releasing and catching momentum-exchange weights. The waystations are places where the carts can recharge their flywheels (though they also have microwave receivers for power). At the waystations, the tether is stronger and more protected. Between waystations, there are a large number of separate tether sections that connect to each other by the cables of the one below looping through the mesh of the one above, and those points on each mesh being reinforced to sustain the bending stresses there.
  • The anchor station runs on solar power. Because the tether orbits near the terminator, the only time its solar arrays aren't in sunlight is during the occasional eclipse by the Earth. The solar arrays are extended over time as a wing extending from one side of the station.
  • Maintaining anchor altitude and a circular orbit is mostly achieved through passive momentum transfer, by dropping and retrieving weights. These weights are rocks massing a number of tons. They get larger as the skyhooks increase in capacity. When one is dropped from the lower tether high enough that it remains in orbit, the skyhook bobs upwards. When one is dropped from the upper tether low enough that it doesn't escape, the skyhook bobs downwards. Releasing weights can be done repeatedly so it completely compensates for any payload moving up and down the cables, without the weights eating up too much of the bearing capacity of the tethers.
  • Engines on the anchor, and on the tip platform, supplement this and do the work of precessing the anchor's orbit to keep it always in the same relationship to the sun. VASMIR drives, or Neumann drives, or maybe HiPEP drives - whatever wins the high-ISP race will do nicely. The engines on the tip platform provide the most momentum exchange per unit fuel. The engines on the anchor exist to provide more control. Both places also have a set of emergency thrusters for possible avoidance maneuvers or orbit correction in the extremely unlikely event of a cable being severed.
  • Because the foot platform is only 20 km from the surface, and moving quite slowly, it is a wonderful place to put cameras. It gets a bunch with nice huge lenses and a selection of filters, and radar and lidar units.
  • It is always best to have an anchor mass that is as heavy as possible. The more massive the anchor is compared to the spacecraft that use it, the less its orbit is affected as mass moves up and down the tethers. As resources allow, the anchor mass of Crossroads, and of all the skyhooks from here on, is added to, to maximize its mass.
An alternative is the climber cars run on nuclear power from a small reactor connected to Stirling engine generators. By putting the reactor in a separate car and running a power cable from there to the climber, the reactor can be kept a kilometer or more from the climber, allowing a shield with a smaller area to be used between the two. A shielded dock thus has to be made above the foot platform, so the climber can pass the reactor and reach its destination. A dock that is about 10 km from the anchor station is also needed, so the cone of shielded space is wide enough to cover the whole station, and anything that might stick out gets a weaker dose. Overall, the microwave beaming approach seems more flexible, more robust, and safer, as long as the beams can be kept well aligned despite oscillations due to actions on the tether. The transmitters would need to be able to rotate a small amount to keep receivers in their focus. Having flywheels to store energy as well thus is also interesting in that they can be used simultaneously to dampen oscillations. Energy harvested when climbers control descent by braking could also be used to spin up the flywheels. Perhaps calculations would show the flywheels would be too heavy to be a significant help, pending that it is just a thought.
EESS Fuel Depot and Reusable Upper Stages

Once ice mining is in full swing, a plan to refuel the upper stages of rockets going to the EESS is initiated. Once complete, all the rockets delivering to the EESS are almost fully reusable - both stages and the capsule or cargo pod[?]. This architecture would allow launch prices to drop by 80% to 90% from current levels, a critical goal if the high flight-rate lunar settlement requires is to be maintained.

Of course, the SpaceX BFR is designed to do that with no refueling. That could make this unnecessary, but probably even SpaceX would welcome the chance to refuel their upper stage so they can do lots more braking before it enters the atmosphere. That would save on wear and tear and maybe make it easier to build BFRs that aren't... quite so big...
  • Once the EESS is getting all its orbital maintenance fuel from the Moon, its orbit is lowered from about 400 km to 200 km. The increased atmospheric drag will mean more frequent boosts are needed to keep it at that altitude, but that is more than offset by the reduction in the fuel upper stages need to return to Earth from that lower altitude.
  • Since on the return trip these stages aren't pushing a heavy payload, they have enough fuel to decelerate to a full stop and do a soft landing. On the way up they were accelerated to 1.5 km/s or so by the first stage of the launch vehicle. On the way back, they have to brake that velocity themselves, plus all the additional speed from there to meeting the EESS. They might need a little extra fuel to brake that extra velocity while empty, over what was needed to get to the station with their payload. If so, their fuel tanks will have space for that fuel and be not quite full on the outward journey.
  • In fact, because the EESS has the Hexagon and a complement of robots, instead of jettisoning fairings, the payload section can be integrated into the stage, with doors that open for removing payload, a little bit like the Space Shuttle cargo bays. The whole thing returns intact and ready for quick reuse.
  • And in fact, it would be capable of returning a small payload if desired. At no extra cost.
Robot and Rover Mission

Each of the 2 LNCs delivers equipment to the base site on the west rim of Hinshelwood crater, near the north pole, each returning once to the Pod Ship to land it all. They land 80 tons of robots, equipment, and supplies, and enough water for the hydrolysis pod to produce the fuel needed for them to make it back to orbit. The robots are tele-operated from Earth at first. That work is around the clock, but because there is a transmission delay of about 3 seconds, work is slow and tedious, and the kinds of activities that are possible is limited. Once Crossroads has a crew, they start taking over the remote operation. More things can then be accomplished, and faster. Some operation is still done from Earth.

Initial tasks done by robots
  • Set up tall masts for solar panels and microwave power transmitters, cables and power management equipment, and radiator units. The rovers are powered by microwaves beamed to their rectennas, smaller mobile robots recharge frequently, including sometimes from the rovers. The solar panel masts rotate over the day to stay aligned with the sun. The Moon has a very minimal tilt to the sun, only 1.5° - at the poles the sun skirts the horizon all year and in high spots is almost never out of view. The base is in a spot that gets sun most of the time. With the added height the masts give the solar panels, they are in the sun almost constantly.
  • A half-pipe shaped hangar is set up on ground that has been roughly leveled and paved. It is an unpressurized shell with various snap-together units inside, creating a maintenance and repair hangar for the robots and their tools, and a lab area. All the equipment for these tasks in installed in the prefab bays designed for them.
  • One of the cargo pods lowered from a LNC is a self-contained unit for converting water to liquid oxygen and liquid hydrogen. It only needs power from the solar masts or the LNC reactors, and its custom radiator units deployed. It lands with a full water tank.
  • A rover using simple mirrors and Fresnel lenses fuses surface regolith around the site. The thin layer created will tend to break up and shift, but by driving a grid of fused regolith stakes into the ground before passing the lens over an area, the melted surface fuses with the stakes into one piece. Cracking then doesn't lead to shifting. Thickening the fused layer by spreading more regolith overtop and heating it is done in areas that call for it, such as the LNC landing pads.
  • These simple stakes are produced in graphite molds filled with molten regolith produced with a parabolic mirror setup. This method produces items with consistent and high quality and uniform shape.
  • Experimentation is done with making useful shapes by cast-in-place methods after pressing shapes into the powder regolith, and by scanning focused sunlight over a bed of powder regolith (known as melt-in-place). After a while, a method good enough for making simple construction materials is developed. Shapes are rather variable and soft-edged, and material properties are somewhat inconsistent, but they work.
  • Potential ice mining sites are scouted and surveyed. A large area is surveyed with ground-penetrating radar and seismic sensors, both within Hinshelwood Crater, and in surrounding depressions. Many cores are drilled out and taken for analysis in the lab.
  • Prototype equipment for ice mining is tested in shallow depressions that don't reach the unEarthly cold of the large northern craters, which are far more challenging environments and of much greater scientific interest.
  • A unit for boring deep holes is tested in a sunlit area. In the holes bored, small charges are laid and excavation by blasting is tested - far from everything else, and on a small scale.
  • The wells for the LNC nuclear engines are blasted out and prepped.
  • The LNCs conduct sortie missions scouting places of interest on the Moon and returning samples for testing in the lab.
Crew Sortie Mission and Robot Expansion

An initial hab for crew sorties that looks a lot like a Quonset hut (based on upcoming design by Benaroya et al.) is delivered and set up prior to the arrival of a crew of 4 that stays for 2 weeks. The LNCs deliver a further 100 tons of materials and supplies in support of the crew and accompanying mission goals.

Their work makes the robots about as agile and precise as people. They test and deploy the new equipment that arrived before their mission. Much of that equipment is prototype water mining robots. By the time they leave, the robots on the base are as capable as a permanent crew of around 30 people. They are assisted in their work by the crew on Crossroads Station, who operate the robots as the crew on the surface direct.

How the Crews Augment the Robots
  • They set up infrastructure that enhances the precision of the robots dramatically: rails, grids of sensors and signals, monitoring cameras. These are placed with precision the robots were not capable of.
  • They do any repairs that were beyond the abilities of the remotely operated repair bays, which mostly used drop-in replacement parts. They install and test equipment to give those repair bays abilities comparable to a human with a full workshop.
  • They deploy and test the next generation of robots, designed based on experience with the first generation. They do final assembly and calibration before putting them through their paces in a way that efficiently collects data for design of the 3rd generation.
  • They especially focus on deploying and testing several prototype water mining units, assessing them and adjusting them in a series of trials. This information is used to deploy the first generation of truly industrial equipment, after which water production becomes a real business.
  • They set up the guides and markers showing the robots where to excavate for the first permanent hab, and the production units for the construction materials that hab will be made of. They ensure the products from those stations meet quality standards and the construction robots are performing up to spec. Once satisfied, they give the green light for construction to commence.
Construction of First Hab at the Polar Base

This habitat is the first instance of the robots doing truly complex work. It isn't possible until the crew on Crossroads is able to control them finely, and count on them to execute a lot of complex behaviour with little to no direction (such as maintaining their balance, picking things up, throwing and catching things).

It also requires excavating a cube 30 m on a side, and mass production of simple construction materials with consistent quality (though that quality doesn't have to be high). The outer walls and the internal floors and walls are made with local materials. Furnishings and utensils are also locally made (shelves, tables, doors, chairs, beds, dishware, hand tools).

Construction Process
  • In-situ cast-in-place and melt-in-place techniques are sufficient to supply rods, boards, panels, blocks, and beams. Joining and sealing is done by adding molten regolith or melting things together, so uniformity is unimportant. Inconsistent strength is compensated for by using more material. The stakes, which are higher quality, anchor everything to the surrounding hardpan regolith.
  • Excavation methods rely largely on 'blasting', done with micro-charges just large enough to loosen the soil, keeping flying debris to a minimum. The are laid in grids of bore-holes. As the pit is deep, the vertical faces of it, which become the hab's exterior walls, are allowed to slant inwards 10° or so. Hardpan regolith packs so cohesively, a face with that slant is stable even at 30 m tall.
    • The faces and floor of the pit are shaped with heat-based cutting methods, that use focused sun, microwave emitters, and lasers. There aren't many yet so shapes are kept simple.
    • Undercuts are dug out with ripper and jack-hammer attachments on the arms of heavy-duty construction rovers. They use ballast and attach cables to anchor points sunk into the pit floor so they have the stability necessary to yank hard on things without tipping.
  • With shapes roughed in, stakes are sunk into the walls and ceilings in dense grids. Panels and boards of fused regolith are attached to the stakes and parged into solid surfaces using molten regolith. Floors are levelled and sealed by pouring molten regolith over them.

Everything else is shipped in, but it takes only one Pod ship payload to deliver it all. Large items include a second hab with an extra large airlock, the tubes and mirrors of the light funnels, the multi-layer transparent membrane roof and its reinforcing cables, and several very large high-resolution computer screens. Other major items include radiators, a water treatment plant, and air scrubbers.

If assistance from the crew at Crossroads is required, they can fly in for a week at a time and stay in the hab. The aim would be very much to avoid that, perhaps there might be one or two such trips. Once the robots have finished construction, a crew flies in to confirm it is all sound. The hab's systems would already have been checked remotely, and the structure pressurized, but the crew does a thorough check on-site.

With the all-clear given, the hab is stocked and its first crew of 40 people is flown in.

Water Production

Once a successful approach to ice mining is found, 200 tons of equipment is brought in to do just that. Initial caution to preserve the permanently shadowed regions for research is abandoned in Hinshelwood Crater and Hermite A Crater. They become ice mines. This opens the possibility of using techniques that are much more disruptive, but get ever more efficient with scale. One possibility is covering a large area with a strong membrane and sealing it to the ground, putting a heater in the center of it, and pumping off any gases released by the heat.

With this industrial approach and the cargo capacity of the transport system, water production ramps up very quickly. Accompanying production of carbon dioxide, ammonia, and several trace gases is also significant for lunar development. Production exceeds 10 kilotons per year within 5 years, if reserves are at the low end of predictions.

This means that all the fuel for the Pod ships, the LNCs, the EESS, and other spacecraft fueling at the EESS then comes from the Moon.

Creation of the International Space Agency

The agencies of most of the major space-faring nations cooperated in the construction of the International Space Station: ESA, JAXA, Roscosmos, NASA, and CSA. This is the best precedent but is a minor collaboration compared to what would be involved in settling the Moon.

So the ISA is created and has its own staff, taken from all the member agencies. The founders are the United States, Russia, China, the European Union, India, Japan, and Canada. The agency creates the overall plan and parcels out the work on it. As the United States remains the country with the largest space industry and the most launch facilities, it is headquartered in Florida not far from Kennedy Space Center.

The construction of the EESS serves as the test case for settling questions of jurisdiction, ownership, information sharing, and legal responsibility. Again the agreements covering the ISS are the model that would need to be built on.

A shift to an open-source model regarding sharing of the technology developed for the project reduces tensions on several of those issues. A treaty is drawn up for the rest.

As the project would be underway for a number of years before it involved a permanent human settlement, and a number of years more before there was profit, the scale of cooperation needed to continue working together can ramp up at a manageable pace. A limited-time amendment mechanism for the treaty is used to refine it during its first decade or two of existence.

The endeavor provides a model for international cooperation that can be applied in many other areas. The sense of shared goals that comes with the undertaking supports the growth of international goodwill.

Status by the end of this phase:
  • the Pod ships have made around 100 trips to lunar orbit, most of them carrying crew for Crossroads.
  • The last trips bring crew for First Hab at the polar base, now dubbed Inukshuk Colony[?].
  • First Hab is a permanent structure that houses 40 crew from the ISA nations. That crew is composed of married couples on extended missions of at least 5 years.
  • The ice mines are producing 20 kilotons of water per year. This water supplies all the fuel for the LNCs, the Pod Ships, and the EESS. It has been used to augment the shielding of Crossroads Station and First Hab, and to supply a large fuel depot at the EESS.
  • There were about 200 to 250 launches from Earth lifting a total of 6 kilotons of payload to accomplish all this - an average of 13 to 17 launches per year.
  • The ISA nations have withdrawn from the Outer Space Treaty and signed a new Space Settlement Treaty (SST) governing their actions in space. That treaty evolved from the agreements they set up to cover the EESS and their joint lunar ventures, including the amendments that were enacted over the course of this phase.
While the crew tested the upgraded and new robots on their first sortie at the polar base, they used them to construct several inukshuks - stacks of balanced stones traditionally used as landmarks among Arctic peoples. They made one particularly large one, liked it, and left it standing. Thus the colony acquired its name.

Phase 2 - Year 16 to Year 25. Residence Program Round 1.

Gagarin Skyhook and Anchor Station

This process is a repeat of building Crossroads, except much faster, and much bigger. At least, Gagarin is set up from the outset to grow into the future shipyard, full orbital colony, and manufacturing center it will later be. The superstructure delivered from the EESS is much larger, as is its wing of solar panels. The deployment of the cables, cars, and all its parts goes faster the second time around. The LNCs on the surface begin sending up full loads of regolith, rock, and water that add anchoring mass to the station, as soon as the lower tether is close to its full length. No pressurized sections are added yet to Gagarin. Activity there is entirely conducted by robots controlled from Inukshuk and Crossroads.

Because it is in an equatorial orbit, ships can launch from it or dock with it at any time of the month (Crossroads is only properly aligned for that twice a month). Another important new feature of Gagarin is that its upper tether extends to 17500 km above the lunar surface. At that altitude, the outward velocity imparted to a vessel hanging on to it is enough to fling it all the way to Venus, or Mars. All that has to be done is to detach from the cable at the right moment.

Expansion of Crossroads Skyhook

The solar array wing of Crossroads is greatly expanded, in preparation for beaming of power to Lalande Crater for upcoming construction (which Gagarin also will do). The Station is upgraded and expanded to accommodate a crew of 50 who stay for terms of 1 to 5 years. It gets a centrifuge so that they can do so without risk to their health.

Gagarin and Crossroads Operations
  • Some materials sent up from the surface now are actual structures fabricated at the colony. Their materials are fairly crude, but they are sturdy because weight doesn't really matter - making the anchor heavy is part of the goal. Thus they are strong enough to do their jobs. Pressure vessels, tanks, and trusses are sent up and added to the stations.
  • The tethers of Gagarin are upgraded throughout this period to handle ever greater loads. By the end of it both its upper and lower tethers can handle up to 200 tons of material at a time.
  • Both skyhooks spend more time ferrying LNCs around the Moon, as there are now many missions to different spots on its surface: mining iron deposits in the central peaks of two craters, exploring lava tubes, volcanic regions, the south pole, and the far side, including setting up a radio telescope.
Lunar Fleet Expansion

The Pod ship and LNC fleet is expanded to support construction of Gagarin and Sagan skyhooks, and greatly increased sortie missions. Four Pod ships ply the route to the Moon, 2 meeting Crossroads and 2 going to the equator to build Gagarin, and then Sagan. These two then do Gagarin's transport runs. They are larger - they can break Earth orbit carrying 250 tons. The LNC fleet increases to six. Four LNCs support Inukshuk, including sortie missions to other parts of the Moon and delivering fuel to the two LNCs working on what will be Gagarin Skyhook. Those two LNCs are larger, capable of flying 60 ton payloads to the foot of Gagarin once it is commissioned. One of the Inukshuk LNCs is fitted with a dome-shaped radiation shield around its nuclear engines, so that human crews can use it for sorties without excessive radiation exposure.

A new class of ship is also created - Hopper ships. These ships transfer cargo between skyhooks, avoiding the inefficiency of sending something down a tether to a LNC, which than takes it to the destination tether, whose climber takes it up to that station. Hoppers instead climb a little up the upper tether of their skyhook and let go, so that at the top of the arc of their orbit, they can do the plane change that puts them on course to rendezvous with the anchor station of the destination skyhook, or a waystation platform part way along the upper tether. They use ordinary hydrolox engines, like the Pod ships, and can transfer up to 5 tons this way. They aren't capable of landing on the Moon's surface.

The Fetch ships also make their debut in the Lunar Fleet, but they deserve their own section

Day of the Asteroid Fetchers

The hunt for near-Earth asteroids (NEAs) is on, using the 3 Fetcher spacecraft maintained at the ready, berthed at waystations on Gagarin's upper tether. They are sent along the upper tethers and released at the altitude and moment that puts them on the best available trajectory to whatever opportune NEA is detected. The speed and trajectory imparted on release leave these craft with more fuel available for pushing the asteroid into a trajectory back to lunar orbit. They have VASIMR engines powered by solar panels and fueled by hydrogen. Their fuel tanks are filled just before launch from larger cryogenic tanks set up at the waystations. These storage tanks are well-sheltered from solar heat by cones of specialized multi-layer insulation and have their own cryogenic chilling mechanisms to reduce losses due to boil-off.

The craft use the SHEPHERD approach of enveloping the NEA. In this method, a giant open bag is positioned around the asteroid and then its end is drawn closed. The bag is filled with a thin atmosphere of xenon gas. The asteroid's spin and tumble stirs this gas. The turbulence this produces slowly dissipates the energy of that motion, until the asteroid comes to a halt. In this way, the many asteroids that are very fragile don't disintegrate. They are returned in their original state, allowing us to study their structure. The bags on these Fetchers can surround an object up to 20 m across. If the trajectory of the NEA is fortuitous, the Fetchers can return an asteroid of up to 3 kilotons.

How to Catch an Asteroid

Gagarin's tip platform is equipped with telescopes specialized to search for just such targets, which are largely unknown objects detected only when they are very close. Two such telescopes slung under the platform, on bases that isolate them from its motions, scan the sky constantly for tiny, dim NEAs. They identify targets automatically, compute their parameters, and send in the information to the anchor station. By the time a human is alerted, the station's computers have plotted a rendezvous trajectory and possibly even a Fetcher ship is being prepped. It is possible with such tiny objects that the window of opportunity is soon and brief. Even with the optimized telescopes, a good target might become visible only hours before its closest approach - especially the dark ones bearing one to two percent precious carbon. The crew only has to approve the launch, and a Fetcher will take off by itself and do the rest.

Once caught and marshalled, the Fetcher slowly pushes the asteroid into a high lunar or Earth orbit. Once in orbit, a Pod ship hauls it in the rest of the way and berths it at Sagan Skyhook. This saves a lot of time, as low-thrust engines like the VASIMRs can only spiral in towards a world very slowly.

Done with that trip, the Hoppers ferry the Fetchers back to Gagarin, and they take up their station again. Once we get the hang of this, the Fetchers are upgraded for even bigger catches.

First Captured Asteroids

By the end of this phase, there are 10 asteroids berthed at Sagan Station. 6 are carbonaceous, 3 are stony, and one is metal. The total mass returned is 20 kilotons.

Sagan Skyhook and Telescope

The third skyhook is not for shipping things to space. Its main purpose is research. It has two major research projects. First, when Pod ships come in with a bagged asteroid, they gently pull into the anchor station, which has specialized berths for just this situation. Here, the asteroid can be studied over time in detail without other station operations getting in the way, as they likely would on the busy stations at Crossroads and Gagarin. Sagan has berths for 20 asteroids of up to 50 m across.

This easy-going situation for collected asteroids won't last, though. Once an asteroid has been thoroughly studied, unless it is very special indeed, it gets mined. A few fragments and lots of samples are preserved for ongoing study, and history. Of the minded material, what doesn't go down the tether is sent by the Hoppers to Gagarin for the shipyard and factories. Eventually, when Gagarin is more mature, it will make more sense to ship asteroids directly to Gagarin. Then Sagan's asteroid docks will be converted for other research purposes best done on an isolated, specialized station.

Sagan also has a giant telescope fitted on its tip platform that would make the James Webb blush. It is carefully isolated from motions transmitted up the tether and very well shielded from heat and electromagnetic noise. The tether allows it to be easily serviced and upgraded over time, and also allows it to be huge and heavy while remaining agile.

Incidentally, Sagan is also around so that LNCs hitching a ride can get to any given spot on the Moon once a week, instead of once every two weeks. Its foot platform can grapple and hold hitchhiking LNCs, but cargo doesn't go up its tether, only down. So its climber car is stripped down as it needs much less power. It can lower 40 tons but can lift only 1 ton, which it does on solar power and energy stored from the descent in batteries. No power is beamed along the tether, its maintenance carts get around on power from their own solar panels, and work at a leisurely pace.

Expansion of the EESS

A second, larger spinning section is added to the EESS, this time made mostly of lunar materials, including some structural elements. It looks sort of like a spinning top. Engineering of equipment for the Moon is now done mostly on the EESS, in a ring section open to vacuum extending from the first torus, spinning at lunar gravity levels, parts of it carpeted with a layer of genuine lunar regolith to imitate the Moon's surface. The Hexagon is extended to have several levels. Modules within it develop microgravity and vacuum manufacturing.

Space Tug and Space Debris Cleanup Services

The Pod ships have already occasionally been doing extra missions between runs to the Moon. They have delivered satellites to GEO and removed old satellites from the graveyard orbit above it, and deorbited a number of the largest pieces of space debris, lowering risk of collisions in orbit. However, the Pod ships are not made for this. After a while it makes sense to build specialized spacecraft for these tasks, ones without the Pod ships' giant engines and great length, with tools adapted to their tasks.

The amount of fuel the EESS can now supply allows it to host a space tug. The tug hauls satellites meant for other orbits from the station to where they are going. Then the tug returns and refuels for more work. It can haul 2 tons to GEO.

A small fleet of debris cleaners is also set up. They have VASIMR drives so they can do more before needing refueling and last a long time. They continue to hunt down the large pieces of debris and set them up for deorbit. They attach large balloons to the debris and inflate them before moving on. The balloons vastly increase the atmospheric drag on the debris, which causes them to slow and thus sink. Sometimes they move them into a lower orbit first, where there is more drag to do the job.

Draining the Inner Van Allen Belt and Changing Station Inclination

The EESS orbits directly above the equator in order to avoid the South Atlantic Anomaly. To make the station easier to launch to, and a better platform for Earth observation, it is decided to incline its orbit to 30°. In order to prevent radiation from the Anomaly then greatly increasing the radiation dose on the EESS, a decision is taken. Drain the belt.

This was initially proposed by Russian physicist Valentin Danilov. The concept was further developed by Robert Hoyt and Robert Forward into the HiVOLT system. It uses a set of conductive tethers anchored to satellites orbiting in the belt, to bend the trajectories of charged particles such that they escape it and leave. Their analysis showed an initial system of 5 satellites with tethers 100 km long would reduce the ionizing particles in the belt to less than 1% of the current flux within two months. A system like this is deployed, and further similar tethers added. In two years the belt becomes almost indistinguishable from surrounding space.

By the end of this phase a similar system is deployed for the outer belt as well. As it is much larger and more diffuse, the effect is not as dramatic. Still, over a few years the outer belt's particle flux drops by about a factor of 20.

Long Hab

Long Hab is a long, deep habitat with a vaulted roof. Like all habs in this mission architecture, it has plenty of natural light and big outdoor views. Its views are achieved with mirrors and lenses, so that radiation is kept low and the structural challenges of large windows are avoided.

Enough equipment, crew, and knowledge have built up for Long Hab to be a big step up from First Hab. It is 200 m long, 30 m wide, with variable depth of 30 to 50 m from the floor to where the walls meet the roof, and the vaulted ceiling is 15 m high.

Tele-operation of the robots building Long Hab is done by the crew of First Hab with support by the crew of Crossroads. Little tele-operation is done from Earth for construction. It is also uncommon for astronauts to work outside on construction, instead they do most things remotely through the robots. When they go out, they put pressurized cabs on the rovers and wear only flight suits, not proper space suits. Space suits are very restrictive, uncomfortable, and clumsy, they are used only when necessary (and occasionally just to go for a walk outside).

Construction Process
  • In-situ construction materials and techniques have developed enough that nothing structural is brought from Earth for Long Hab, and even some systems installations are made of local materials.
  • Excavation methods have matured enough that vertical walls of great height, deep undercuts, and tunnels of 50 or 60 meters are not a problem.
    • Blasting is used to make shaped pits and channels. Their sides are then made smooth and vertical by paring down lumps with heat-based cutting methods. The colony now has many such tools on a range of scales. Hollow bits are boarded over and packed with regolith.
    • Ripper and jack-hammer attachments on the arms of heavy-duty construction rovers still do rough shaping of recesses and undercuts. After that, specialized liquid-cooled saw blades and drill bits allow cuts to be made and holes to be drilled. Heat from friction would build up in the vacuum environment and make blades and bits seize if they weren't cooled. The bulk of the cooling systems make the them thick, they can't cut or drill anything narrower than 3 cm across.
  • The arches that form the vaulted roof are made of blocks from the first full MIP stations - melt-in-place stations, that evolved from earlier processes of that kind. There are also now many graphite molds, and molten regolith is produced in bulk for them, and for pouring into forms for large pieces. The roof is reinforced with basalt fiber cables from new production facilities making basalt fiber products on-site. Good basalt feedstock for the process is brought by LNCs returning from sorties where they had access to it.
Hab Architecture

The astronauts don't get to spend much time outside, and they are never truly outside. When on the open surface they are surrounded by beautiful desolation that can't fill in for the outdoors on Earth. Their indoors has to be their outdoors too. This is one reason why it is so important to make the habs as huge as possible from the outset. It is a matter of emotional health, and that becomes more important with each passing month of a person's stay.

The habs are also all huge because many things about regulating an environment in space become easier with size: thermal regulation, air recycling, air quality, noise control, and everything having to do with creating and balancing an ecosystem, from mold not growing on every surface where it has the slightest chance, to there simply being enough space for a complex set of organisms to coexist in something resembling harmony.

Thanks to the materials the habs are built from, and the way they are melded together, surfaces are never quite straight or flat and corners are soft. Once the molten regolith parged over the walls and ceilings has cooled into a single glassy surface, it will naturally have variations in tone and texture, and many simple things can help that along to accentuate the richness of the final patina. Not only is the building technique the best way to make use of the local materials, it is the best way to create a space that feels like you are in nature, though you aren't. This will be important to the residents.

Functional Features
  • Light tubes terminating in lenses - similar to the light tubes shown on the initial model of First Hab, these tubes funnel in a large amount of sun, and can do so most of the time at Inukshuk's location. In this version, the lens at the mouth inside the hab disperses the sun over a wide enough area for it to have the intensity of sun near sunset, with the spectrum of sun at noon.
  • Sky-like sections - A thin layer of molten aluminum is sputtered over these sections of the vaulted ceiling, leaving a surface that creates scattered, mottled reflections. This creates a sense of space above and distributes light more evenly. This is done in the sections with the light tubes, of which there are three along the length of the hab, interspersed with Earth-view sections.
  • Earth View Sections - There are four of these sections, and each has a large view of the Earth set up. Lenses are used to funnel that view through small gaps in the regolith overlay protecting the hab from radiation. Specifically, concave mirrors are placed to reflect the view of Earth through those lenses, which pass it to other large mirrors placed against the slope of the ceiling opposite. This way, there is a bright, clear view of the Earth visible in those mirrors, magnified by about a factor of 3. Because the Moon is tidally locked with the Earth, the Earth only moves around in its sky within a small circle about 15° across. At the colony site, the Earth is below the horizon for part of each month. When it is in the sky though, the residents have a gorgeous view.
  • Passive thermal control - A narrow channel down the center of the hab reaches bedrock. The bottom of the deepest section does too. Heat diffuses very slowly through regolith. It moves much faster through rock, and rock is also decent thermal mass. The surface area of the hab that is fused with bedrock is tailored such that the incoming heat from sunlight balances the heat moving outwards through that rock. Well-placed fans that keep the air circulating well is all that is needed to maintain a very steady, comfortable temperature.
  • Tunnel to First Hab - About 40 m separates First Hab and Long Hab. The two are connected by a small tunnel near the surface, actually a channel that was cut and then covered over. One end has an emergency door that will slam shut if there is a big change in air pressure on either side, just in case of an extremely unlikely disaster. Stored air can compensate for pretty big leaks long enough for an emergency patch to be made, or for people to take shelter in the airlocks if it's really bad. Only extremely rapid decompression would cause the door to close, in which case whoever is on the other side is out of luck.
  • The Larder, the Fridge, and the Freezer - Branching off from this tunnel are three pits with silos inside them. The silos contain a normal atmosphere and are entered through insulated doors. Sunlight never reaches the inside of these pits. They were dug such that once the silos were set down inside them, about a meter of space remained between the sides of the pit and their walls, and they sit on stilts. On top of their domes are radiator units. It's very easy to keep these silos cold. One is kept cool, for long-term storage of things like potatoes, onions, and apples. One is cold, for storage of perishables like cheese and fruit. One is below freezing, for meat and fish, and for freezing the ice packs for the coolers widely used elsewhere in the habs. There are often reasons to store other things at one of these temperatures, the silos store a mish-mash of items. Each silo is 8 m across and 12 m tall. At first they are mostly empty, they are sized in consideration of future growth, especially for the Greenhouses coming online.
Layout Features
  • Gardens - Each sky section is filled with as much vegetation as possible. About half is grown hydroponically, the other half is grown in soil, as that soil slowly accumulates. The work done at the EESS on beneficiating regolith into fertile soil has had success. The EESS sends back a couple of tons of the stuff and the recipe for making it. In place of organic matter to fluff it so it's properly aerated, they mix in perlite made on-site by foaming molten rock with compressed air. This soil is placed in several long, narrow beds, where the crew plant a variety of test plants, including a few bushes. In time, all the designated beds and planters are filled with soil, which is then slowly made deeper. As it is the soil that is the key to creating a true ecosystem, and those gardens that give the feeling of the presence of nature, the large ones at the bottom of the sky sections are planted with the widest possible range of plants. Each one has two or three small fruit trees, a number of bushes, vines climbing the walls, vegetable beds, flower and grass beds, and cacti.
  • Pond - The pool water (see Health, below) is pumped to a pond in one of the sky sections, that is planted with a range of aquatic plants. It is important for ecosystem creation to figure out how to purify water with natural processes. It takes a while before the crew manages to get the pond environment going. For a long time the pool water is mostly purified with filters and ultraviolet light disinfection systems. Slowly the pond becomes healthy and takes over the job.
  • Lunar parkour - The exertion of normal activities on Earth is absent on the Moon, if they are done in the same way. Designing the hab interior to take account of this allows residents to move in a way that is more efficient, more engaging, and healthier. Instead of stairs, tubes are used to move between floors, where you grab the sides and haul yourself up. With practise, residents learn to do this so fast it is a sort of vertical running. People often jump between floors as well. It becomes a passtime to find new and exciting ways to move around the habs by bouncing off walls, swinging from things, and jumping great distances. Things are placed to create opportunities for this. Each level of the hab is also high, 4 to 5 m, to give people headroom even though a normal moon walk has a pretty high bounce in it.
  • Health Facilities
    • Swimming Pool - With the ice mines producing lots of water, this is a full olympic sized pool with a deep end deep enough for high-diving. Swimming is an important conditioning exercise for residents - it loads their muscles in a way that is hard to achieve outside the water, making them work as hard as they have to on Earth to do the same thing, a consistent load that can be gentle or quite demanding. It is a central part of their cardio and muscle-building routines.
    • Manual centrifuge - this looks sort of like a wide bicycle wheel on its side whose axle is connected to a platform where people can spin the wheel using pure muscle power. It takes a while to get going but can then be maintained fairly easily at an RPM that imitates 1 gravity of force for the people on the rim of the wheel. Spending time frequently in this simulated gravity is important for the health of the residents - for their circulatory systems, and fluid distribution in their bodies, and the health of their bones. It’s unknown how much time a person would need to spend in this simulated gravity. Doing exercise on it would maximize its benefit to bone and circulatory health. The exercise of pushing the wheel is also beneficial. In this case it is designed to have a social element in that some push while others ride, a method suitable for something that takes an hour or so. A motor can also be used to turn the wheel. If in the long term other health effects due to low gravity can only be corrected by more extended time in simulated gravity, larger centrifuges designed for longer periods on the wheel will be needed. The body may need extended time there for more subtle corrections to the effects of low gravity. If more than 2 or 3 hours a day is needed long-term, more complex centrifuges than this will be needed.
    • Lunar gym - The gym area is the full height of Long Hab's tallest section, 50 m. Its floor is so heavily padded that even if someone jumps from the very top if it, they will land unharmed. The foam used is stiff enough that in the low gravity it can be walked over fairly normally, but yields sufficiently to absorb the energy of a jump from 50 m. Sections of the floor are trampolines, for rebounding back up over that distance. The padded walls are covered with small ledges and recesses for hand and foot holds. There are a bunch of ropes and nets hanging from ceiling to floor. The reason for all this is that in lunar gravity to get a decent workout, and to load as many bones and muscles as possible, the thing to do is climb. To put your skeleton through the forces it handles on Earth, the best thing is to jump high. It's also pretty fun to be able to jump up and down from so high safely. The residents quickly start inventing vertically oriented sports and games.
    Infrastructure Upgrades
    • The solar panel masts are expanded to provide more power, more of the time. They are made taller and wider, and the panels are moved up the mast, so they are all on the top half.
    • A large rectenna grid is set up to receive power beamed from Crossroads and Sagan when they are in range. The skyhook solar wings are always in the sun. To be well aligned with the skyhook's transmitters, the rectenna disc has to be able to both rotate and tilt. It is on an axle supported by towers that turn on tracks around a circular base. Grid-type rectennas are very light, in the lunar environment it is not hard to make this unit 200 m on a side. The transmitters on the skyhooks are much larger again. After this point, beamed power provides a large fraction of the colony's needs.
    • Large unpressurized hangars are built. They are half-pipe shapes on a levelled platform that has been covered with a slab of fused regolith. A shallow overlay of about 30 cm of powder regolith protects them from most radiation, and the heat of the sun. The interior temperature stabilizes at the average ground temperature of about -20 °C, which is a perfectly comfortable environment for machinery. This provides lots of space for manufacturing activities - dust free, stable temperatures, and free of radiation (except for cosmic radiation). A covered pit within each hangar provides some space for processes that require protection from cosmic radiation, as well, and storage space.
    • There are also similar hangars that hold a very thin atmosphere of about 5% Earth's atmosphere. These are for processes that need to shed a lot of heat. Basalt fiber production is the best example. Even a very thin atmosphere can transmit heat as well as a full atmosphere, the trick is to circulate it so that the heat picked up is quickly transferred to a heat sink, and from there can be radiated away. The stone slab floor has pipes that circulate heat to radiators in a trench just outside the hangar, along one side of it.
    • In both these cases, these structures are much like hangars on Earth in that they have large spans uninterrupted by any columns or other internal divisions, very large doors, and are covered by an arched roof.
    First Greenhouse

    The greenhouse is divided into two halves, making it more like two connected greenhouses. When it is night in one half, it is day in the other. This way, the colony's access to constant sun can be used to double output. To do this, the outlet of the light tube that delivers sun to the interior of the greenhouse pours that light onto a slanted mirror that bounces it onto the aluminum-coated greenhouse roof, which scatters it over the plants on the walls and floor. The light is spread enough to dilute it for maximum yield of the widest range of plants - even plants that like full sun are happy with sun that is about 2/3 the strength of sunlight on Earth, and sun on the Moon is about 30% stronger than that. That spreading also makes it only very weakly directional, it is more like sun through frosted glass.

    The greenhouse is two round pits surrounded by berms, with sloping walls and circular floors. They are each covered by a shallow, solid stone dome held down by basalt cables, which has a few meters of regolith on top. These domes overlap by about a sixth of their diameter, and in the middle of that overlap is the light tube with its big parabolic mirror on top funneling a ton of light down into the greenhouse as it tracks the sun. A passage between the two sides inside the structure holds the mirror that bounces that light to the domes. That mirror holds position for 12 hours, then it rotates and holds position for another 12 hours. Each dome is 100 m across. From floor to the top of the slope is a height of 20 m, and the dome rises 20 m more.

    Below the level of the mirror, the passage widens, and a hall off one side terminates in a work room. That workroom is connected to a hall going to Long Hab.

    The two halves of the greenhouse have very different projects. One side is focused on food crops, including raising insect crops for protein. The other side is focused on ecosystem research - searching for the combination of plants and animals that will establish a network of relationships that support each other, so the ecosystem is stable without intervention. Because the populations inside that half need to be monitored carefully, it is isolated from the other side, as much as possible. The mirror setup is built to remain sealed from the other side when it turns, the passage can only be reached by going through two doors with tight seals around them. It doesn't stop transmission of micro-organisms or spores, but it makes the picture of the dynamics within that greenhouse easier to see. A few animals have already been successfully brought to the Moon - earthworms, a few pollinating insects, small fish. This greenhouse gets a much larger set.

    As the atmosphere of the colony is custom designed, a higher proportion of carbon dioxide is established in it, to accentuate plant growth. It is set at 0.2%, or 2000 ppm, 5 times the current level on Earth. This is low enough to have no impact on the health of the crew, and is a feast for the plants.

    Research into Basic Industry

    Working with molten regolith of various sorts has been developed pretty far. They can make fabric and rope out of basalt, and a wide range of stone and glassy objects[?] and materials, some reinforced with glass fibers. These materials fulfill almost all structural needs well. The priority at this point is to develop local processes for producing the other building blocks of an industrial society out of local materials. Some things will take time, certain things can make a big difference in the short term.

    Technically speaking, a glass is any solid with an amorphous structure at the molecular level, which is to say, not crystalline. Many of the materials made before this out of molten regolith will have that quality, and quite possibly be very strong for that reason. It has been theorized that the ability to produce glassy materials in a completely anhydrous environment - that is, devoid of water - will mean the resulting glasses are far stronger than glass on Earth. Earthly glass is full of microscopic flaws due to its trace water content. If a glass with a higher melting point is spun into fiber, and those fibers are mixed or pressed into a glass with a lower melting point, the composites produced could have good strength in tension, compression, and bending.
    • Metal - The colony has 3d printers that create complex solid objects out of metal powders. Those powders are shipped from Earth. With the mining of high-purity iron ore in the peaks of a particular crater (mixed with nickel, a touch of cobalt and traces of other metals typical of metal asteroids) the colony works on smelters to purify that ore in bulk into each of its component metals. Dust roaster units, that super-heat regolith into plasma and separate the component metals by electromagnetic deflection, are also brought from Earth and deployed. Use of metal is avoided unless there is no good alternative. The amounts the colony needs at this point are easily supplied from Earth, but this research is important for the future. Especially important is aluminum for mirrors and electrical wire, and silicon for solar cells and transistors.
    • Carbon - On the Moon, you can't have too much carbon. In preparation for the retrieval of carbonaceous asteroids that will provide carbon, research is done on processes adapted to the lunar environment to create the following products:
      • Topsoil - is about 8% carbon, bound in organic molecules. To create enough soil to create a true ecosystem will take many kilotons of carbon. That carbon must be combined with hydrogen and oxygen to form complex organic molecules, such as sugars. Sugars get eaten by micro-organisms and animals, converted to other organic molecules, and it is at that point the carbon becomes part of the biosphere. Reactors that will form sugars from water and carbon minerals are developed. Alternatively, a special greenhouse with an atmosphere as high in carbon dioxide as the hardiest, most carbon-dioxide-loving plant will thrive in could be used to fix carbon in organic molecules.
      • Polymers - Zylon, the material proposed for the skyhook cables, is mostly carbon. Many plastics contain carbon.
      • Steel - is up to 2% carbon. Plain iron is not very strong. Although iron is very common in many parts of the Moon and is by far the easies metal to purify there, unless carbon is added to it, its usefulness is limited. Although lunar glass composites can be used for many structural applications, and mass on the Moon is not much of an issue, being able to make certain components out of steel will probably be helpful.
      • Explosives - Digging is way too slow and difficult on the Moon. In a place with no environment to damage, why dig? If you can blast, you should blast. Just remember there is no air to slow down the debris, so best to use many small charges to limit the range and velocity of the flying shrapnel caused by explosions. Having plenty of local explosives makes things easier.
      • Chemical processes - carbothermal reactors can be used to extract pure metals from metal oxides. On the Moon, it would be attractive to use this process to purify silicon, magnesium, calcium, and aluminium. Usually, pure carbon is heated with a metal oxide to a few hundred degrees Celsius, and carbon monoxide or carbon dioxide is produced along with the metal. Carbon is so precious, it would be critical to capture and reprocess virtually all of the gases produced.
    • Silicone - is a class of polymers that in many cases do not include carbon in their formula. Production of a range of silicones in-situ would mean lubricants, seals, sealants, rubbers, and plastics could be produced locally, without using precious carbon.
    • Transparent Glass - Creating a sense of open space on the Moon will require a very great deal of clear glass. The polar hab designs are alright, but living without sky or being able to look outside is a big sacrifice. The Holy Grail is glass domes over entire craters. Though artificial light will still be needed to get plant life through the long night, in the day plants can bask under real sunlight in a much more natural way under such a dome. People can feel the sun on their skin, and look up to see the real sky (though not a blue sky). Bulk processes to produce it in industrial quantities are needed.
    • Sapphire and Quartz - Both of these crystals have very low thermal expansion coefficients, can withstand high temperatures, are chemically stable, strong, and highly transparent over a wide spectrum. Once alumina and silica - their normal, non-crystal forms - can be refined out of the regolith in quantity, reactors to produce large crystals of them will be set up. On Earth today, large items made of quartz and sapphire are available. Further evolution of that technology enables massive lenses, panes, domes, and tubes of sapphire or quartz. Because constant intense sun is perhaps the Moon's greatest natural resource, such items will be used to do many things that on Earth are accomplished in other ways. Anything that can be done with heat, is probably best done with heat on the Moon. Better to reduce use of chemical processes, as the Moon is almost completely devoid of most common catalysts and reagents.
    Missions Around the Moon

    The LNCs now have much greater liberty to make sorties to anywhere on the Moon, as the ice mines provide plenty of fuel and the skyhooks make fuel requirements very low. The combined complement of almost 300 people on the Moon by the end of this phase provides plenty of skilled operators for these sorties.

    • As mentioned above, surveys uncover deposits of high-grade iron ore embedded in the central peaks of a few craters. They are the remains of the asteroids that impacted there, ones that came in slowly enough, at the right angle, to not have vaporized completely. The most promising case is selected for mining. After study from the surface is completed, aggressive blasting is begun. Unlike the careful, minimal blasting done during excavation in regolith, in this case, small numbers of deep bores are bored, and packed with plenty of explosives, with the aim of advancing into the mountains quickly. The LNCs transport back loads of ore to Inukshuk.
    • A number of large lava tubes are discovered. They are explored in detail. In the one with the large skylight, a small mobile hab is delivered and lowered into it, so a small research team can stay for longer periods and have more tools at their disposal. samples are extracted and returned to Inukshuk for study.
    • A suitable crater with a smooth bowl shape is selected on the Moon's far side, and work begins to convert it to a radio telescope along the lines of Arecibo. It is 3 km across.
    • The volcanic region around Aristarchus Crater is explored.
    • Anchor towers are built on either side of Shackleton Crater, cables are strung between them, and a specially designed exploration rover travels on this cable back and forth, using the slack to get close to the deep dark interior and examine it in detail without touching it.
    • Seismic sensors are set up around the Moon
    • Lalande Crater is surveyed and examined in detail in preparation for construction there. Blasting is done in several areas there, first in exploration, and later to remove materials in key areas while there are still no structures that could be damaged by the flying debris. Thinking now occurs on a different kind of scale.
    The Residence Program Begins

    This program allows any country to send citizens to the Moon for the rest of their lives, for the price of $150 million per astronaut when the program begins. There are 7 rounds to the program, and in each round the price for a permanent spot in the colonies drops by half, and the number of available spots doubles. All those sent must meet stiff criteria set by the ISA:

    • Stable Married Couples - Couples only are sent, and they must be married at least 10 years, have no children under the age of 18, and both at least 40 years of age.
    • Scientists and Engineers - who can play an active role in studying and developing the Moon. Minimum qualification is both people in each couple have at least a bachelor's degree in a science or engineering, and one has a more advanced degree or an outstanding professional career in a relevant area.
    • Good at Shows - They must participate regularly in programming broadcast back to Earth, both by appearing on camera, and by coming up with content for such programming. There are many options - arts, sports, educational content, conversational content, games. Ability in an art or a sport will be part of the criteria by which they are selected.
    • Medical Science - They must donate their bodies to science upon death.
    • Avoiding Pregnancy - they all must have had a vasectomy or a tubal ligation
    • They must be in excellent health
    Broad International Population

    Nations may send a number of representatives, but at the same time, there is a deliberate effort to send a group that truly represents all the races, religions, language groups, regions, and ways of life of humanity.

    The crew of First Hab is expanded to 50 when the RP starts. They are the senior staff, who come from the ISA nations. As the Residence Program is the main initial revenue stream, it is made of people from other nations. There is overlap due to, for instance, the many nations of the European Union wishing to have nationals in the settlement, as only a few would have nationals in First Hab. Other space-faring nations may also forego recuperation of their investment in order to have a few more citizens on the Moon. Still, the bulk of the people in RP Round 1 come from places other than the founder nations.

    Affordable Entry

    Payment for each spot may be made over 5 years. Today, there are 63 countries in the world with annual national budgets over US$30 billion. Examples of countries at that US$30 billion level include Slovakia, Vietnam, Bangladesh, Morocco, and Luxembourg. By the time the program began there would be a number of others. Most of the astronauts would probably be in their mid-40s. They would probably be able to actively participate in colony life for at least 30 years. So, those countries in the list in the point above, for 1% of one year's national budget, would get 2 national superstars on the Moon, that can do way more to inspire national pride and collective interest in science and progress than anything they could do at home, for 30 or 40 years.

    First Round

    The First Round of RP astronauts take up residence in Long Hab once it is finished. They are a very broad cross-section of the human populace. All speak English as a first or second language, almost all speak at least 2 languages. Before going to the Moon, they trained together extensively. This is standard procedure so they learn how systems operate on the Moon and the details of working in that environment, and become a cohesive group able to trust each other and work together closely.

    All residents spend their days mostly in First Hab, running experiments and analyses in labs, building and testing prototypes in workshops, planning missions and the future of the colonies, or operating machinery doing mining, construction, fabrication, or farming. Sometimes they work in the greenhouse or go on sorties. Sometimes they do broadcasts for the people back on Earth.

    The First Rounders arrive over the course of a year in 10 separate groups of 20

    Building the First Homes

    In what will become a core tradition on the Moon, when the First Rounders arrive, the first task they have is to build their own homes. Kitchens, bathrooms, shower facilities, and laundry facilities are shared. Their homes are small affairs that only have to be structurally sound, provide privacy, include a few electrical and comms connections, be no more than a certain height, and take up no more than a certain amount of floor space.

    Other than that they have broad freedom to make their homes however they like. Each group of 20 is assigned to their own shared-facility area. Therefore each group clusters their homes around those facilities, but there is no requirement for them to be within a certain area. They scatter them around nearby in whatever way they decide is pleasing.

    The First Rounders make their homes using the MIPs, robots, and 3d printers. It is not an onerous task. The structures are brought in through the airlocks lacking only a bit of assembly and some detailing. Once each couple has settled on a design, it takes only a few days for their finished home to be set up.

    Before the First Rounders begin to arrive, the ISA staff also move to Long Hab. First Hab is then turned over completely to research. Quarters previously used by ISA crew become accommodations for researchers visiting temporarily. Most of these are people from Crossroads, Gagarin, and the EESS.

    Status by the end of this phase:
    • There are 250 people living on the Moon - 200 First Rounders and 50 ISA staff.
    • By mass, they get about two-thirds of their food from the Greenhouse and the Long Hab gardens.
    • The ice mines produce 100 kilotons of ice per year
    • 100 people live and work on the EESS
    • 50 people staff Crossroads.
    • There have been 200 launches to the EESS carrying a total of 8 kilotons of payload. Almost all of them have carried crew, as well as equipment and supplies for the various stations and Inukshuk.
    • Most of those launches had an upper stage that was refueled with fuel from the Moon, and returned to Earth for reuse.
    • Scaleable manufacturing processes, using purely materials acquired on the Moon or from asteroids, have been developed for the following goods: steel, topsoil, Zylon, a range of silicone polymers, transparent glass, structural glass composites, high explosives, sapphire, quartz, and pure metals including iron, aluminum, silicon, magnesium, titanium, calcium, and manganese.

    The Residence Program - Structure and rules of the 7 rounds

    Although the residents must qualify, and sign a contract stipulating their duties and obligations, they are free to pursue their own projects as time permits. In later rounds residents will have more free time and greater discretion to pursue activities aside from their official duties on the colony.

    RoundSpacesPriceTotal Revenue
    1200$150 million US$30 billion US
    ConditionsOnly couples married >10 yr, over 40, with no kids under 18, min. B.Sc. or B.Eng but higher preferred, one of couple post-doc or experienced pro, arts or sports ability. Note: Qualifications for all rounds are announced several years before they begin, leaving plenty of time for interested people to upgrade skills so they can apply.
    2400$75 million US$30 billion US
    ConditionsSame conditions hold as previous round, greater focus on establishing a truly representative population. The ISA nations add another 50 astronauts, who continue to be the senior staff.
    3800$40 million US$32 billion US
    ConditionsSame conditions as previous rounds, advanced degrees in the humanities now an alternative possible qualification for one member of each couple, other still must be a post-doc or expert pro in the sciences or engineering. The ISA nations add a final 100 astronauts to manage the settlements.
    41600$20 million US$32 billion US
    ConditionsSome single people now accepted, other conditions remain the same. Birth control policies remain the same. The requirement that only nations may sponsor residents is dropped. Many residents now arrive representing foundations, professional associations, religious institutions, and universities.

    Administration is transferred to the Moon Agency and some RP astronauts are promoted into administrative posts.
    53200$10 million US$32 billion US
    ConditionsGreater proportion of singles accepted. Private citizens may now apply, but must qualify, including training, and may not be more than a third of the group. Business interests may provide funding, but may not directly sponsor a resident. Contracts between accepted residents and businesses must be for a fixed time period and be reviewed by the Moon Agency.

    The Moon Agency becomes more mixed between the ISA nations and RP astronauts from other countries.
    66400$5 million US$32 billion US
    ConditionsThe Anshar skyhook orbiting Earth is finished, and because this makes transport so much cheaper, about 2000 of these astronauts are younger married couples around age 30 who have no children but plan to have some. As it is not known how pregnancy and childhood on the Moon will play out, but danger is probable, these couples are advised that should they become pregnant, they must return to Earth for the pregnancy and the first years of the child's life. They may then return to the Moon. The child will be carefully monitored and the family will return to Earth if a threat to the child's health is detected.

    Private citizens may form up to half the group, but must qualify, including training. Qualification in education may now be an advanced degree of any kind, or a successful career in the arts or sports. Private applicants are permitted to have only an undergraduate degree.
    712800$2.5 million US$32 billion US
    ConditionsThe requirement of sterility is eliminated, and the average age of the astronauts drops to near 30. Risks regarding pregnancy and growing children living in space are significant, but have solutions. For the sake of argument, we shall posit the first 6 weeks of pregnancy is not affected by conditions in the lunar colonies, and that children over three can be healthy there, if a careful program is followed that involves extensive centrifuge use, a carefully designed exercise program, and supplements and medication. This is simply an educated guess as to what might be sufficient.

    There is now no limit on how many private citizens may apply, but applicants backed by a recognized group get priority. All applicants must have at least an undergraduate degree. A successful career in the arts or sports is accepted as a substitute in some cases.

    Price for a residential spot when the Moon opens to the public:
    $250,000
    . Population when the opening occurs:
    25,600 souls
    . Total revenue from the Residence Program:
    $220 billion US
    Though the duration of the program could be drawn out by difficult techical hurdles, since energetic investment is being assumed, we shall estimate the whole thing is completed in
    30 years
    .

    Phase 3 - Year 26 to Year 35. Residence Program Rounds 2, 3, and 4

    Fleet Expansion - More Fetching, and the Interplanetary Fleet

    This phase sees the expansion of the lunar fleet to 10 Pod ships (max. payload 250 tons), 14 LNCs (max. payload 250 tons), 10 Hoppers (max. payload 40 tons), and 12 Fetchers (max. payload dimensions 50 m across). All models of ship have been improved, the earlier ones overhauled to the new standards. It also sees the dawn of interplanetary ships.

    Better Fetchers and Hoppers

    The Fetchers and Hoppers are souped up a lot. Now each Fetcher that's on standby (4 of them, 2 at each of the equatorial skyhooks) is attached to a nuclear thermal Hopper on standby. When a target of opportunity comes around, the Hoppers act as a first stage to the Fetchers, accelerating them towards their targets so they reach them much sooner. The kind of acceleration they need to do now justifies them all having nuclear thermal engines. Once the Fetcher is released, the Hopper returns. If necessary, it uses all its fuel on the boost, except what it needs to brake after release and enter an orbit around Earth or the Moon. If that is necessary, a Pod ship or another Hopper is then sent to retrieve it.

    Given the kind of boost the Fetchers get when they are launched, typically they now have to shed speed when they approach their targets. If they were to do that with their low-thrust, high-efficiency engines, it would take a long time and negate a lot the value of the boost they got. So they have frames that can be loaded with tiny solid-fuel boosters during launch prep, however many are needed to do most of the braking on approach. They ignite the number of booster sticks needed to brake sufficiently and use thrusters and their main engines for the rest.

    Both Hoppers and Pod ships are fitted to have modular fuel tanks that can be switched out easily for ones of a different size. Hoppers that are on Fetcher duty are fitted with much larger fuel tanks so they can thrust long enough to speed the Fetchers up enough to reach their targets in a timely manner. Pod ships hauling the returned asteroids down to berth with a skyhook also need to be able to do much longer burns that use far more fuel than normal, which means they need larger tanks for that. In fact, towards the end of this phase, as asteroid mining gets rolling, a nuclear Pod ship is made just for that job.

    Other than that, the Fetchers are larger, and are set up for modular last-minute assembly with the appropriate set of pieces, depending on the nature of the target. Characterization of the asteroids spotted has improved. If they are judged sufficiently solid and rigid, the complex SHEPHERD bagging mechanism isn't used. Instead the asteroid is just wrapped in a net for hauling, which is much lighter. It is also possible to vary the number of engines and size the fuel tank to the target.

    The net result of all this activity is examined under the Gagarin Station - Asteroid Mining Arrives section.

    Interplanetary ships

    Three ships are built that will make many journeys around the solar system:

    • The Li Bai - is a ship designed to move quickly between the Earth, Venus, and Mars with a payload of up to 3.5 kilotons. It uses huge solar panel wings to power a large cluster of VASIMR or Neumann engines. For trips with crew, it has a pod section with inner measurements of 20 m long by 6 m in diameter, surrounded by radiation shielding that is 1.5 m of liquid ammonia, between the inner and outer hulls of carbon fiber and fused quartz. That pod masses 1.2 kilotons, leaving 2.3 kilotons for cargo. For purely cargo runs, the crew pod is replaced by one designed to carry and deploy a wide variety of robots and probes. It has a large, high power transmitter dish and several kinds of multi-use telescopes built into its nose section. As with all ships in these times, it pilots itself.
    • The Rumi - is a modular heavy lift ship for the inner solar system, that can move 10 kilotons to Mars or Venus when fitted with only the minimal hydrolox engines needed for orbital maneuvers. In that configuration it is the forerunner of the Toss ships - it uses the speed it gets on release from the skyhooks and the boost from a Hopper as first stage to get around, not its own engines. On its first trip, to Phobos, it runs this way, aerobraking to enter orbit around Mars. But it has many possible configurations. It has a modular setup similar to the Hoppers, so that it can be outfitted with the solar panels, engines, and tanks that fit its current job. With small loads it's capable of reaching the asteroid belt. It has a heavier frame with heavier robotic arms that move on rails. The arms have a range of attachments for assembly and construction activities.
    • The Roddenberry - is a ship for the outer planets, and Mercury, whose VASIMR engines run on power from three nuclear reactors. The reactors are also configured to power nuclear thermal engines. It's a beast of a ship, made for great speed and power even with pretty hefty payloads. Don't worry about favorable trajectories, if you need to get there, the Roddenberry will get you there, any time. It'll take a kiloton from Earth to Callisto in 2 months. It also has the frame and equipment for construction activities. It's the can-do ship. Extinction-event-level asteroid going to hit the Earth in 2 years? You want the Roddenberry. Has an explosion on board the Rumi sent it careening off course with 100 souls aboard? Call the Roddenberry. For reasons that should be apparent to most readers, that's why the Roddenberry is named the Roddenberry.
      Also in this spirit, most of the time the Roddenberry is exploring, going where we've never been before. It is equipped to scavenge fuel - it can land on and take off from any airless body in the solar system, its robots can dig and haul, and it has gear to split water into hydrogen and oxygen and liquify it. Its nuclear engines will run on just about anything.
    Final 2 Skyhooks

    One more polar skyhook is built, and named Babel. A second equatorial skyhook is erected and named Magnificent Desolation, or more commonly, Maggie. The second skyhook on the equator is always on the opposite side of the Moon from Gagarin. The orbital period of all the skyhooks is the same. If they were all in one plane, each of the three polar skyhooks would be 120° from the other two. This keeps all the skyhooks as far apart from each other as possible. It also means that during the night, the new colony at Cernan's Promise has a line of sight to the anchor station on at least one skyhook most of the time. This way power from the solar arrays on those stations can be beamed to the colony's microwave receiver most of the time.

    The existence of three polar skyhooks means one of them passes within 3° east or west of any spot on the Moon once every 5 days. A LNC that wasn't heavily loaded could manage the extra distance and the turn necessary to meet up with the closest foot platform on any pass. So, most of the time, a LNC with a regular payload can go to or from anywhere, if needed, with a delay of no more than 14 hours (the time it takes a skyhook to orbit once). (A LNC that is near empty can also go point to point anywhere at any time, in the event of an emergency.)

    There are two equatorial skyhooks because they are the connection to Earth - and the rest of the solar system. It is much easier for ships from other worlds to rendezvous with a skyhook in an equatorial orbit, as the Moon's equator is aligned very closely to the plane of the ecliptic (the plane on which the planets lie). Equally, any direction of travel on that plane is available once per orbit.

    Because asteroid retrieval remains a matter of reaching the very small Near Earth Asteroids, which are far more numerous than larger ones, having launch windows for pursuit of new targets open twice as often is a big help. As traffic to various points in the solar systems grows, the flexibility and added capacity of two equatorial skyhooks will become increasingly useful.

    Each of the new skyhooks is given a 10 kiloton asteroid as an anchor mass. As these asteroids are mined, material removed is replaced by material sent up from the surface, to preserve that mass. They are set up with solar panel arrays, power equipment, and microwave transmitters so they can beam power to the colonies. They don't get space stations. The mining done on them is almost completely automated, and what isn't, is done by tele-operation. In the rare event that people have a reason to be on the anchor, a crew pod can be placed on the climber car and sent up, or a ship can dock with it.

    Gagarin Shipyard

    The shipyard goes into full swing. In addition to the materials Cernan's Promise produces for it, machinery and robots to turn ore from asteroids into usable materials, and fabricate things on-site, is created, and multiplies over this phase. Most of that infrastructure comes from the factories at CP. Components and modules for spacecraft and space stations are also sent up the tether, and at the shipyard are assembled. Many of the arriving structures are incorporated into Gagarin itself, filling out and extending the superstructure according to the long-term plan it was designed for. More about that, and manufacturing there, in the Gagarin Station section.

    Once fully operational, all interplanetary missions launch from Gagarin's skyhook, after their craft have been assembled there. The Rumi, the Li Bai, and the Roddenberry are built in its yards. It is the existence of Gagarin and Cernan's Promise that allows those ships to be so big and powerful. Most satellites of Earth launch from Gagarin as well. Of the ones that don't, most launch from the EESS after final assembly there, which usually includes the addition of parts from the Moon (such as solar panels or Neumann Drives). Some manufacturing processes that require micro-gravity occur at Gagarin as well.

    Crews for deep space missions usually do final training at Gagarin. It's also common for at least part of the crew to be drawn from the crews of Gagarin and Crossroads.

    Interplanetary Launches from Gagarin

    The ships, fuel, and tether launch facilities of Gagarin allow the launch of a number of deep space missions with a scale and scope never previously possible. Thanks to Zylon produced on the Moon, Gagarin's tether cables have been massively upgraded. The upper tether is now able to dock ships massing 10 kilotons. The tether has already been used to sling probes on trajectories to Venus and Mars with such speed that no fuel is needed to arrive. At those destinations, aerobraking is used to enter orbit. That means ships can go to either world using only maneuvering thrusters. Their massive 10 kiloton bulk would be almost entirely payload.

    Or, with high specific impulse engines like VASIMR, a small fraction of the payload could be sacrificed for the sake of really short trip times. For more distant destinations, engines and fuel are needed. To get to Callisto, Jupiter's outer moon, with VASIMR drives about 1/6th of the ship would be fuel. Increase that to a third or a half, and that trip can be shortened from around 3 years to less than a year.

    In most cases the spacecraft sent are only a tiny fraction of 10 kilotons. The reason the tether has been beefed up to take something so massive is for the missions to Phobos.

    Phobos and Mars

    Phobos is a small moon orbiting about 6000 km above the equator of Mars. It's a dusty potato-shaped thing, with a giant crater at one end. Three missions are sent there. The first is a research, scouting, and prepping mission, the second is the undertaking of building a skyhook around it, essentially turning Phobos into its anchor mass, the third brings people who tele-operate the robots landed on the Martian surface, exploring and experimenting.

    Mission One - Research and Prep

    This is the Liu's maiden voyage. It gets the Mars system ready for intense activity. On Phobos, a set of spider-legged walking rovers and a small swarm of orbiters are deployed to examine the whole surface. It is widely sampled, scanned with ground-penetrating radar, and its inner structure mapped with seismic imaging. A large and complete lab does batteries of tests and detailed analysis. Several holes are bored 200 m deep and probed for water ice. A transmitter is set up that can send high volumes of data back to Earth. Engineering tests are done for planning of the next mission. Prototype equipment is tested.

    It also deploys a set of GPS satellites for surface navigation on Mars, and a set of superb observation satellites that image the surface in high detail in lots of wavelengths, and scan with radar and lidar. Deimos is also examined, by the Liu itself. After a bunch of samples have been collected from both moons and all the equipment is working, the Liu returns to the Moon.

    Mission Two - Space Elevator and Initial Mars Operations

    This was inspired by the post about just such an elevator in 2016, on Hop's Blog

    • The Rumi pulls into the Lagrange point between Phobos and Mars, on its maiden voyage. It is fully loaded with 10 kilotons of payload. It keeps station at the point, just 3 km above the surface of Phobos, where the pull of the gravities of Phobos and Mars balance.
    • To securely anchor the space elevator, a belt made of a set of cables is wrapped around the waist of Phobos. A tether is extended from each side of it, one down towards Mars, and one up into deep space. The Rumi assembles the structures of a space station on the Marsward tether, at the LaGrange point. Later arriving ships will dock there securely, well away from the unstable surface of Phobos.
    • The Marsward tether is extended 5100 km, to 800 km above the Martian surface. It can bear a ship massing 100 tons. Dropped from this altitude, a LNC only has to shed about half the kinetic energy it would have to shed from low orbit to make a soft landing.
    • The upper tether, on the opposite side of Phobos, is extended 4500 km. It can bear the great mass of the crew ship that comes next. Released from the top platform, a ship has about 3/4 the energy needed to reach Earth. Together the system functions like a skyhook for Mars, that just happens to have a small moon as its anchor mass.
    • The belt and the two tethers make up 8 kilotons of the payload. 500 tons is fuel for the coming crew ship, for their return home. The remaining kiloton or so of payload is a nuclear power plant, the infrastructure for beaming power along the elevators, all the equipment, supplies, and infrastructure of the station, and a small LNC that is dropped from the tether foot and descends to the surface of Mars. (More on the Mars LNCs in the next section.)
    • The LNC's robots and rovers set up a nuclear reactor, processing plants for extracting argon, nitrogen, and oxygen from the atmosphere[?], and storage tanks for the extracted gases. Then they go exploring.
    There is no evidence of subsurface water at the equator of Mars, where the LNC would be dropped. If there was, there could be a prototype plant producing methane, from the water and the carbon dioxide that makes up most of the atmosphere. This process was first proposed for fuel production on Mars by Bob Zubrin as part of Mars Direct.
    Mission Three - Crew of 12

    The crew gets to Phobos in less than 2 months, aboard the Liu.

    At Phobos, except for a few EVAs, the crew works from inside the Liu. Phobos appears to be deeply covered in fine dust. It has a very weak gravity field. The rovers were designed to deal with that, humans on the surface could quickly be enveloped in a cloud of dust in which they flounder blind. It is better for most operations to be conducted remotely.

    The Liu delivers 2 full-sized LNCs specialized for Mars. Their nuclear thermal engines are designed to run on nitrogen or argon. They are equipped to do entry, descent, and landing by retro-propulsion.

    And it carries a kiloton of equipment and supplies which the LNCs ferry down to the surface. To do so they return several times, after refueling from the tanks of liquid nitrogen and liquid argon on the surface.

    The robots delivered are remotely operated by the crew from Phobos station, but are capable of doing many tasks without supervision. They set up a field of solar panels and also a microwave rectenna grid that receives power from new solar panel masts on Phobos. They set up a hangar and a lab.

    Then they set out to explore Mars in deep detail, searching specifically for life, or signs of past life. Unless and until that search leads to firm conclusions about how humans might affect or be affected by any possible life on Mars, humans do not set foot on the planet.

    Cloud-tops of Venus

    A series of probes and test vehicles are sent to the atmosphere of Venus. They are designed to stay aloft by inflating with nitrogen gas once they are released from the delivery vessel, about 50 km from the ground. Once a good design is found, several larger versions are sent.

    Settling Venus by creating floating cities has been studied recently at NASA. These missions explore Venus from above while developing the technology needed to create a structure that could stay aloft indefinitely, doing repair and maintenance without outside assistance.

    Sailing to Mercury

    Solar sails become ever more effective the closer they get to the sun. Mercury, as the planet closest to the sun's gigantic gravity well, requires as much delta V to reach as distant Uranus. So, it is a good target for missions that develop solar sail technology.

    Launching a solar sail vessel from a skyhook tip platform allows sails of truly vast size to be unfurled prior to release of the vessel. This is the key to making them an effective way of moving things around the solar system. Development of membranes that are sufficiently light, strong, and durable is spurred by sending a series of probes to Mercury propelled by light sails.

    Ceres

    Ceres is a wonderful place to get stuff for the Moon. It's a really interesting place in its own right too. But it's hard not to drool over it as a resource if you live on the Moon. All evidence points to it being composed largely of water ice, mixed with a variety of clays and salts full of key things the Moon lacks - carbon, nitrogen, chlorine.

    Farther from the sun there are lots of big snowball moons made mostly of water ice, because out there it is stable even in direct sunlight. Ceres is the place closest to us that is like that - a mantle of muddy ice wrapped around a rocky core - but only because a layer of dust has protected the ice from the heat of the sun. It is half the distance away as the moons of Jupiter and has a fraction of their surface gravity. It is just begging to be mined (as the show The Expanse has noted).

    Mining of the Moon's poles continues to go well, but there is a long range future to consider here. The water ice in the Moon's permanently shaded craters may well amount to no more than the water found in one large lake on Earth. The Moon is going to want more than that. When the first mission launches, It takes about as much water to fuel the VASIMR engines of a ship to Ceres and back, as water it could haul for that amount of fuel there and back (its engines run on hydrogen extracted from water). But, carbon nanotube cables will soon come into play. When they do, Ceres will already have been thoroughly explored, and the engineering of mining it already worked out.

    This is the Roddenberry's first stop on its maiden mission. It carries a mini space elevator with which it will attach to the surface from a position in synchronous orbit around it, at an altitude of 706 km. It feeds out the tether for this, and also an upper tether about the same length, keeping the center of gravity of the system balanced at that synchronous altitude. The Ceres LNC, already sent down, delivers equipment that anchors that tether to the ground. The climber car is sent down and loaded, and starts ferrying up the material that will form the anchor mass once the Roddenberry leaves. In all, the tether and its infrastructure mass only about 200 tons - a modest tether building project by this time. Together with the LNC, equipment, and supplies for surface operations, the payload for Ceres is about 400 tons.

    During initial construction of the space elevator, the Roddenberry's reactors provide power. Once it is anchored, a large solar panel array is attached to the upper tether. As the light at that distance is weak, the array has to be very large to provide sufficient power. Because gravity is so low, that power can simply be passed to the surface, and to the climber car, through wires connected to the space elevator cables. There is no need to save mass by transmitting power as microwaves. The reactor of the LNC also provides power when it isn't flying, which is most of the time. The LNC was designed as much to perform this duty, as to do transport. When its departure date for Jupiter arrives, the Roddenberry breaks orbit and heads for Callisto.

    Callisto

    Callisto orbits just outside Jupiter's powerful radiation belts, but inside its magnetosphere. That makes it the most attractive destination in the Jovian system. The radiation belts soak the surfaces of the other main Jovian moons in ionizing radiation. By contrast, the protection Callisto gets from Jupiter's magnetosphere makes it one of the solar system's most sheltered places from radiation. Its surface is a mixture of ice and rock. Patches of pure water ice exist on the very surface of Callisto. It also has hydrated silicates and ices of carbon dioxide and sulfur dioxide. Best of all, it is the size of the planet Mercury - truly a world.

    Callisto will be the base for exploration of the whole Jovian system. To do that, its water ice needs to be mined and processed into fuel for the Callisto LNC and the observation satellites sent to the Galilean moons and to orbit Jupiter. The Roddenberry pulls into orbit around Callisto, and once a suitable patch of water ice has been found near a pole[?], it sends down the LNC that will set up the equipment to melt it, purify it, process it into hydrogen and oxygen, and store it. A nuclear reactor is set up to power the equipment. In this case, that reactor is incorporated into a rover. When enough fuel is stored, it disconnects from the fuel production station and goes exploring.

    Like the Moon, Callisto's axis is inclined very little to the plane of the ecliptic. Thus, like the Moon, there may be places near the poles that have sunlight most of the time, and others that are in permanent shadow. The permanent shadow would be cold traps for volatiles that have evaporated away elsewhere. In the spots that are lit most of the time, equipment would have a milder thermal environment to cope with.

    Callisto's LNC has powerful engines and large tanks. It can reach any of the Galilean moons, land, and return to Callisto. Its nuclear reactor provides lots of power when it isn't flying. It and the Roddenbery deploy the satellites for Ganymede, Europa, and Io once fuel provision has been looked after. A separate constellation of satellites is put into orbits around Jupiter itself. These satellites have heavy shielding sufficient to protect the satellites' systems from Jupiter's radiation. As needed, the LNC will refuel and service those satellites so they continue observing and transmitting for a long time. The LNC can also ferry the nuclear rover to the other moons to conduct surface exploration.

    That done, the two ships return to Callisto. The LNC and the Roddenberry land, together fill Rod's tanks, and then Rod returns to Earth.

    2nd Earth-orbiting Space Station

    Using modules, tanks, solar panels, trusses, motors, pumps, radiators, and engines made on the Moon almost entirely from lunar and asteroid materials, another space station is placed in an equatorial orbit around Earth. The robots and ships that assemble the pieces are also made almost entirely on the Moon from lunar materials.

    This station is two cylinders on opposite sides of a spherical central hub. Around the hub is a box of trusses with open sides, large enough to extend over the near ends of the cylinders. The solar panel wings extend from either side of the box. Each cylinder spins fast enough to create a centrifugal force equal to a full Earth gravity on their outer walls. One spins clockwise, the other counterclockwise, and the hub remains stationary.

    At first the cylinders are wider in diameter than they are long. They are designed to be extended over time. They measure 200 m across and 100 m high each. When the station opens, they are almost entirely empty. They are filled in as businesses, facilities, and residences are created by people who invest in the station.

    Robotics and AI

    This is the point where the sophistication of artificial intelligence allows robots to perform many tasks without any human oversight. They can be taught to do almost any task done by people in industrial jobs today, as long as it is fairly repetitive and predictable. Once they have learned, they alert a human only when some unforeseen event prevents them from continuing. They are capable of working in teams, coordinating what they do with other robots.

    This capability is what allows the interplanetary missions to be done on such large scales. In almost all cases, the missions are executed by artificial intelligences and robots. They don't wait for further instructions from people on Earth or the Moon every time they finish some simple movement, like rovers today. They complete entire projects almost on their own. They have blueprints in their memory for a long series of points in the construction of the space elevators on Phobos and Ceres, for instance. They figure out how to reach each point in that series, so the construction matches the blueprint, using the library of routines they have. The space elevators and other such things have been designed for easy deployment on site, same as equipment to be installed on the ISS is today, but this still requires very complex behavior and problem solving.

    This capacity speeds up development in space dramatically. It's why so many things get done during this phase, and later phases are exponentially more active again. Factories are built that manufacture entire vehicles and robots almost by themselves, staffed with robotic machinery. The raw materials that are used in those factories arrive from other factories that are almost as automated. As long as the robots operate in a predictable environment, they can do almost anything. By the end of Phase 3 many items and pieces of equipment are made completely of lunar materials, by lunar machines. Only very sophisticated and delicate machines come from Earth, such as computers and view screens.

    Cernan's Promise

    The colony built on the eastern rim of Lalande Crater will house 1600 people by the end of this phase. Plans for a town for 50,000 people, surrounded by the factories that form the core of lunar industry, have been carefully drawn up and are methodically executed even as industry ramps up. The residents participate in construction of the factories and the town, but mostly that is handled by robots on their own. People focus on research, design, and planning of industries for Cernan's Promise. As soon as possible, the first factories at CP begin building modules and equipment for spacecraft, space stations, robots, satellites, and tether facilities.

    Construction of Initial Habs, Factories, Hangars, and Mines
    • A remotely operated set of equipment excavates a pit and builds the first habitat inside it. That habitat is an atrium design with a radiation blind roof. A team of 20 people moves into that hab and oversees continuing construction.
    • The surface near the habitat is paved, including the landing pad for the LNCs, connected by a road to the hab area.
    • A microwave rectenna is built to provide power to the new colony. It receives microwaves beamed from the skyhooks. A set of flywheels are built for short-term power storage when no skyhooks are beaming power, and for added power during heavy loads. Further flywheels are added as needed. The rectenna is sized to receive far more power than it does for the first while. Over time the energy in the beam is increased.
    • An airless hangar is built that houses a repair and maintenance station, a set of dust roasters producing pure metals, and a series of machines that turn that into components: 3d printers, casting equipment, welders. The hangar has a lot of extra space where machinery can be stored at night, and large pieces can be produced by combining structures made in the MIPs and the metal-working machines.
    • On the open surface, a series of MIP stations, solar furnaces, and chemical reactors are built. Some of the reactors are multi-stage processes in their own sheds. More of all of these are built throughout this phase, to support the factories and hangars with a range of supplies, and support continuing construction.
    • A factory with a thin atmosphere is built and filled with glass fiber equipment. Unlike hangars, factories have internal divisions, including multiple floors, columns, and internal walls. This factory produces short fibers and thread made of different kinds of glass, and from that, fabric, cable, nets, batting, and bulk fibers for composite materials. Some of that is made of simple basalt, some is aluminosilicate glass, or has other glass formulas. Composite materials in simple shapes are made with molds, presses, or rollers: pipes, rods, panels, containers, rings.
    • The excavation for the galleries and the atriums is all done. Some sections were blasted out during earlier exploration missions.
    • Previously identified ore deposits start to be mined. There is a spot in the central peak, and another far down the south wall, that are particularly high in KREEP elements. These deposits are tunnelled into by blasting.
    • A STeP is built for bulk processing of regolith to purify a range of chemicals, produce bulk molten regolith, and provide extra power.
    • The upper gallery and the north atrium hab are built.
    • A multi-storey airless factory is built. On the ground floor is bulk production of transparent glass, in panes of varying thickness, profile, and shape. It also produces Fresnel, convex, and concave lenses.
    • The 2nd floor takes glass panes from the ground floor and prints photovoltaics and circuitry onto them. Its output of solar cells is assembled into panels and shipped to Inukshuk and the skyhooks.
    • The 3rd floor is set up for production of Zylon. It contains a number of reactors that turn the carbon chemicals from asteroids and Ceres into precursor chemicals for Zylon. Once the complex polymer that constitutes Zylon is made, it is carefully spun into high-quality fibers and threads. These are then made into cables, that are woven into components for the skyhooks.
    • That floor also houses specialized reactor chambers for making silicone polymers.
    • The 4th floor has reactors producing panes, tubes, lenses, prisms, and domes of pure quartz and sapphire. It also has facilities for drawing molten silica into optical fibers.
    • A silo is set up for bulk production of topsoil.
    • A small factory structure is built in a pit and a production line for explosives set up in it.
    • The lower gallery is built, the tube habs are added to both galleries.
    • The south atrium is built, and Teacup crater is covered with glazing and sealed.
    • A 2nd, larger STeP is built.
    • A big hangar is built for more advanced assembly of components, producing entire robots and vehicles, and a range of machinery.
    • Larger factories producing all of the products listed above are built clustered around that hangar, making larger quantities, with more variety and better quality.
    • The long dome hab near the crater floor is built.
    Greenhouses at Inukshuk

    The earlier greenhouse design is extended to versions that have three domes clustered around a rotating central mirror that reflects light in such that every 24 hours each gets 8 hours of full light, 8 hours of a dim twilight, and 8 hours of darkness. Six such tri-part greenhouses are built clustered around a central tower that provides a mirror for each that concentrates enough light on their distributing mirrors for optimum growth. That tower is a kilometer tall and is fitted with six mirrors 120 m in diameter, each on an arm that positions it above its corresponding greenhouse cluster. The arms spiral around the central support tower so that no mirror even blocks another. The only shadow that falls on the mirrors is the narrow one from the tower itself. Over the day, each mirror rotates to follow the sun. Each of the three domes in the tri-part clusters is 180 m across. In the center, these domes are 30 m higher than at the rim, and the ground within is a bowl shape 20 m lower in the center than at the rim.

    Five of the greenhouse clusters are interconnected, and there are work rooms in the spaces between them. The last one is isolated from the others by an airlock. This one is an extension of the earlier project to create a stable ecosystem that needs no external input to continue growing. The whole set of greenhouses is about 3 kilometers away from the other buildings and has to be accessed by rovers with pressurized cabs, or in space suits. The airlock for the whole complex will fit the largest rover. On the other side of it is a pressurized garage that will fit several such vehicles.

    Although food production (and medicinal plants) continues to be the top priority of the greenhouses, each set of three is tweaked to have a different climate that favors different ecosystems. A small set of animals is present in each, mostly insects, but also some fish, some reptiles, a few birds, and a few small mammals. The animals all roam free, though their populations must be carefully controlled. An effort is made to create populations that balance each other as much as possible to minimize the need for interference and mutually reinforce the health of all the species present.

    Gagarin Station - O'Neill cylinders and the Shipyard

    For this phase, the north and south halves of Gagarin Station are specialized for two separate activities. The north half is the shipyard, part of which is microgravity manufacturing facilities. The south half is the first O'Neill cylinder, providing a large, full gravity habitat. The core of the station is the tuning-fork shape that bends around the Zylon-reinforced stone shaft that joins the upper and lower tethers, where the climbers dock. That piece is aligned along the east-west axis, with the tether running between the two posts of the fork, going up and down.

    Attached to the north side of the fork is a double sphere, one nested inside the other. The inner sphere contains a thin atmosphere of argon, for manufacturing processes that benefit from a gas medium, either for removing heat or providing some pressure. The outer sphere is covered to provide a space with a controlled temperature (out of sunlight), reduced radiation, and where loose items remain contained. The inner sphere is 200 m across, and the outer sphere is 300 m across.

    The sphere has a ring of trusses around it that extend north, forming a long cylinder mostly open on the sides. Above and below it are great solar cell wings, docks extend from it east and west from its mid-line. The far north end of the cylinder is open. That is the mouth of the construction bay, which is the whole space within that tube, down to where the sphere begins. It can fit an object up to 300 m across and 800 m long. Or, that is the largest structure that can be built inside it.

    The south post of the central fork is quite a bit fatter than the north one. The whole fork is pressurized. As well as being the structural support that integrates the shipyard and the O'Neill cylinder with the skyhook, it is where all the airlocks are. The south post has an airlock on the bottom 5 m across, it is where passenger pods are normally mated so people can enter the fork and from there enter the cylindrical hab. The end of that post has a much larger airlock 20 m across, which is where the largest cargo pods are mated, to bring in large objects or unload a high volume of goods. There is a big, sturdy ring joint near the base of that post, aligned with the tether. It is about 30 m in diameter and 30 m long. The whole cylinder south of that spins around that joint, completing one turn about every 30 seconds.

    South of that ring the shallow north dome of the O'Neill cylinder stretches away, to a total span of 250 m. It is 350 m long and has another shallow dome capping its south end. The south dome is glazed across the middle 180 m of the span. The panes are hexagons 8 m across made of 6 laminated sheets that together are 15 cm thick. The middle 40 m is the span that forms a giant Fresnel lens. It is there that the mirror outside the south end passes sunlight into the cylinder, which the Fresnel lens spreads out so it falls evenly over the inner cylinder walls.

    The landscape surface of the cylinder, the one that faces the 'sky' - being the open space in the core of the cylinder - gets slowly covered with soil to a depth of one meter. A shell structure is placed around the north end of the cylinder, its sides, and the unglazed outer portion of the south end. That shell doesn't rotate, it is fixed to the fork. It is built up over time to a thickness of 3.5 m of gravel, rock, and regolith. The south cap of the shell is closed in with glass cells filled with water, forming a barrier 3 m thick. All this work extends a few years into the next phase, as 3.1 megatons of rock is involved. The mass for the shell mostly comes from asteroids, the water for the end cap mostly comes from the Moon and Ceres. Once it is complete, the radiation within the hab is low enough for life-long habitation.

    Provided they have that level of radiation shielding, O'Neill cylinder habitats may be critical to space settlement. It depends on how well people can adapt to a low gravity environment. It may be necessary for long-term health that people either live in, or spend a large proportion of their time in, a full gravity or something close to it. If that is the case, it may not be possible to have a full life living on the Moon, and true human communities would have to exist in orbit, in these cylinders, which are spun so that centrifugal force imitates Earth gravity on their inner walls.[?]Later in the timeline, these cylinders will be the homes of pregnant couples and children under three.

    We know people can remain healthy for at least a year in microgravity if they follow a careful exercise routine. At this point it is sheer speculation how well people would adapt to living permanently in low gravity, if they maintain all of the health routines that the colonies have been designed to support. It is reasonable to have confidence we can live for years in good health in such conditions, but we can't say if health problems would crop up after some number of years and possibly be serious. Lacking data, this project supposes that there will be no problems that can't be handled without much trouble. The area where skepticism about this is highly warranted is pregnancy and childhood, as noted.
    Gagarin Station - Asteroid Mining Arrives

    The time needed to return an asteroid to a skyhook is greatly reduced by the team effort of the Fetchers, Hoppers, and the nuclear Pod ship. Small targets under 3 kilotons are very commonly available and quick to retrieve, so they still make up the bulk of targets. In most cases, they can be returned and docked at a skyhook in 6 to 20 weeks. Large targets are retrieved twice, in one case a carbonaceous asteroid massing 50 kilotons, and in one case a metal asteroid massing 60 kilotons. In all, 100 asteroids are returned for mining, with a total mass of 250 kilotons.

    Units to process ore by heating or melting it, and reacting it, are sent up from Cernan's Promise. The rocky material in the asteroids, which is similar to lunar regolith, is generally considered worthless except as radiation shielding. If it is high enough in silica or alumina, that may be refined out for glass, quartz, or sapphire production on site. Other stone is simply added to the exterior of the cylinder hab of Gagarin unless it has a high enough content of hydrated minerals or valuable metals to be worth processing. Carbonaceous asteroids are processed for carbon, water, and volatiles. Metal asteroids, and other asteroids with metal bits, are processed for iron, nickel, cobalt, platinum group metals, and semiconductors. The iron is mostly stockpiled - there's just too much of it, as it has been replaced in most applications by other options that are lighter, stronger, or both.

    By the end of this phase, there is enough experience, and the spotting telescopes have advanced enough, to pick out the very best targets - with a high content of metals, carbon, or water. The Fetchers only go out after those. If an odd or rare asteroid is spotted, and it is small enough, it is retrieved for study, at Sagan Station.

    Power From Space

    As mentioned above, the first factory built at Cernan's Promise in part produces solar cells, and more such factories are built at an accelerating rate once the infrastructure for that starts accumulating. From the beginning, part of that output goes to solar power arrays being built in Earth orbit. The cells are sent up to Gagarin, where they are assembled and placed on trusses, and connected to very large microwave transmitters. Thrusters, reaction control, radio dishes, control units, wiring, radiators, and any other needed kit is installed on the trusses. Finally, the Pod ships take the units to their geostationary orbits, assembles them, and deploys them.

    These units then beam power to Earth. Receiving stations on Earth convert the microwaves to electricity. It's the same technology as the power beamed from the skyhooks to the colonies. For it to work for Earth, the nations receiving the power need to arrange for the right microwave spectrum to be available - 5.8 GHz - and for the beams to not cause interference with any other microwave spectrum use around the ground receivers.

    Ground receivers have to be quite large in order to receive the power as a beam weak enough for it not to affect weather or plant and animal life. The receivers are essentially grids of wires, a mesh that is mostly open to the sky, so they can be placed almost anywhere without interfering with anything below. The likeliest option is over farmland. There needs to be many such receivers to get enough power to provide a large fraction of a nation's electricity.

    Lunar Life
    A New and Unique Culture

    The residents begin to form a culture of their own. Their environment has caused them to quickly develop unique customs - in sports, crafts, cuisine, fashion, dance, hobbies. A few examples:

    • The two weeks of night at Cernan's Promise stimulated the development of customs to adapt to that, as it feels so unnatural. At Full Earth, which is lunar midnight, when the Earth is fully lit, they tended to gather to gaze at it, and quickly realized it was a good time to tell stories. After that Full Earth became a time to do that, complete with snacks and drinks customary to the event. They set up a campfire to gather around for that (a small one burning pure alcohol, as smoke is a serious nuisance and there is little appropriate fuel).
    • It is easy to move quickly on the Moon, the problem is stopping, and turning. Gravity is much lower, but inertia remains the same, making these maneuvers complex. People take to making and carrying specialized canes that help with this, so they can easily move fast in a controlled manner. The canes end up being useful for doing fancy lunar parkour maneuvers as well, which have become very common. People take to making very fancy, personalized and customized canes.
    • Insects continue to be an invaluable source of protein and fat, but people also continue to be rather resistant to eating them. They taste good, but the tastiest ones also tend to be the ones that are hardest to accept - grubs, pupae, caterpillars. People develop recipes for grinding them up and making sausages and patties that feel a lot more acceptable, or toasting them dry and making a sort of flour that then is used to make fillings for savory pastries, or as an ingredient in loaves and cakes.
    • Architectural design is highly important to the residents, as their lives are spent almost entirely in a pretty restricted space missing many aspects of Earthly nature. They have strong opinions about it. People often spend their spare time in group activities that detail, enhance, or renovate all sorts of structures - gardens, walkways, fountains, lamp posts and lighting fixtures, their shared kitchens and eating areas, their shared baths, public art. This is greatly helped by the ease of having complex items fabricated, and their intimate familiarity with those techniques. But, they often prefer to carve, weave, paint, or sculpt things by hand. Just because.
    • They become quite fearless of heights. They develop a strong tendency to place things high up walls or in very tall shelves - including their homes. If they need to reach something high, they stand on someone's shoulders. Or on the shoulders of someone who is standing on someone else's shoulders, who may even be standing on the shoulders of a fourth person. They really like their open spaces, spaces that feel large enough to be a little like being outside, so they maximize open space as much as they can, with this stacking approach.
    • They start to enjoy a casual passtime of water-tossing. This is the act of tossing a mug or a bucket of some fluid, usually water, between people who may be several meters apart. The low gravity gives people time to line up a recipient to properly catch the liquid, and allows that liquid to remain more cohesive, instead of splitting into droplets. There is of course an art to it, which keeps it interesting.
    Robotic Society

    The Moon has become the place with the highest density of robots anywhere, and they are used for everything. Many chosen residents are specialists in robotics. Their work on improving them leads to advances that are also used on Earth. The Moon population becomes very adept at creating systems for robots to do things efficiently, quickly, and well. The populace develops the habits that used to be the domain only of people who had personal staffs, meaning the very wealthy. Many robots are so sophisticated they are treated not very differently than servants. They are given verbal instructions and respond verbally, they modify their behavior in real time and usually adapt it to an unforeseen event or factor without needing to consult anyone. They can even work in teams. This impacts the psychology of the residents deeply. In broad terms, their behavior aligns most closely to the aristocracy in Europe at the peak of the Industrial Revolution - they restrict themselves to intellectual pursuits, have exacting standards, and are used to ordering people around - even though now they are ordering robots, not actual people.

    The Beginning of Tribe Society

    Residents continue to train together in groups of 20 or 30 people before they go to the Moon, and to continue to organize themselves around shared kitchens, baths, and laundry facilities. About half-way through this period, this stops being because there is any need to do this. It's because they prefer to do this. Robots do the drudgery anyhow - they clean up after cooking and eating, wash the clothes, fold them, and put them away, sweep the floor, all that sort of thing. So, it is rather nice for people to gather, cook together, and eat together, just as a social activity. Since there are no children, people feel a broader need for contact like this.

    People now mostly put a small kitchen and bathroom in their homes. The toilets work without water, so the waste is easily collected for processing for the gardens or for topsoil production. The robots do that, no biggie. The robots also usually are the ones who refill the water tank for the shower and sink, every day or two. And they switch out the ice packs in the ice-boxes, and clean the microwave and the grill, or what have you. Some people like to do that themselves. Or they just go to the shared baths and eat always in the shared kitchens, just a quick sandwich if need be.

    The baths are more for long soaks or a good sweat, with friends or on your own. There you can bathe in style. They have become adept at creating giant thermoses, basically - molded shapes with a vacuum in their core. Great for tubs or saunas that hold their heat. And hot water is no problem at all, use as much as you want. Cold water too, same thing. Baths and saunas take on the role they have in traditional Japan or Sweden. They remain held in common, so they can be grand and fancy, and people can enjoy sharing the experience.

    The sense of shared identity in these small groups becomes so strong, colonists simply refer to them as tribes. Usually each tribe is composed of the people who trained together before they came to the Moon, but sometimes people switch tribes. (If they do, usually they move their house with them. Not just the contents, the actual house.) Tribe members have a very high level of ongoing contact with each other, and make many decisions as a group - how the kitchen, bath, and dining areas should be, where homes should be, landscaping, group meal decisions, group events. In the next phase, this becomes the basis for the lunar version of democracy and law.

    The Moon Agency

    The colonies have become entities that really should govern themselves. Their awareness of the environment they live in, and the tools at their disposal, is so much greater than the ISA, and the colonies are so complex, it is agreed that administration of all lunar installations should be by the people who live there. The local leaders remain bound by the Space Settlement Treaty. That treaty has now been ratified by and extended to almost all nations, as they almost all have astronauts up there.

    The SST makes it easier to decide to grant control directly to the colonists. The colonies are quickly becoming a seat of power. By the end of this phase, everyone can see that. The great good fortune is that the policies of openness and sharing that were established from the outset and have been carefully strengthened over time means that the Earth is comfortable granting the Moon direct control over all that power.

    Their intellectual property has always been open source according to the treaty. They are accustomed to that and have no issue with it. So the nations of Earth don't fear loss of access to the technology developed through the colonies. The SST is also iron-clad regarding access to information about the colonies' activities. Aside from the private lives of the colonists, virtually all events in the colonies are monitored closely and that data is public, and instantly available. If the colonists do anything upsetting, everyone will know right away. Robotic control has also in the end made things more secure. The programming of those robots is public record, everyone knows what they are programmed to do. Nobody can change that programming on their own, it has to go through a process. The robots were designed very, very carefully for it not to be possible to reprogram them outside of that process. In the spirit of Asimov's Three Laws, it is also not possible to make them do something destructive. (They still don't think for themselves, they are fancy automatons, so that is still a feasible proposition.)

    Local Administration

    The MA now runs all the infrastructure in space, much of which is important to businesses and institutions on Earth. Under the Space Settlement Treaty, the MA must keep all the things previously administered by the ISA working properly - the skyhooks and their fleets, all the satellites, telescopes, sensor networks, power plants, and utilities used by Earth-based concerns. As long as they do that, nobody else has any say in what they do.

    The deal for lifetime provision of all necessities the residents had with the ISA now falls on the shoulders of the Moon Agency. Their income from the Moon Fund is meant to cover that, as well as providing funds to satisfy their SST obligations. In addition, they charge for lease of land on the Moon, contracting such leases for a period of between one and one hundred years.

    The Moon Agency chooses to keep the essentials of life free for all people in the colonies. There is almost nobody around they could charge for them anyways, as the residents are exempt. It was the residents who built all the infrastructure of the colonies, and now they keep it running and upgrade it. It was intentionally designed to be open and they very much want to keep it that way.

    So, although such essential things as farming, air and water treatment, power, and communications are now all done by private companies, a large part of their output is bought by the Moon Agency, who then does not charge for public use of it. The highly automated nature of these operations makes this an easy thing to manage - the Moon Agency doesn't expend much of its resources guaranteeing the essentials, and there is no lack. The pervasive monitoring the colonies have always had also makes it easy to monitor usage. It is impossible to hide a level of consumption that would qualify as abuse, so that doesn't happen. It also helps that most of the output of companies providing essential services is both produced by, and consumed by, the colonists.

    The Essential Guarantee

    Food is the case that is really instructive in this system. About a fifth of the food supply is still imported from Earth and that expense is significant. Those foods also tend to be people's favorites. Locally produced foods that are favored over other foods are also in shorter supply than many would prefer.

    Food is allotted to tribes, not individuals. Tribes have their larders, which are stocked by their robots, or carried in by tribe members who have gone personally to select the supply from the greenhouses, gardens, and central stores. These areas are closely monitored by multiple means and there is no way to remove items without it being logged - who, when, what, how much. If a tribe is exceeding its allotment of a food in limited supply, when they leave the storehouse or the greenhouse with it, monitors (in this case actual humans) come and relieve them of it. This happens so rarely and is so easily handled, access to those areas is not restricted. It's just monitored.

    Once food is in the possession of tribes, the great self-regulating dynamic of the tribe system looks after the rest. Tribes look after their own, and are responsible for their own. If one of their number is raiding their fridge, it is up to them to sort that out. They may do so however they like (barring violence), but they may not expel someone from their midst. Tribe is like family, it's for life. They have to figure it out. (The tribe system is examined more under Tribe Life, below.)

    Food that has been prepared, however, can be charged for. As it comes off a ship or out of a garden, that's free. As it comes on a plate, smelling, looking, and tasting great, that can have a price. Prices rarely apply to one's own tribe. They can, but that only works socially in certain narrow circumstances. People from other tribes? Charge them if you want. Also, people can import food on their own dime and charge for that, prepared or not.

    All other commodities and services that are part of the Essential Guarantee are either so easy to provide, or so central to the health of the entire colony, there is no argument about them. Electricity, internet and data services, water, waste processing - the initial infrastructure for these things is expensive, but once built, it lasts a very long time and the maintenance burden is low. Technically, each tribe has an allotment, and use is monitored (because use of everything is monitored, it's just part of the system), but it is so hard to exceed that allotment, it almost never happens. If it does happen, someone goes and checks what the hell they are doing, and usually it is explained to them that it constitutes a business, so either they'll have to stop it, or they'll have to pay for the excess resources they are consuming.

    Medical services and medicine, public health facilities such as swimming pools, gyms, and sports areas, public transit - providing high quality services of this kind for free is in everyone's best interest. It might be harder to do so well without straining the system, if it wasn't for the robots. With the level of technology the colonies have, it isn't difficult at all to organize everything so these things are both free, and of the finest quality.

    Broadcasting and its Impact

    From the beginning the colonists have regularly broadcast shows back to Earth. This has always been one of the conditions of being a resident. A bunch of these shows become quite popular on Earth, even during phase 1. There is a range of them, in many languages. Many residents also do extra shows on their own time, usually video blogs.

    That was the plan from the beginning. It goes a long way to maintaining high public support for the program, and is widely recognized as the principal source of a cultural shift around the globe towards an emphasis on science, and a decrease in nationalist sentiment.

    The most popular shows are sports. These sports are unlike anything on Earth, taking full advantage of the low gravity. Once the long dome habitat at the bottom of Cernan's Promise is complete (now referred to as the Trilobite Hab for its shape) an aerial sport is created. The players fly, flapping their wings by pumping their legs, adjusting wing shape with controls in their hands to maneuver. Their movement becomes closely analogous to that of birds. At first they hold aerial races, obstacle courses, and games of tag, later they develop a ball sport with aerial teams.

    Lots of other kinds of shows are popular too. People on Earth see the colonists interacting with each other, expressing themselves, and living their lives, often in detail. Many become pop icons with real influence, especially those from small countries and developing countries. A lot of colonists earn money in their spare time through the shows they produce themselves, appearances they make in other shows (by virtual presence), products marketed on their popularity, endorsements, or artwork and memorabilia they send back to Earth for sale.

    A lot of the money they earn stays on Earth. They use it to back ventures they have an interest in or help out their families. The rest is for having luxuries shipped to them. This mostly involves foods that are in short supply on the Moon (chocolate, cheese, fine liquor and wine, beef, seafood), fine clothing and jewelry, furnishings, and personal electronics. The food, clothing, and goods shipped up by the MA are high quality and include some of all the listed luxuries, plus favorite items for each resident. But more and better is always welcome.

    Fashions from the Moon spread to Earth. Interest in science education is at an all-time high. Belligerent posturing in politics is at an all-time low. This is all thanks to the intimate contact the people of Earth have with the colonists. The fact the program has led to many advances in technology and science supports this dynamic a lot. In particular, it's clear that even with the vast investments made to build the colonies and the transport systems in space, the break-even point is not far away. Everybody loves space now.

    Privatization and The Moon Fund

    More or less everything that has happened up to this point was anticipated when the Space Settlement Treaty was finalized. It was written into the treaty that once commerce and industry in space reached certain milestones, industry would be privatized, and institutions would be created to facilitate and regulate a market. Towards the end of this phase, that happens.

    Transport, mining, power plants, data transmission, all manufacturing, data collection, farming, and construction are privatized. The entities created are public companies whose shares are traded through the Moon Exchange, which is created for that purpose. Each industry is privatized as a set of companies, not just one, so they are able to compete amongst themselves, and it is feasible for a new company to enter the market. For instance, each power plant becomes its own company, each skyhook, each greenhouse, each factory. The highly integrated and open data infrastructure of the colonies makes this work.

    Proceeds from the sale of shares to the public, which is half of all shares, go to the nations of the ISA who built the infrastructure that made it all possible. The other half of shares go to the Moon Fund, including all voting shares. All such shares are non-transferable and receive dividends quarterly.

    The shares administered by the Moon Fund belong to several institutions. 10% of the shares, which are 40% of voting shares, belong to the ISA. Their votes are cast by their advisory council and administration. 10% of shares, which are also 40% of voting shares, belong to the Moon Agency. Their votes are cast by the director and the council. 5% of shares, being the remaining 20% of voting shares, belong to the Lunar Research Institute, which oversees all the pure research labs and research facilities on the Moon. Their votes are cast by their own council, whose members are drawn from the universities that are members of the Institute, and their senior staff.

    The purpose of this structure is to provide these institutions with the ongoing funds they need to continue to expand our presence in space, and do so in a way that serves everyone's best interests. It creates incentives to provide robust and efficient systems that serve their markets well, respond to those markets, and remain innovative. In essence, instead of a traditional tax structure, the Moon Agency governs the colonies using the 10% of profits of the public companies it receives through the Moon Fund. The ISA has a vested interest in keeping the colonies strong so it realizes more profit for its own operations. The voice of the science community can't be ignored, as they hold the balance of power if the ISA and the Moon Agency are divided, and also they can fund their science projects themselves, instead of needing to go through a government.

    The remaining shares belong to the Moon Fund itself. All dividends earned on those shares must be spent on the projects the holders of the voting shares vote for. These projects must be infrastructure in space.

    The mega-projects built during the next phase are paid for by the Moon Fund under this program. Just as happened with all the infrastructure on the Moon, it is part of the agreements governing these projects that after designated milestones are reached, being a stated volume of commerce and revenue, these structures are to be privatized. Income from their sale and shares in the new companies shall then be distributed just as they were after the sale of the infrastructure on the Moon. Thus a virtuous cycle is created.

    A few key things that are too subject to moral hazard to privatize are administered directly by the Moon Agency, which is a democratic institution. This includes medical services, the justice system (which is tiny), and emergency services (which are almost entirely robotic).

    Some of the created companies work almost entirely for the Moon Agency, as mentioned in Local Administration. This is one of many things that makes a local currency necessary.

    Local Virtual Currency and Contracts

    The colonies are even more saturated with personal computing devices, cloud services, and local networks than the world today. Software for a virtual currency is created and adopted as the standard unit for trade on the colonies. That same software is the basis for forming contracts quickly and easily.

    In the same way that accounts holding virtual currency are protected by the very large number of independent, encrypted records of all accounts and transactions, contracts can be quickly drawn up using a broad range of templates and options. Once signed the record is distributed and encrypted just like financial data is. Contracts are in a different database, as they are public records that anyone can read - at least the basic data. Clauses of a contract may be kept private if desired.

    Phase 4 - Year 36 to Year 50. Residence Program Rounds 5, 6 and 7.

    Fleet Expansion - Planetary Fleets, Toss Ships, Busy Skies

    Gagarin and CP are now working at full tilt, producing on a larger scale, in larger numbers, and a wider variety of spacecraft than is imaginable today. With access to all the raw materials and power one could want, and a highly robotized workforce, manufacture of spacecraft and space infrastructure explodes. More of all the ships already described are made, as many as is called for, ramping up with the quickly increasing capabilities of the colonies and all the projects they are able to dream up.

    The Asteroid Retrieval Fleet targets ever larger and choicer asteroids. It concentrates on carbonaceous asteroids with easily accessible water, which equipment on the Fetchers splits into hydrogen and oxygen to fuel the engines. A few metal asteroids are brought in. Several are used to anchor the Anshar skyhook and the later skyhook constellation. By 5 years into this phase only asteroids over 100 kilotons are being returned, at a rate of dozens per year. By 10 years in, they are several megatons each, coming in at the same rate.

    The Pod ships are mostly phased out in favor of Toss ships (discussed below), while the role of LNCs diversifies, and several types are built for different roles. Small ones with small engines serve the regular runs to the skyhooks, once the electric runways take over most of the delta v burden. Ones with big engines do point to point transport whenever more power is needed, such as when going to a point with no receiving runway, or doing heavy lift. At the end of this phase, a few are mother ships - they are designed to safely transport pregnant women.

    Planetary Fleets

    At the start of this phase, carbon nanotube cable starts being manufactured in bulk, and that means skyhooks get scattered through the solar system, creating the Interplanetary Network. Both things are discussed below. The traffic level it makes possible, especially from Mercury to the Asteroid Belt, means that each of the inner planets is given its own fleet. Mars and Venus each get several toss ships specialized for the separate routes they ply, and each has two Schooners assigned to it - those are ships like the Roddenberry, fast and powerful. The sailing ships of Mercury are discussed below.

    Callisto gets a set of LNC-type vessels for the Jovian system, a Schooner, and a couple of Toss ships as well. The Saturn system gets 2 LNCs, based on Rhea. 2 Galleons (Rumi-class ships) serve those two systems, spending time around Jupiter or around Saturn as needed. A bunch of Galleons shuttle between the outer asteroid belt and the inner planets carrying water ice or metal. Psyche and Ceres get Toss ships of their own.

    Earth and the Moon are brimming with ships going here and there. They skip between the various space stations and skyhooks - transport vessels, private vessels, constructions ships, tugs and service vessels. Toss ships dominate. A fleet of Schooners accumulates.

    Toss Ships

    Once skyhooks come into their own, ships start being made that just go from one to the other, around different worlds. They get almost all the speed they need at launch thanks to how much faster the tip of a skyhook is moving than orbital speed, and roughly the right trajectory by choosing the right moment to release from the tether. For less speed on release, they can let go from a spot lower on the upper tether. On arrival, much of the delta V needed to brake and enter orbit is saved by docking to the upper tether of that skyhook, which is already moving fast enough for the ship to match speeds without braking. It is a question of aiming for the right point in the orbit of the upper tether, where the vectors of the ship and the tether match.

    Skyhooks all have their own Hopper fleet, some of which are now specialized for handling Toss ships. On launch, they hang on to the Toss ship and refine its trajectory with their large nuclear thermal engines, also giving it some more delta V if needed. On arrival, they rendezvous with incoming Toss ships and use their large nuclear thermal engines to do deceleration and docking. As long as the Toss ships can get into a high elliptical orbit on their own, the Hoppers can do the rest.

    In normal operations, though, the Toss ships don't fire their engines at all. The Hoppers do everything. This way, all the Toss ships need is a complement of solid booster engines they can fire in an emergency to ensure they enter any kind of high orbit around their destination world. Such engines are very simple and robust, they can sit unused for years and still work reliably in an emergency.

    Toss ships thus are basically a sturdy frame that can take either container pods or haul bulk cargo in a single hold, a few solid rocket motors, and a bit of kit for avionics and comms and such. They are cheap and fast to build but they last a long time with little maintenance. Their cargo is often more valuable than the ship itself. Their purpose is to move lots and lots of mass quickly, and their design allows their numbers to grow rapidly.

    Toss ships are big, and scale up more as the phase progresses. Traffic of Toss ships also grows quickly. When the Venus, Mars, Mercury, and Earth skyhooks open, fully loaded Toss ships mass up to 12 kilotons. By the time it ends, fully loaded small ones mass 30 kt, the big ones 100 kt. The 100 kt ships are known as Chukwa[?] class. The Skyhooks manage to carry that mass by ferrying arriving ships down the upper tether to the anchor station after they dock, and berthing them there. Once berthed the tether can launch or dock another Chukwa. In unusual cases, multiple Hoppers can be used to maneuver in a Chukwa for docking right at an anchor station, allowing them to rendezvous with skyhooks whose tethers are too weak to bear their mass.

    Passenger Toss ships are globes with shielding made of 1.5 m of liquid ammonia between an inner and outer hull made of aluminum, carbon fiber, and laminated quartz. Only the ones on the Earth - Moon run don't have that, just a solar storm shelter padded with the passengers' own luggage and a modicum of cargo. Cargo pods can also be designed for people, so they can go on cargo vessels. After the space and taken up by the shielding, a large cargo pod still has interior dimensions of 5 m diameter by 37 m long.

    Things that need to get where they are going quickly are placed on the smallest Toss ships, which can get more kick from the Hoppers, and can release from the tip of any launch skyhook. If they need to get there even faster, they go aboard Galleons, or even Schooners, for real emergencies. The giant Chukwas often skip from skyhook to skyhook to reach their destination, which makes their journeys much longer.

    This is one of the names for the World Turtle in Hindu myth. This turtle supports an elephant on its back, which in turn supports the world.
    Busy Skies

    So this phase sees the heavens filling with ships on all sorts of missions here and there. Too many missions to mention, and normal routine business that quickly is not worth regarding as a mission at all. Robots and AI are so reliable that ships doing cargo runs, mining, servicing, and even construction don't have any people aboard. Even passenger ships have a minimal crew, who don't do much besides maintaining a pleasant atmosphere.

    The Schooners travel far and wide through the solar system, visiting everywhere, leaving a trail of observation satellites and rovers in their wake. They even make it to a few Kuiper belt objects. Several probes are sent even further than that, out to the Oort cloud, and to dark Planet 9. Probes launched from Mercury plunge into the sun. People take sky cruises around the Earth and Moon. There are numerous space-based construction projects serviced by various spacecraft. There is so much traffic, that there is official traffic control for the Earth Moon system.

    Carbon Nanotube (CNT) Cable

    Aside from the explosion in activity caused by advanced robotics, CNT cable is the thing that makes this all possible. It also has a profound impact on architecture. In fact, bulk, high quality CNTs have deep implications in almost every technology sector, as does graphene, which should also be producible in bulk if CNTs are.

    The most promising technique for bulk production of extremely long CNTs is widely considered to be chemical vapor deposition. Processes of that kind are likely to benefit from a microgravity environment, which greatly changes fluid dynamics, and a hard vacuum, which makes it easier to produce chemicals of extremely high purity. Here we posit that once humanity manages to fabricate this material in bulk, it can be counted on to have a tensile strength of 30 GPa. Carbon nanotubes have a bulk density of 1.3 to 1.4 g/cm3. (A matrix of another material might be needed to bind them together, but the density of that shouldn't be any higher). This is an estimate of the material properties of the first carbon nanotube cables.[?] To model a skyhook system, it was necessary to choose numbers for these values. It should be noted that as manufacturing techniques advance, it is reasonable to suppose that tensile strengths as high as 100 GPa will be attained. Currently exotic methods, such as cross-linking the nanotubes to produce threads made solely of CNTs, may one day become feasible on an industrial scale.

    The tensile strength of multi-walled carbon nanotubes ranges from 11 to 150 GPa in experimental results. Defects in the atomic lattice are what lowers this strength. See Wikipedia's articles Synthesis of Carbon Nanotubes and Mechanical Properties of Carbon Nanotubes.
    The Skyhook Interplanetary Transport Hubs (SITH)

    Skyhooks are erected all over during this phase. Trips throughout the solar system almost always involve at least one, usually two, and often three. Those for Earth, and the rejigging of the ones for the Moon, are discussed in later subsections. Of the ones in the following list, those at Mars and Venus are constructed first, then Mercury, and finally in order going further outwards from the sun. What takes the longest is transport time of the materials. The CNT cables are so massive it takes several trips to get the whole things to their destinations. This is less of a factor with the inner planets as trip times are shorter and launch windows more frequent.

    Surface and Launch Skyhook Pairs

    Skyhooks are often specialized for either surface operations, or launch operations. The worlds of the inner solar system all have at least one of each. Surface skyhooks have achor masses that orbit higher, so the speed of their foot platforms is slower relative to the surface. That lowers the energy needed to reach the foot platform, or land from there. Launch skyhooks have anchors that orbit lower to take greater advantage of the gravity well of their primary.

    Each launch skyhook is paired to a surface skyhook with a matching orbit, offset by 20° or so. They are in orbital resonance, usually with a ratio of 7:1. For instance, the Venus surface skyhook orbits once for each 7 orbits of the launch skyhook. So, at any given altitude, the launch skyhook is moving 7 times the speed of the surface skyhook.

    The upper tether of a launch skyhook masses 10% to 20% less than the upper tether of a skyhook like the original Gagarin skyhook, that combines both surface and launch duties. For interplanetary skyhooks, upper tethers are by far the heaviest, as they bear heavy payloads and have high accelerations at their tips. The cable mass savings of building paired skyhooks remains significant even though there are 4 tethers instead of 2, and the extra tethers add very useful capacity.

    The savings in some cases are multiplied by handling Chukwas entirely on the surface skyhook. The upper tethers of these skyhooks have much less acceleration, with just enough range to get a Chukwa to the next hop on their trip. If the 100 kt behemoths stick to that skyhook, and the launch skyhook handles ships massing no more than 30 kt, that cable can mass 30% of what it otherwise would. That's the cable that makes up the lion's share of the mass of all the cables in a skyhook pair.

    But most of those savings get reinvested as extra carrying capacity on the foot platform of the launch skyhooks. As they are so short, the cable mass needed to carry each ton of payload is much less than a ton. And there is an imperative to position the center of gravity of the whole skyhook between the two tethers. If it isn't there, and instead is far out along the upper tether because that thing is so heavy, the whole orbit drops down and that is either really wasteful or a disaster that causes the whole thing to crash. However, that same great mass of the upper tether means it takes an awful lot of mass at the anchor shaft to move the center of gravity down within it.

    The efficient thing to do is to put a really heavy foot station on the bottom of the launch skyhook. Ton for ton, that moves the center of gravity many times more than putting more mass in the anchor. And since that is the best move anyhow, now we are free to have two stations on these skyhooks instead of one. Those foot stations are all within 100 km of the surface, a couple are only 20 km above it. There is plenty of mass in the budget to put in excellent water shielding, and still have the mass budget left over for a station that houses thousands of people, plus all the bells and whistles for it to be an observation platform, beam power to the surface, and whatever else.

    Optimizing Inner Solar System Traffic

    The Chukwas are the ones that often use 3 or even 4 skyhooks to get to where they are going. They are too heavy for many launch skyhooks to throw them directly to their destination, in which case they have to hop to an intermediate world. It might take a while for a world to be in range for a decent trajectory, but launch windows can really be stretched by vessels releasing from somewhat higher on the tether than is needed for that destination, so the ship is going faster after release. Also, to go from Venus to Earth or vice versa, it's often faster to launch to Mercury, and then go from Mercury to either planet. Launch windows to either place occur on Mercury usually 3 times a year, whereas launch windows between Earth and Venus happen about every year and a half. There is a greater plane-change to deal with in the case of Mercury, as its orbit is inclined 7° to the ecliptic, but inclining the orbit of the Mercury skyhooks the right way can largely handle that.

    Once there is enough traffic that there is more than one ship on a skyhook at a time, incoming ships need to be ferried down to the anchor station and berthed there until it is time for them to leave. That's generally the best way to do things anyhow, though it's easiest if a ship is unloaded before being ferried, so the cable car doesn't have to haul so much at once. It makes loading and maintenance much easier, and passengers can go back and forth from their ship to the anchor station at will.

    The high-traffic skyhooks of the Moon and Earth have greater demands on them to manage momentum to keep the orbits of the skyhooks stable. Sometimes giant boulders are thrown from the Moon to Earth or vice versa for no other reason than to transfer momentum. Because the ships that come in to these skyhooks are so big and there are so many, the trick of release and retrieve stops being sufficient to quickly adjust momentum when traffic is heavy. Release and retrieve is when momentum is shed by releasing a massive boulder from a point on an upper tether, or added by releasing it from a point on a lower tether. Those boulders are retrieved when their orbits bring them back to the skyhook. Though there are dozens of such boulders on each skyhook and they can mass up to a kiloton, more momentum can be added or subtracted by catching a boulder thrown from another world, or throwing one to another world. The Earth and Moon play catch this way to trade momentum when needed, and those boulders sometimes mass 30 kt.

    Adding Anchor Mass: the Mining of Phobos

    At first, the anchor masses of these skyhooks aren't very big. Once they are set up, their fleet of Hoppers, LNCs, and a couple of Fetchers, get to work adding mass to the anchor whenever possible. Maintaining their orbits takes a lot more fuel and trickery with passive masses until the anchors are many times heavier than the cables, and the heaviest ships that come and go. The Fetchers go after anything that comes in range on a convenient trajectory, the LNCs use all their spare time to ferry mass made of whatever to the foot platform, to be taken up and added to the anchor. Accumulating mass this way is far too slow, though. It would take a long time to really stabilize the skyhooks using only what the local fleets can bring in. The issue is that Venus has no LNCs because the surface is far too hostile to send LNCs down there, Mercury doesn't have many asteroids passing by that are easily caught, and at Earth, even with the huge drop in the price of launching to orbit caused by Anshar, shipping rocks to orbit makes no sense.

    So, bits of the moon Phobos are spat to Venus, Mercury, and Earth to pump that mass up way faster. Phobos is, in fact, the anchor of the surface skyhook of Mars. It masses 10 million megatons, so it can spare a few thousand megatons for miscellaneous ballast and shielding material in projects elsewhere over the coming decades. Its surface is conveniently composed of dust and small rocks. The biggest issues with mining it for these purposes is keeping the dust contained so it doesn't form a haze around the moonlet that takes forever to settle. Once it's bagged, the bags gets thrown off the end of the upper tether of Phobos on the fast track for Earth, or Venus. We are talking bags of dust and rubble massing 100 kt. The Hoppers refine their trajectories for their destinations before returning to Phobos, and Hoppers on the other end do the same thing, shepherding the bags in to the receiving skyhooks. As the Phobos tether can throw to Earth and Venus good and hard, launch windows are long and trip times are short. Hundreds of these bags can be tossed each time either destination planet is in range. Mercury can get deliveries by the Earth launcher skyhook re-throwing bags its way.

    Thanks to this supply, the anchor masses of all the skyhooks of the inner solar system are piled up to 20 megatons by the end of this phase, and a few exceed 50 megatons.

    Skyhooks of the SITH

    All of these skyhooks are made of CNT cable. The figures shown are for the configuration attained by the end of this Phase. All of them will be operating long before that, but with less capacity. As more cable is woven into the tethers, capacity increases.

    Table Details

    In the rows that show tether mass, this is the mass of just the CNT cable. Those numbers show the mass first in metric kilotons, and then in the brackets, as what multiple it is of the payload mass. Really the payload mass should be multiplied by 1.05 to account for the mass of the climber, the foot platform, and all the infrastructure on the tether for maintenance and power transmission. It also doesn't count the mass of the shaft that joins the two tethers together, around which the anchor mass is built up. That probably adds another 1% or so to the total cable mass. These things aren't done for the sake of simplicity. The grand total of both skyhooks also includes the mass of the foot station on the launch skyhook. As that mass directly bears on the mass of the cables and the strain on them, it is included there. Anchor mass uninvolved with bearing the weight on the cables has little relevance to the overall structure, other than it affects the center of gravity of the whole thing. It goes up and down over time, mostly up, and adds stability in general as it grows.

    Tether figures use a safety factor of 2. That factor accounts for what a tether needs to operate safely even despite wear and tear, manufacturing defects, and damage due to any micrometeoroid strikes. Safety factor of 2 means the taper ratio used is the square of what it would be if it was just barely enough to bear the loads on it. In that case, even if the cable's tensile strength was reduced by half, it would still be just strong enough to bear the weight on it. All skyhooks are made of an open weave of cables known as a 'Hoytether' weave, after Robert Hoyt of Tethers Unlimited. That design makes it easy for maintenance carts to weave in new cables when they detect a weakness on a cable. This may mean that a lower safety factor would be just fine. The mass of a tether changes drastically with a change in safety factor, so that would be a big help. Thus bear in mind that as in all things here, this number is estimated on the conservative side.

    lolololololol Mercury[?] Venus[?] Earth Moon Mars Callisto Titan
    Surface Skyhook
    Foot, km 20 100 100 20 50[?] 20 800[?]
    Anchor, km 10000 7000 6500 7000 5980[?] 4900 10000
    Tip, km 45000 15500 14000 30000 23000 15000 20000
    Lower Tether
    Mass, kt (xP) 31 (5.16) 51.1 (17.0) 54 (18.0) 22.8 (1.14) 275 (2.75) 5.7 (0.57) 77 (0.08)
    Payload, kt 6 3 3 20 100 10 100
    Foot Speed, m/s 263 2352 2798[?] 151 785 329 227
    Upper Tether
    Mass, kt (xP) 249 (2.49) 287 (2.87) 296 (2.96) 52 (0.52) 327 (3.27) 29 (0.29) 7.7 (0.077)
    Payload, kt 100 100 100 100 100 100 100
    V(inf), m/s 4983[?] 6142[?] 6200[?] 2664[?] 5746[?] 2179[?] 1227[?]
    Total Mass, kt 152.5 338.1 350 74.8 602 34.7 84.7
    Launch Skyhook
    Foot, km 50 100 100 20 50 20 800
    Anchor, km 1714 1000 929 1000 854 700 2000
    Tip, km 10000 6500 6350 15000 9000 11000 20000
    Lower Tether
    Mass, kt 47 (0.47) 30 (0.25) 97 (0.23) 11(0.11) 29 (0.13) 3.9 (0.04) 5.2 (0.05)
    Foot Station Mass,[?] kt 90 110 400 80 200 90 90
    Payload, kt 10 10 20 20 20 10 10
    Upper Tether
    Mass, kt 551[?](5.51) 522 (17.4) 2190 (21.9) 606 (20.2) 1200 (20.0) 184 (6.13) 297(2.97)
    Payload, kt 100 30 100 30 60 30 100
    V(inf), m/s 6635[?] 9705[?] 10146[?] 8150[?] 8895[?] 6469[?] 5285[?]
    Total Mass, kt 688 662 2687 697 1429 278 392


    The Mercury colony will be at the north pole, so the surface skyhook has a polar orbit. The launch skyhook needs to have an orbit inclined 7° from the equator or it is rarely aligned for launches to other planets. So, ships coming and going are all going to have to deal with an 83° plane changes when moving between skyhooks. Being able to do the plane change between two upper tethers should reduce the fuel needed compared to plane changes without that assistance.
    Because the surface skyhook has a polar orbit, it can't be used to handle launch of Chukwas. The launch skyhook has to do it all. It has to be able to bear 100 kt at its tip.
    A skyhook that combined the tasks of launch and surface ops, and had similar capacity to the skyhook pair shown here, would need to mass about 1008 kt, making it 145 kt heavier than the two skyhooks. Even then, its lower tether would only be able to support 3 kt, while the lower tether of the launch skyhook can bear 10 kt, albeit its foot is moving much faster and likely there are few cases where it makes sense to use that tether. Not only does a skyhook pair take less material, a spacecraft going up from the anchor station to launch from the launch skyhook only needs to travel half as far. There are twice as many berths, and 8 times as many launch opportunities. It might be a bit tricky to hop from the surface skyhook to the launch skyhook and vice versa, and it takes a little fuel. Overall though, a big plus to have skyhook pairs instead of one that does it all.
    The Earth spins at a velocity of about 450 m/s at the equator, so a launcher would only have to gain speed of 2.35 km/s to reach the foot platform.
    Actually, the average distance of this foot is 192 km, and at apoapsis it is 334 km. Which is a pain, but worth it. This is because its anchor is Phobos. See note below.
    The anchor in this case is actually the moon Phobos, which orbits at an average distance of 5980 km from the equator of Mars. But its orbit is rather eccentric, so sometimes it is as close as 5838 km. This is why the foot of these skyhooks can only come down to 50 km, even though since Mars has such a thin atmosphere, and Phobos is such a giant reservoir of momentum there is no need to think about performing orbital corrections to compensate for drag. In fact, the orbit of the launch skyhook will be matched in eccentricity, to make it easier to keep them far apart with little orbital maintenance. However, as the orbit of Phobos is inclined 26° to the ecliptic, a plane change of 26° will be needed to hop to the launch skyhook, as it is best for it to be aligned to the ecliptic to minimize the energy spacecraft launched from it need for plane changes.
    Titan's atmosphere is so dense (1.45 times Earth's at its surface), and its gravity so low (0.14 g, similar to the Moon), that it extends to a great height. Even at this altitude, the foot platform will experience measurable drag that will occasionally need to be corrected for. Vehicles from the surface headed for the foot platform will be able to use lift to get most of the way and require little fuel to cover the remaining distance.
    To place the center of gravity of the launch skyhooks where it needs to be - at the anchor station - the most mass efficient method is to add mass at the foot. If this isn't done, the much greater mass of the upper tether puts the center of gravity inside that tether. A very heavy anchor station goes a long way to fixing this issue, but it isn't enough, and at any rate a solution is needed while that anchor mass is being accumulated. Making a cable capable of sustaining the heavy mass of a large foot station is cheap, it takes only a fraction of a ton for each ton of payload. And then a great facility can be created at the foot, that takes advantage of the proximity to the surface for a great view and reduced radiation shielding needs.

    The figures in this row show a rough estimate of how massive the foot station would need to be to place the center of gravity between the upper and lower tethers. The analysis needed to properly estimate this is far beyond my math abilities and will need to wait for a time when someone else can give the question the attention it needs. A precise solution for this is impossible due to the nature of the calculation. Experimentation with an actual system will be necessary to derive a functional formula that gives a really good approximate solution (but not an exact one).
    This isn't enough to get to any other world. It's about 2/3 what's needed to get to Venus, but would rarely be used for that, as this skyhook is in a polar orbit. Venus would rarely be properly aligned with it for a good trajectory to result from a launch from this skyhook. (Mercury's orbit is quite eccentric for a planet, and when it is at aphelion it would be able to launch to much closer to the orbit of Venus, but Venus is unlikely to be there when that ship arrives.) This upper tether exists to assist with transfers between skyhooks, and to give the sailing ships an initial boost.
    This is a bit more than is needed to reach Mercury and Mars, and plenty to reach Earth.
    Plenty for going to Mars or Venus, almost enough for Ceres
    Three times what is needed for Earth, lots of extra going to Venus or Mars
    Twice what's needed for Earth, Vesta, and Ceres, plenty for Venus, almost enough for Jupiter
    Double what's needed for Ganymede, almost enough for Europa
    Twice what's needed for Hyperion, just enough for Iapetus and Rhea
    Gets you most of the way to Venus. Everything coming and going from Mercury will need to make use of the sailing ships.
    Twice the speed needed for Earth, Mercury, or Mars. Vesta or Ceres with speed to spare.
    Earth is of course the hub of everything, and Anshar's sister skyhook fits that role. It throws things so hard, you can launch for Venus, Mars, or Mercury anytime and have a short trip, get to Jupiter anytime and shave some months off transit , and just reach Saturn.
    The sister skyhook of Gagarin throws hard to Venus or Mars any time. Ceres is also a short trip, though sometimes a little fuel will be needed to maintain the schedule. Mercury is in easy reach, Jupiter is just in range.
    Really fast trips to Earth any time. Almost the same for Ceres. Twice the speed needed for Venus and Jupiter. Mercury just in range.
    All Jupiter's moons in reach. (Because Jupiter's gravity is so strong, this actually takes a lot of speed to achieve. This skyhook can throw to Jupiter itself, but it is on the edge of its range.) Twice the speed needed for Mars. Earth and Venus with plenty to spare, not much margin for Mercury.
    All Saturn's moons in range. Twice the speed needed to reach Saturn. Throws hard to anything closer to the sun. Laughably overpowered for reaching Earth.
    Auxiliary Space Elevators

    Ceres already has a space elevator, and during this phase it is expanded so it can throw fast to Mars or Jupiter. Most of the Chukwas that come and go hop first to one of those planets and then hop again once or twice to get to their destination. Ceres is less important now for water, and more for its valuable salts - ammonium chloride, sodium carbonate and others. It also seems to have graphite, which would be very valuable indeed. During periods when there are better trajectories from Ceres to the inner planets than from Callisto, Toss ships from Ceres partly carry water, otherwise Callisto is the major shipping point for water.

    Psyche is given a small space elevator too. Psyche (more properly known as 16 Psyche) is an asteroid made of metal 200 km across. Solid mixed metal, mostly iron. Since it is purely metal, it is a convenient place to set up a small plant to refine out the other metals dissolved in the iron. There is so much iron in small asteroids collected by the Fetchers around the inner solar system, it has almost no value. The semi-conductors and platinum group metals dissolved in it though, those have value. Even the copper in it does.

    Its elevator can bear the mass of a fully loaded Schooner - 3 kilotons. It is able to throw ships to Mars or Jupiter with a little speed to spare. It has a mini-Toss ship of its own rated for its maximum payload. Mostly it loads it with only a few hundred tons or so of metals at a time, but by the end of this phase it is able to load it to the brim, and another new one just like it. With each run the Toss ships return with more mining equipment.

    Anshar Skyhook

    Anshar is the surface skyhook for Earth. It is the first skyhook built out of CNT cable. That cable was spun in Gibraltar's manufacturing sphere using carbon extracted from carbonaceous asteroids. Soon after the skyhook opens, another CNT facility is constructed on its anchor mass. That facility then provides the cable for expanding Anshar, and for the rest of the skyhook constellation around Earth that springs up over the coming years.

    The initial anchor mass is a metal asteroid massing 300 kt, and then carbonaceous asteroids are tacked onto that. Within 2 years the anchor masses over 2 megatons. By the end of this phase, both it and it's sister skyhook have anchors massing over 20 megatons.

    An impressive complement of high-specific-impulse VASIMR and Neumann drives are attached to its tip platform and its anchor. In addition to solar panels, there are nuclear reactors providing electricity for the drives. Those reactors can also power nuclear thermal LANTR engines in an emergency for quick orbital corrections or avoidance maneuvers. In fact even the high-Isp drives aren't used much, and rarely at full power. Most orbital correction is done with the release and retrieve and by playing catch with the Moon, as described above under Optimizing Inner Solar System Traffic. The drives have to be there in case of emergency. Sometimes they are useful for helping a troubled ship come in to dock, by putting the dock in front of it.

    As the Van Allen belts have been drained, they are no issue for Anshar. It and its sister are tilted 25° to the equator to put them on the plane of the ecliptic.

    High Volume Traffic on Anshar

    The foot of Anshar Station moves above the surface of Earth at only 2.4 km/s. That is less than a third of the speed needed to attain orbit. The first stages of rockets get up to speeds around 1.5 to 1.8 km/s during launch. Most of the ships arriving at its foot platform are two stage rockets designed for complete reuse thousands of times. A few use other technologies and are also completely reusable. The market for rockets that fly directly to space disappears almost completely.

    Scramjets would be another possibility for reaching the foot platform, but they are much more demanding technology. Standard rockets are likely to remain the cheapest and most reliable option. Air launch might become more attractive. The impact on launcher design of the low speed and low altitude of the platform would be great.

    Whatever the cheapest launcher design for high volume traffic is, the cost of launching a kilogram to Anshar would be a tiny fraction of that cost today. Building Anshar of course was expensive, but maintenance and repair of it is cheap. This is true of all the skyhooks. The price offered to get from the surface of Earth to Anshar Station quickly drops to US$30 per kg. The price from there to a lunar colony is another US$30 per kg.

    Cargo coming in from Anshar costs considerably less. Slag left over from other processes happening on the anchor is used to make simple disposable heat shields, and cargo pods fitted with such a shield are simply dropped from the foot platform to splash down in an ocean. The pod has a beacon so it can be recovered, and parachutes to brake its descent during the last kilometer or two. The pods don't weigh very much, once the heat shield is popped off and allowed to sink to the bottom of the ocean. A standard cargo flight returns hundreds of them to Anshar Station. A standard pod for 3 metric tons of cargo weighs only 50 kg when empty, and without its heat shield. Cost per kg for that incoming trip is only US$2.

    A hollow sphere of metal can be dropped for even less. Stick a disposable heat shield on the bottom and give it a cheap beacon, and forget about the pod and the parachutes. Mining asteroids for any metal with a price higher than a few dollars a kilogram then becomes competitive.

    Further aspects of Anshar are discussed under the Anshar Station section.

    Earth Skyhook Constellation

    Construction on the sister skyhook of Anshar, which is the launch skyhook in the table above, starts right after Anshar is complete. It is named after another ancient sky god, Hepit. Its upper cable masses 2.2 megatons all by itself, far bigger than any other cable. To seat the center of gravity of the skyhook at the correct point, a foot station is built on it that masses 400 kilotons.

    Then 10 mini-skyhooks are built to complete an observation and telecoms infrastructure for Earth. 4 fill in the rest of the plane Anshar is in, 72° apart on it. The other 5 are in a plane that complements that, with an ascending node exactly on the other side of the planet. They have orbital periods that match Anshar, circling the Earth every 4 hours and 15 minutes. They can only bear spacecraft massing 200 tons, and their upper tethers are only 1000 km long.

    These skyhooks take over a large fraction of Earth's internet and telecoms service. The skyhooks are bases for servicing and launching of satellites, taking over those duties from the free-flying space stations, as access to them is cheaper and easier. Small Hoppers stationed on them do orbital debris cleanup duty. They are observation platforms with a broad suite of instruments - telescopes across all wavelengths, radar, lidar, monitoring of the magnetosphere and radiation around Earth, gravimetry.

    Together, this set of skyhooks eliminates the necessity for most other satellites in Earth orbit. That allows the vast majority of them to be cleared away so the skyhooks need not worry about colliding with them. Deals are made with operators of satellites being cleared to move their operations onto the skyhooks. Debris in orbit has been mostly handled by the time these events occur and satellites have been slotted into orbits posing no risk to the planned skyhooks for the previous 15 years or so.

    The space stations are moved to orbits just in front of and behind Anshar, where shuttles can very easily hop between them and the skyhook.

    Electric Runways, and Rejigging the Lunar Skyhooks

    As shipping volumes increase, and construction at scale becomes widespread, new shuttles are scaled down from the size of recent generations. They are for a fixed system that launches them at a high cadence. They can still haul up to 60 tons, but their engines are smaller, and no longer nuclear. They have enough thrust to overcome lunar gravity, with a thrust-to-weight ratio of around 1.5 when fully loaded. When they launch to Gagarin, they lift off from a runway that accelerates them up to the needed speed and throws them off the end in an arc that peaks just above the altitude of Gagarin's foot platform. Their engines fire only to do the maneuvering for matching vector and speed with the platform. During normal operation, the launch is so precise their engines barely fire at all as they come in and dock. On return, their engines brake their descent, and the runway brakes their horizontal motion.

    This runway is 15 km long and sloped 60° at the end. The speed at lift-off is about 300 m/s. There is another runway running north-south for traffic with polar skyhooks, with the same length and upward slope at the end. There is also an east-west runway designed for launch to Magnificent Desolation. The horizontal speed needed to reach its foot station is 860 m/s, so it is longer, with less of an upwards slope - 27 km and 17°.

    The landing gear on the shuttles is powered through electrical contact made with a rail down the middle of each runway. That power is what accelerates them up to speed, through electrical motors that turn their wheels. After the shuttles have loaded and unloaded at the foot platform, they wait until the skyhook's next pass over Lalande, and then drop off. They return to the same runway, braking their descent with their own engines and touching down at the other end. On landing, electrical contact is made with that same rail, and as their wheels are slowed with magnetic braking, the generated energy is passed back into the system.

    It becomes typical to launch a bunch of these shuttles in quick succession while Gagarin is in range, up to 50. They can be launched at a cadence of up to one every 10 seconds. Each one docks in one of the docking spaces in the vertical stack that now extends up the foot of the skyhook. They are called Geese for the organized way they usually fly all in a row.

    Landing gear modules for the big LNCs are made so they can use these runways too, when delivering objects too big or heavy for the Geese, to Gagarin, polar skyhooks, or Inukshuk. The electric current infrastructure is sized to accelerate a fully loaded LNC up to the speed needed to rendezvous with Maggie's foot station. In fact, it is sized to launch a mother ship to Maggie. LNCs are designed for point to point service anywhere on the Moon, if need be. Though they get to places whenever possible by hitching rides on skyhooks, sometimes that is too slow. On such missions, their landing gear can be removed to maximize their payload capacity. In that case, they lift off and land vertically, as they did in the past.

    Gagarin is moved to a higher orbit, at 7000 km, and all the polar skyhooks are raised to the same altitude to maintain their staggered orbital rhythm. Magnificent Desolation is converted to the launcher skyhook. For this purpose its orbit is lowered to 1000 km, so it passes by Lalande 7 times for each time Gagarin passes by.

    Over time, all the lunar skyhooks are converted from Zylon to CNT. The maintenance carts work on that as they are able. Maggie has to be changed so much that is all done during it's conversion to the launch skyhook.

    Great Sailing Ships
    The sunlight at Mercury is ten times as intense as at Earth, so a sail that catches that light and uses it to push a ship can gain or shed speed ten times faster. Building on experience gained when probes and small ships were sent to Mercury to test solar sails, truly giant sails are made and connected to a sort of tug ship. These tug ships attach to the Toss ships coming and going, and stay connected until they have imparted the speed they need to get to their destination in good time. Then they detach and tack back to Mercury. It is a delicate business, moving around those sails so they pull on vessels as desired, and never get tangled in anything.

    The sail tugs almost never go beyond the orbit of Venus. They aren't needed that far out.

    Laser Propulsion

    A laser system is built at Inukshuk that can be used with a special version of the solar sails (that can handle extremely intense light) to push small probes to relativistic speeds (speeds fast enough to be regarded as a fraction of the speed of light). A series of trials is done with it. Work is done on how to use the extensive infrastructure now spread across the solar system to deploy tools to keep lasers tightly focused on the sails longer. Tests using lenses orbiting several AU from Earth are done, to refocus the beam once the probe passes by. After a while, a second, and then a third laser is built and placed in orbits further from the sun. Schooners reposition the lenses and lasers between trials to align them such that they can focus or fire on a probe once it passes their position.

    This is done in preparation for interstellar missions. A capacity to accelerate probes massing a kilogram to 15% of the speed of light is created. Though the probes must be small, many can be sent. At the end of this stage, many such probes are launched to our closest neighboring stars.

    End-to-End Robots

    Robots move from being able to execute a step-by-step plan, to being able to make a plan that will satisfy a set of objectives they have been tasked with fulfilling. The first mega-project they are then tasked with is the construction of Lalande City. The robot team that does it is presented with detailed engineering plans for the city and some parameters for the resources they may use, and told 'go'.

    They start by building the new factories for the various materials the city requires. They prototype the robots needed for all the different construction tasks, test them, improve them, and prototype again until they are satisfied they meet suitable standards. Then they build the factories for those robots, and the power plants needed to run them. The first robots stabilize and seal the interior of the crater, prepare the rim with the foundation for the dome that will cover it, and the foundations of all the towers dotted throughout it. The next wave starts building the central towers, and uses them to support the frames of the dome sections. The dome frames and the towers both are slowly expanded, upwards and outwards, until all the towers are their full height and the full armature of the dome is sitting atop them, and the rim structure ringing in the crater. A temporary membrane is used to seal the dome and a thin atmosphere is pumped into the crater, so that the millions of glass sections for the dome can be laid in their frames and built up layer by layer. More power plants are built, and all the infrastructure to supply the city - air, water, thermal control, waste recycling, supplementary greenhouses, telecoms, computation, transit systems, centrifuges, airlocks, lighting, monitoring, emergency services... The city is pressurized up to a full atmosphere and all systems tested.

    They lay down topsoil over the crater's interior, setting up terraces and mesh to retain soil on slopes. They plant initial cover crops and test the artificial waterways, the intricate web of irrigation and drainage pipes, and the artificial rain system. Once satisfied, they plant all the trees, bushes, vines, and cacti - anything that lives for years. They build the roads and paths all through the gardens. Humans help a bit during this part, where they want to put in a few personal touches or enjoy the gardening.

    At the end of this phase, 15 years after the project started, the city is ready for habitation and rated for a population of a million people. As the robots finish each phase of construction, the ones specializing in that phase are reassigned to the other mega-projects being undertaken elsewhere - the build Anshar Station, and then Hepit Foot Station, then the cylinder colonies of Magnificent Desolation. The factories that built those robots first refit or replace the robots working in the factories of Cernan's Promise, and expand those factories to help supply the mega-projects. Then they build new robot crews so they can build the cylinders for all the other skyhooks.

    Once all these robots finish, shortly into the next phase, they need to be assigned to something else. Some are instructed to keep building more cities on the Moon. Those next cities start without an initial colony nearby to support the initial phases of the project, or even detailed plans. But that's okay. They figure out how to build that initial base for operations, and how to adapt the previous plans to the new craters. They start turning out a new city every decade, rated for populations of one to two million. The implications of all this are discussed in Birth of Worlds

    Robots become sort of invisible hands that look after all the details, leaving humans free for creative, intellectual, and spiritual pursuits. They do not develop wills of their own.

    Lalande City

    The dome over Lalande Crater is 23 km across on average. The rim ring is 250 m wide, rises 400 m above the rim, and extends 300 m below it. It is heavily reinforced with thick cables that connect to the cables of the dome, and anchor them to the bedrock through shafts at hundreds of points. There are over 80 towers spread throughout the crater that anchor the dome at those points, containing the outward strain of the atmosphere pushing against it. Though the total thickness of the laminated glass of the dome is 3 m, it is still only a fraction of what it would take to counterbalance the pressure of the city's atmosphere. The towers are built around central cores of CNT cable. They are very solid structures of metal, glass, basalt, and composites capable of supporting the dome even if the city loses 95% of its atmosphere. In the center of Lalande they are 5 km tall, near the rim they are 1 km tall. The dome has been built around Cernan's Promise, now it is entirely indoors. It's buildings are preserved for history.

    The towers and rim are where people live in Lalande. The ground is set aside for 'nature'. It has a few facilities for physical activity or public gatherings, but 95% is vegetation or water bodies. Institutional buildings and hospitals are dotted around the crater floor, but they are subterranean, built inside artificial hillocks, hobbit style. Maintenance facilities are all truly subterranean, and inhabited solely by robots. Factories and research facilities are all outside the rim, as are power plants and supplementary greenhouses. Factories are also clustered along the tunnel to the space port 35 km northeast of the city.

    Very little of the vegetation is ornamental. It all produces something of value. Trees bear fruit and nuts, bushes are herbals or yield berries, vines have edible roots or fruit, whatever doesn't has medicinal bark, roots, or leaves, or perhaps is a host to a highly valued fungus or edible insect. The ecosystem requires constant adjustment, but only in ways subtle enough that to the untrained eye it is self-sustaining. Small vegetable gardens are scattered all over. Flower plots are set beside path intersections, benches, fountains, and plazas. Small animals and insects live in this groomed wilderness. Some are for food, some are pollinators, some balance the ecosystem.

    For the most part, it isn't identifiable as farmland, though it all is. The robots don't plant single crops in neat rows, they mix everything together in careful ratios according to what is the best fit for the local soil and terrain, guided by the ecosystem engineers that oversee them. Lush natural ecosystems are imitated as closely as possible. They are able to monitor the environment so carefully that all animals roam free and live pretty natural lives - until it's time to roast them for dinner. In that case, the needed number are promptly captured and cleanly killed. Farming robots work so intimately with the ecosystem they almost seem like part of it. The colonists thus don't refer to it as the gardens or the farms, they call it the countryside.

    Once the countryside matures it is able to supply most of the population's food. The air has 2000 ppm carbon dioxide. The rains and irrigation are meted out for best growth. Strings of tiny lights woven into vast nets are carefully spread over everything during the lunar night to provide enough light energy to sustain all the plants. Each patch of these light-blankets provides light for stretches of 8 hours, and then switches off for 16, all through the night. There are no pests, no infections, no droughts, no frost, no storms, and no winter. Most woody plants and vines provide a harvest three times a year. Those harvests are staggered by design so that the supply of fresh produce is almost constant.

    A few key crops are grown in the supplemental greenhouses, mostly grains and legumes. Those greenhouses are completely optimized for maximum yield of whatever crop is in them. They have little free space and feel like factories. For maximum crop density, they are grown in trays that are supplied with sun by fiberoptic cables during the day, and by LEDs at night.

    In a similar fashion there are water and air treatment plants that use bacteria and algae to filter out toxins and disease agents. The algae tanks have light piped to them, the bacterial sludge is kept warm with waste heat.

    Broad suspension bridges link the towers, wide enough to be landscaped with gardens of their own and have kiosks and cafes dotted along them. They are spaced every kilometer up the towers. The arches between towers that support the dome also have several levels of walkways hanging beneath them.

    It takes a decade for the population of the city to fill out. While it does, the countryside fills out with it, the trees rising and thickening into forests, moss covering rocks, vines climbing the towers.

    Power Supply

    A mix of power sources is developed for the Moon. Nuclear reactors run on thorium and uranium, solar thermal plants produce power while melting regolith to extract volatiles and produce molten feedstock for production of glasses, ceramics, and metals, microwave rectenna grids receive power from orbital solar wings. Flywheels are used to smooth out the matching of supply and demand.

    Anshar Station

    As mentioned in the Anshar Skyhook section, mass is added to the anchor of Anshar as quickly as possible. Much of it arrives as rubble - fragile rubble pile asteroids are intentionally allowed to disintegrate during transport so they are easily mined to extract their carbon and water. The metal asteroid that arrived first and formed the initial anchor during skyhook construction is slowly processed to recover the metals dissolved in the iron that forms 92% of its mass. All of that metal is in high demand, but there is so much iron, and so many of its traditional uses have been taken over by other substances, it has little value. While it is still molten, at the end of the refining process, it is drawn into rods of between 10 and 100 m in length, whose ends are fused together into a gigantic latticework of tetrahedra. This latticework extends outward from a section three-quarters of the way up the enormous stone shaft bridging the center of gravity of the skyhook, where the upper and lower tethers are joined together. It is employed as bulk shelving and support frames for processing and fabrication units that operate within the lattice.

    As asteroid material is refined into carbon, water, pure metals, and metal oxides, these products are warehoused in the lattice. Slag, tailings, unused waste rock, and unused particles from gravel to dust, are carefully organized and stored in the lattice too, in case they prove useful later. They are archived according to composition, particle size, and origin. This forms the bulk of the mass of the anchor. A significant fraction of the mass is bags of compacted dust from Phobos.

    The stone shaft is a tube formed of a matrix of slag with fibers of high-strength glass and CNT mixed into it. Cables of CNT also run through it from end to end, and the tethers are fixed to the points where these cables protrude from the ends of the shaft. It is 100 km long and 50 m in diameter, with a hollow core 30 m wide. The climber cars travel through that hollow core on their way to the transfer hubs along it - Anshar Station, the industrial and shipping docks on top of the lattice, and the passenger spaceport just above those. The section where the iron lattice attaches to it is 5 km long.

    The center of gravity of the skyhook always stays within this length. It is designed to support any kind of forces either tether could ever be subjected to, and provide rigid support to all the structures built around it. Anshar Station is tucked under the lattice. The bulk in the lattice shields the station from radiation and impacts. It turns and extends downwards outside the station to protect its sides as well as its top. Only the station's bottom is unobstructed, and that side is mostly protected by the Earth itself.

    Anshar Station is shaped roughly like a punctured puck. It is 1 km in diameter, 250 m high, and the anchor shaft pierces the center of it. The top side, facing the lattice, arches shallowly between the central shaft and the outer sides. The side facing Earth arches much more deeply. That side is almost entirely glazed, receiving lots of light from the Earth below.

    The station rotates to simulate 0.8 g on its outer rim. Every 50 m from the rim to the hub there is a floor ringing the interior. Each successive floor is narrower than the one below, leaving more open space between its edge and the glazing. This allows more of the view to reach more of the interior, and better distribution of the sunlight piped in through clusters of fiberoptic cables bunched around the hub. Sunlight shines down from their outlets. The hub of the station rotates around the shaft of the skyhook a bit slower than once a minute.

    Anshar is mostly a workplace. People usually come for stints of between one to five years, but almost nobody moves there to stay. Most people come for work or pleasure, and spend only a few days to a few weeks there.

    Manufacturing on Anshar

    Several double spheres like the ones at the Gagarin Shipyard are built on top of the lattice. All the manufacturing techniques pioneered on Gagarin are shortly also being done at Anshar. Gagarin concentrates on spacecraft and space construction equipment. Anshar gets into all sorts of things.

    As mentioned under Anshar Skyhook, mining of all sorts of metals is profitable at Anshar. As operations expand and economies of scale take hold, even more become profitable. But not much bulk metal is sent to Earth. It is used to make things that are much more valuable, and those things are shipped to Earth - or to the Moon.

    Anything that can be made from the materials available in asteroids, can withstand deceleration forces of roughly 10 g, and has a value higher than about US$20 per kg, is a viable option for manufacturing on Anshar. This represents a very wide range of technology.

    And here we are only talking about the market for Earth. All sorts of things are both more valuable deeper in space, and cheaper if bought from a company on Anshar instead of an Earth-based competitor. Companies at Gagarin and Cernan's Promise have an advantage here too, of course.

    Hepit Foot and Anchor Stations

    Hepit is the 400 metric kiloton foot station of Hepit Skyhook, Earth's launcher skyhook. It is a half dome made of a honeycomb of cells of laminated quartz filled with water, 1.5 m thick, measuring 300 m across and 150 m high at the center. Its floor and internal structures are made of plastic and aluminum alloys reinforced with graphene or CNT. The lower tether of the skyhook pierces the dome at the center, and its cables are used to support a building that spans the middle 100 m of the dome, and extends through its floor. That building descends 100 m below the floor of the dome, and rises to 50 m from the dome itself. Hanging below it are the docks for the craft coming and going from that tether. A tube at the core of that building cuts through the whole dome, so the climber cars can pass through it to reach the docks, load and unload, and transfer people and cargo to the skyhook's anchor station.

    On top of the building, and in the whole area around it, is garden and leisure space. There are many swimming pools and sport areas. Hepit Station is a resort more than anything else. Because it moves at a large fraction of orbital velocity, the pull of gravity is only 0.3 g inside it. It orbits every 100 minutes. At its altitude of 100 km, it offers a gorgeous view of the Earth below. With a sunset or a sunrise every 50 minutes, it has an oddly timeless feel. It can accommodate up to 40,000 people.

    The foot stations on the launch skyhooks of all the other planets in the network are of a similar overall design, though much smaller. When first built, the mass needed at the foot is just a bunch of rocks, until the proper station can be built.

    Hepit's anchor station is all business, designed almost entirely simply to facilitate traffic between Hepit and Anshar. Most traffic on Hepit is either people or cargo arriving from other worlds and headed to Earth's surface or the manufacturing in the lattice of Anshar, or leaving on the way to other worlds. In all these cases, a hop from Hepit to Anshar, or vice-versa, is involved. Traffic to and from Earth's surface occurs almost exclusively on Anshar. The first waystation on the upper tether is a release point for Hoppers headed to Anshar, that gives them an orbit with an apoapsis at the altitude of its main docks. Hoppers coming in from Anshar release from a similar waystation that gives them a periapsis at the altitude of the anchor docks of Hepit.

    Most of the activity at the station is simply robots moving back and forth in the hollow core of its stone shaft, ferrying cargo and passenger pods. The only bits of it that are pressurized are a few small maintenance modules and an emergency shelter. Three-quarters of the way up the anchor shaft, many bags of Phobos dust are strapped to it. They form almost all the anchor mass of this skyhook. The material is of no mining interest, it is strictly bulk for stabilizing the skyhook.

    Cylinders

    As discussed below in Birth of Worlds, O'Neill cylinders are crucial to development across the worlds of the SITH. At Gagarin and Anshar, the superstructure of cylinders for all the surface skyhooks is fabricated by the end of this phase. The Chukwas take them to their destinations, along with the robot crews that assemble them and then complete the construction of the cylinder colonies.

    The first twin-cylinder colony is built on Magnificent Desolation. Like Gagarin, it gets a cylinder that extends south of the tuning-fork shape of the climber docks. In its case, there is another cylinder just the same that extends to the north. Ships are ferried down the upper tether and berthed above the two cylinders. While they are still under construction, many of those ships arrive bearing Phobos dust for their radiation shields. Slag from Gagarin and Anshar is added to the shielding too.

    These are the family cylinders for colonists that are pregnant or have small children, which is discussed in the Children section. As it will take time to truly establish how to ensure the health of these colonists, these cylinders are made as big as possible. It is taken into consideration that they may be needed for colonists whose health can only be aided by constant full gravity, which may include others besides the very young and the pregnant - as the population of the Moon grows, they may need to support many people. Also, they are further greenhouse spaces, providing a buffer to the food supply.

    They measure 2 km in diameter and 3 km long, each. The whole interior is open below the 200 m closest to the tethers, which is ring after ring of floors, from the outer wall to the hub, each one experiencing slightly less simulated gravity than the one below. Hills created within the cylinders also have buildings under their overlay of soil and plant life. Most of the inner surface has at least two levels of floor space underneath the forest, grasslands, and gardens receiving the sunlight coming in through the expanse of glazing at the far end of each cylinder.

    Crossroads, Sagan, and Babel then all get cylinders like this too. In their case, this is principally for farming, and ecosystem research. Part of their harvests are shipped to Anshar and Hepit, and also to all the other cylinder colonies around other worlds.

    To support upcoming development on all the worlds of the SITH, they are all slated to have O'Neill cylinders incorporated into the anchor masses of their surface skyhooks. Work on this begins at the end of this phase and continues afterwards. Ceres and Psyche are included in this drive. Wherever a continuous human presence is being planned, it is best to have such a colony. There is as much industrial activity in space as there is on the surface of these worlds, except for the Moon and of course Earth. In many places, most industry is in space. Cities that will float in the atmosphere of Venus are prepared at the anchor of the surface skyhook and then deployed into the atmosphere bit by bit. Microbes and fungi native to Mars have been found (we shall suppose), and so while they continue to be studied, heavy industry in their environment is forbidden. Instead, machines and habs for the surface are made in orbit and then delivered by the LNCs, and humans are permitted on the surface only in very specific areas, under very specific conditions. Psyche and Ceres have so little gravity, access to the full gravity in the cylinders is important for complete health. The surface of Titan is too hostile for a human habitat. In all these places, the real action is in orbit, on the skyhooks. People who go to these worlds on business usually stay in the cylinders, and may never go to the surface. The cylinders are welcoming, pleasant places thanks to their scale. The lack of time on the worlds below them is not much sacrifice.

    Children

    We are conjecturing that a full gravity environment is required at all times for the proper health of unborn children, and that toddlers are slowly able to adapt to lunar gravity for ever longer stretches. It is critical for healthy development of growing children that they maintain a vigorous exercise regimen that includes swimming, physical exercise while in centrifuge environments, and lots of jumping, acrobatics, vertical playgrounds, and lunar parkour. As similar activity remains important for adults too, all this activity is heavily integrated into lunar society and its architecture. Children may need supplements or medicines to help regulate their growth and their bodies, perhaps more so at certain stages of development.

    We shall say that children need to sleep in centrifuges under a full gravity, and spend at least an hour a day in them doing some form of exercise. This need is nicely supplied by inflatable centrifuges that are erected and inflated each evening in the courtyards of Lalande City. Each tribe has a courtyard, either on their level of their tower, or in the middle of their collection of houses, if they live in the rim. The interior of these centrifuges is basically a ring-shaped, sideways bouncy castle. The children rarely need any motivation at all to jump around inside them and get up to general shenanigans. In the morning after they wake the centrifuge is stopped, they get out, and it's deflated and stored away until needed again that evening.

    They also need to swim pretty much every day. They are taught how while they are infants. Swimming pools are everywhere in the lunar colonies, including a bunch in each tower. This exercise is important for adults too. Families and often whole tribes share the activity. Vertically oriented playgrounds that are scaled-down versions of the ones adults use are dotted throughout the towers as well.

    Based on the information we have now (which is very little), this is a reasonable guess as to a physical regimen that would keep kids healthy. The radiation environment in the colonies is as low as on Earth by the time children are present, in that regard there is no concern. However, they would not be allowed to venture outside (in the cab of a surface rover or in a shuttle) unless we know they can tolerate those brief exposures to elevated radiation. Children would be transported to Lalande City from Maggie's cylinders in mother ships once they are old enough, and would not leave until they reach the age research has shown is safe for such things.

    The first children appear in the colony in the last two years of this phase. Their parents return with them from Earth when they have reached the age of five. Extensive animals studies in primates and higher mammals such as dogs and cats show this age to be adequate for safety. Initial evaluations are done at Anshar station over a few months to check that everything is in order. The children seem to be able to adapt fine, perhaps after some adjustments are made as to physical routines, diet, and supplements. The families continue on to Cernan's Promise once the medical staff judge the children will be safe if they follow the regimen.

    The children are greeted by the tribes with glee. There are only about a hundred in the colony at the end of this phase, when Lalande City opens. Their tribes share the task of raising them, largely because their 'uncles' and 'aunts' insist. There are no tribes that have more than one child, and most have none. Wherever the children go, they are carefully watched over by everyone around them. They thus become really quite confident and trusting.

    At the end of this phase, hundreds more families are shortly expected to arrive with children of their own. Pregnant couples are now staying on Magnificent Desolation, near to home and in close contact with their tribe. The tribes are eager to have children in their ranks, and so most of them reorganize so they are smaller, and have space for a few couples planning to have children.

    Tribal Life

    Everything is centered around tribes on the Moon. They ensure humanity in a place that is heavily robotized, automated, and computerized. They provide social cohesion in a place composed of a mish-mash of every culture on Earth, while allowing enough autonomy to preserve different ways of life. They prevent authority from becoming concentrated in a place where all the needs of life can only be provided by using a ton of complex technology, which could easily be abused if control was in the hands of few people. From the beginning, tribal organization was fostered in order to keep people looking out for each other and holding together in a dangerous, alien place. Once it seeps into the fundamental fabric of lunar society, it is enshrined as the central pillar of everything.

    Each year or each month, tribes receive an allotment of robots, food and cargo mass, even a little transit capacity to other colonies and the skyhooks. They use it as they decide among themselves. This is strong incentive for them to learn to make plans as a group, and wrestle through tough decisions. As individuals aren't entitled to any free supplies themselves, and some of these things are expensive to buy (like cargo mass and seats on shuttles), if they can't work with their tribe to get what they want, they aren't going to get it.

    Tribes are perfectly free to use their allotments for business. Successful tribes figure out what skills they have and use them together to make a little money. Or a lot of money. Their tribal space is one of the resources that can be important in this - each tribe has a compound that can accommodate a small business or two if cleverly used. How earnings are shared within the tribe is up to them.

    There is a catch to this, one a healthy tribe doesn't even notice, and an unhealthy tribe is keenly aware of. Tribe is for life. They can't expel a member. Even if a member commits a serious crime, one for which there is a penalty of confinement - the confinement is with the tribe. It's a form of house arrest, which their own tribe must monitor.

    This can cause resentment, but people rarely criticize the system in general. It's better than any alternative that anyone has. That same tribal responsibility also means that people who are aged and need constant care are cared for by their tribe, as are people who have a serious chronic illness. It's a social guarantee. It makes people feel very secure and fosters a sense of social responsibility. Thanks to that guarantee, and the essential guarantee on top of it, tribes vote according to their conscience, not according to any fear they have for the future. This is important to the effective leadership of the colonies.

    Once it is time for the colonies to decide how to run the Moon Agency, tribes elect the Moon Agency Director and the Moon Agency Council, who then make decisions during their terms. Each tribe gets one vote. They may decide how they determine their vote - simple majority, consensus, secret ballot, show of hands, whatever Jane says - then it is publicly cast on behalf of the whole tribe. It is like having a huge number of very small constituencies. The dynamics this creates mean that votes are normally considered much more skillfully and thoroughly than voting in other democracies.

    Many measures are taken to keep tribes strong, and create new tribes that are strong. The maximum number of people a tribe may have is 50, and the minimum is 40 - a pretty narrow range. Long-standing tribes are permitted to 'adopt' people to maintain balance and variety in their numbers. There must be enough young people to easily look after old people, for instance. Children provide vitality and all tribes want to have a few around. When people marry one partner moves to the tribe of the other partner.

    People up for 'adoption' come from tribes with too many people. Those people must choose freely to switch tribes - expulsion isn't allowed under any circumstances. Sometimes a new tribe is made out of handfuls of people from several tribes that have gotten too big.

    The private citizens that come in the last rounds of the Residence Program train with a group of people before they come, just like residents always have, and that group becomes their tribe. That's a requirement. The ISA and the MA have become highly skilled at matching people to create good tribes. That skill grows out of the skill space agencies today already have, in putting together teams and training them to act together effectively even under high stress. The training they go through is more about forming social bonds and becoming a team than anything else.

    After the Residence Program ends, and immigration begins, the tribe system is maintained by holding those training programs on the Moon itself. Colonists help arriving immigrants organize themselves into groups, and impose a few basic requirements on the makeup of groups. There must be a range of ages and a gender balance, for instance.

    If a tribe is really in trouble, it can be disbanded. The members must be picked up by other tribes. Possible reasons could be something like having too many elderly members. This happens with a few of the original tribes, who got complacent and didn't renew themselves enough with young members. A tribe may request disbandment, or it may be imposed on them. When requested, it is not granted lightly. The tribe must go through a long process and in the end the request may be denied.

    Tribes receive an incentive package to encourage them to adopt 'strays' without tribe due to disbandment. They are probably going to be a lot of work or difficult to integrate into their group, so incentives are needed. Disbandment is pretty rare, though. Strays start to be a minor phenomenon when immigration begins. Some arriving immigrants want to be part of existing tribes and seek to get adopted by one. Ones with children or planning to have children have no trouble swinging such a deal. The MA doesn't offer incentives in such cases. If an immigrant can't convince a tribe to take them, they usually get placed in a new tribe like most immigrants. Sometimes the MA decides to offer an incentive package for a mature tribe to take them, if they see trouble ahead with them.

    The Economy

    Businesses and projects the Moon participates in now provide a large chunk of Earth's electrical power, and most of its communications, surveillance, and observations of all kinds, from weather to traffic. All of these markets are large and highly profitable.

    Many of humanity's most talented roboticists now live on the Moon or work closely with Moon projects. The Moon is robotics heaven. The robotics knowledge acquired through lunar development is open source, but the Moon still makes a lot of money on it. The Moon exports high-end robots to businesses doing manufacturing in Earth orbit. Moon residents form their own companies doing the same thing. Now that Anshar is complete, manufactured goods from orbit are far more competitive, so that is a huge market. The Moon both provides most of the robots working on Anshar, and thanks to the price drop for delivery to Earth Anshar provides, now sells a lot of robots to companies on Earth itself.

    Software for robots, and software in general, remains a gigantic market. Programming of advanced robots is a very carefully regulated business in which lunar colonists form a large percentage of the top people. They are paid extremely well for these services when contracted, and launch a number of companies specializing in it.

    The Moon Agency and the Moon Fund have a slice of almost everything happening in space. New enterprises seeking to enter the field are wise to play ball with them and the ISA. The more people move into space, and the more infrastructure on other worlds develops, the more this snowballs.

    The Moon is crammed with very wealthy people who hold as central values that all people deserve the basics of life and it's best for everyone to ensure everyone has them. They believe in a close-knit society which also accommodates a wide range of cultures and lifestyles. They are, both individually and collectively, highly influential. The Moon is now a seat of power.

    The Birth of Worlds

    As this timeline closes, the slope of the curve is only getting steeper. With skyhooks tossing great ships back and forth and robots swarming outwards, bent on building vast and magical things all across the solar system, humanity's sense of identity has not simply been shifted. It's been challenged.

    To appreciate the nature of Moonwards, one must understand that all these things will come to pass before the turn of the century. The details will be different, but the scope will be just like this. It is likely that the 50 year timeline shown here is about the time we have before this is the solar system we live in. Once we pass certain thresholds, the scale of our undertakings will explode in size so dramatically, it falls to us now to carefully contemplate what it really means to be human. That task must be well underway, and a consensus gelling, before we hold the power in our hands that this future will bestow upon us.

    The technical skills this timeline assumes we acquire are a reasonable guess, if anything on the conservative side. The question is what we will do with those skills. So let us consider exactly how vast this future is, in this vision where our focus is on growth of this kind. At the opening of this phase, new worlds are being born across the solar system.

    The Moon has everything it needs to become home to millions of people. A number of critical things must be imported, but the Moon easily has the cash for that. Besides, it's largely the Moon that is building the infrastructure to get those imports in bulk, and that benefits everyone, in ways we won't even see until we have such infrastructure. The Skyhook Interplanetary Transport Hubs are an extraordinary achievement, the Autobahn system of space.

    It gets water and ammonia from Callisto; water, graphite, and a mix of salts from Ceres; nitrogen and methane from Titan; carbon dioxide, nitrogen and argon from Venus and Mars. Supplementing the rare metals that come from asteroid mining near the Moon are metal shipments from Mercury and Psyche. A few important chemicals still come from Earth - boron, iodine, fluorine. That's everything it must have in great quantity to build a civilization. It takes a lot of ships to bring in the amounts needed for the rapid development of new surface cities, cylinder colonies, and all its manufacturing. Like a highway system, it is only with a high level of traffic that the skyhooks shine as a cheap and versatile means of transport. Hundreds of Toss ships are plying those routes by the end of Phase 4. In a few years, there are thousands, and they have gotten even larger. All of these materials and more are being traded across the solar system, enabling every world in the SITH to also be home to millions.

    The Moonwards logo, of cities sparkling at night across the face of the Moon, is a real thing in only a few more decades in this reality, with its focus on such growth. Giant bubble cities of a million people float in the skies of Venus. With the question of ensuring a habitat for native life resolved, cities start to sprout across Mars, starting from the vast caldera of Arsia Mons. Vast ice castles are built on Ceres and Callisto. A city grows in Tolkien Crater at Mercury's north pole. All the surface skyhooks sprout cylinder colonies, several of those grow quickly.

    On Earth, power now mostly comes from space. Electrical power... and power in general. The backbone of this world's communications, data services, and electrical systems reside in space. Key manufacturing industries are mostly in space too. Microchips, CNT cable and graphene are plausible cases of this, there will surely be others we can't anticipate. A place that controls all of these things has tremendous economic and political power.

    It also has unassailable military power, so much so, that in order to realize this future, it is imperative that Earth unify sufficiently that war between nations is no longer imaginable. Only a century ago, Europe rushed blindly into the greatest war humanity had ever known (at the time). Today war between Europe's great powers is unimaginable. This is a great achievement. All we need to do is repeat it, in the next thirty years. Preferably, without learning how by enduring the suffering of another world war.

    We must also maintain good bonds with all our lunar colonies. A Moon with an actual city on it like Lalande and skyhooks like Gagarin and Magnificent Desolation would be a formidable enemy. The Moon's capacity to launch missiles is vastly superior because of its low gravity and lack of an atmosphere. The radiation shielding around every inhabited space is also impact shielding - heavy fortification comes included in the package. The Moon need not fear radiation from nuclear weapons, it's already built to block high radiation and it has no water or air that radioactive particles can spread through.

    For the perfect super-villain storyline, a war-like lunar culture could choose not to target Earth directly. Instead, it could go after its sunlight. With its capacity to launch in bulk, it could send enough simple solar sails to the Earth Sun L1 point to block out some 5% or so of Earth's sunlight, sending the planet into permanent winter. The deliciously evil thing about this is that it would be like having a dimmer switch on planet Earth. The orbits of the sails could be dilated or constricted in a few days to let all the sun in, or adjust how much is being blocked.

    That dark future could be executed by other planets as well. It's best just to avoid the whole idea by ensuring we don't fall to such demented depths. We probably would never do such a thing to each other anyhow. We aren't so bad. We're just immature.

    The point here really is that this is how much power is coming our way. That same plan when applied to Venus isn't evil at all, it's a great first step to making the surface accessible, and creating a better environment for the floating cities. A plan to block a large fraction of the sunlight from reaching Venus would allow it to slowly cool. The scale of such a project would take a few decades to complete, and then the results would not be very noticeable for a few decades more. But it would be an actual initial step towards an era of terraforming, one we would be completely capable of.

    We are going to have the power to change the face of planets, and we will. It is foolish to turn away from that as though we can make it not happen by forbidding it. It's even more foolish, and rather sad, to think we shouldn't. Yes, we will very probably make mistakes that do a lot of damage, but we'll learn from that and do better. Only if we exercise the power we have will we grow, only by owning up to our true natures will we learn to repair the damage we've done to our own planet in our innocent youth.

    Our sense of identity is about to be challenged, and we will respond by reorganizing ourselves around a new central project. That is what humanity has always done in the past at such moments. That central project will allow us to define ourselves in a way that gives us a sense of purpose, one so clear and strong we can all unify around it and set aside all differences of real consequence. Upon contemplating our past, and our present, and our dreams, and the powers we are pursuing, what that central project is seems clear.

    Increase Life.