The Machines that make it Possible

Even to reach space we need incredibly complex machines. To live there we will need machines that can do any physical task we can, see as well or better, that anticipate, compensate, and make judgement calls. Recent advancements in robotics stand beside reusable rockets as new factors accelerating our advance into space. The Moon’s harsh surface is no place for a human to work. Spacesuits make you very clumsy, and a ton of infrastructure is needed to keep you alive and safe. Bring on the robots.

Rovers and Robots - the Workhorses

In this project, the approach is taken that the first missions to settle the Moon will focus on developing the robotic infrastructure needed to do construction entirely without humans present. Such robots do not yet exist, but the field is advancing quickly. Development of that technology has a wealth of applications here on Earth, it would make sense to make such R&D a central part of a settlement space program.

The first few missions to the surface work like rover missions today, except with many robots being operated from Earth instead of just one, and performing tasks as much to test their ability to manipulate their environment as to explore and study. Once a human crew is in orbit at Crossroads Station, which is the beginning of the first lunar skyhook, they do a mission to the surface to install equipment that allows the robots to do more demanding and precise work, perform repairs, and install a repair station they can run from Crossroads. The Crossroads crew takes over a large chunk of the remote operations, as the signal delay between them and the robots is imperceptible. After that, the robots build the first permanent habitat and its infrastructure without anyone on-site. (There could be more missions from Crossroads to the surface, but only if there are failures that make it necessary.) Once that hab is near completion, again a crew arrives. They test everything, maybe make some minor final touches. Then they stay. After that the human population ramps up quickly and they operate the robotic machinery from within the habs.

So, great things come from great robots. Rovers and probes in space have already been designed to handle some of the things in the list below, others are new territory:

  • The high radiation environment, which requires special design of computer components. This technology is well developed, but does add cost and increases the bulk of components.
  • On the Peaks of Eternal Light where the first missions are, the temperature change between day and night is not the concern. Instead, it is simply that the sun is very hot and the shade is very cold. Where the ice is, it is very, very cold. Ice mining equipment needs heaters and to be made of specialized materials. Other equipment can be protected with translucent shades that dilute the sunlight, the use of stone, which holds in heat, and some lighting, so it isn't difficult to see in the stark shadows. Away from the poles, where the day and the night are each two weeks long, the same techniques work when done on a larger scale.
  • The extremely abrasive, finely powdered soil that will grind away at any moving part it gets into. And it comes with static cling. Moving parts like joints can be wrapped to minimize the dust that enters, possibly with multiple layers of material. Magnetic brushes seem quite effective for dusting things off, though they haven't been tested on-site. Ultimately, the best thing is to fuse the surface soil into a solid cap of stone wherever robots work (or people).
  • The 3 second round-trip radio transmission delay between Earth and Moon. This is eliminated once there are enough people in orbit, and later at the base, to operate the robots locally. Before that, operation has to consider this factor. So the more the robots can do without needing specific instructions, the better. If a robot is tipping over, it needs regain its balance itself. It needs to be able to handle simple, repetitive tasks on its own. It needs protocols for collision avoidance. It needs to understand what it is looking at well enough to direct itself as it moves around and manipulates things. The video in the sidebar on Boston Dynamics shows how close to this we already are.
  • Extending the point above, the need to be independent. It's doubtful it will ever make sense to have people work out in the open instead of robots. People should be outside only fairly briefly and rather infrequently, to limit their radiation exposure. People hampered by space suits are very clumsy and have trouble sensing their environment. Robots need to be able to do ever more things without human oversight.

It is hard to overstate how much of a difference robots with these capabilities make. They are absolutely necessary for success.

Construction and Fabrication - the Road to Big Business

If there was a way to build a habitable shelter on the Moon that wasn't super hard, we'd already be there. It is important not to underestimate how hard it is to do this. But, the needed technology is coming together and turns out to change the equation of what the best method is.

Most designs for lunar construction up to now have focused on batch processes that don't require much finesse (such as making lunar concrete blocks). Few designs have contemplated use of in situ materials, though, because of the difficulty of delivering the machinery to work them, and the probability such machinery wouldn't last long in such a harsh environment. Almost all serious designs send finished modules built on Earth.

If you plan to stay, you have to be able to build there. If you can build there, you have something you can sell. If you are good at it, you can build for space, too, and that's our whole idea.

All construction designs here are centered around the use of melted regolith to build most things. The basalt found in the lunar maria is especially useful. When basalt is drawn into fibers it has good tension strength. A material that is strong in tension is the key to space construction. Holding in an atmosphere requires it. Basalt rope and cloth can be made with no additives other than a thin application of a sizing chemical to the surface of the threads. This makes construction with basalt much easier.

Some highlands materials spun into glass fibers will also have good tension strength, the question is how much they need to be processed before that's true. The first habitat built uses an approach that minimizes the use of tension elements in consideration of that. The membrane for the roof of First Hab is shipped from Earth, and the hab is built in an excavated pit so the walls and floor can contain an atmosphere with compressive strength only. Building in excavated pits is the technique for the first decades of development for this reason, and also for the radiation protection and thermal regulation provided. For Long Hab, the second habitat, either cables of basalt fiber will be spun using feedstock brought by the shuttles from the maria, or the more extensive infrastructure at that point can be used to create glass fiber from local material that is adequate. At worst, cables can be delivered from Earth.

Quite possibly the different chemistry and environment of the Moon means that glass fibers made there would have much better strength, even without the use of a supporting matrix to reinforce them, as is used with fiberglass on Earth. A paper by James Blacic in Lunar Bases and Space Activities of the 21st Century explores this. Because there is virtually no water in the lunar environment (aside from the special case of the permanently shaded craters of the poles), glass made there will be free of the microscopic defects that are always in glass on Earth because water is everywhere here [?].

"...in the hard vacuum of space, silicates derived from the Moon will not, if we can avoid contaminating them, exhibit the water-induced weakening that is so ubiquitous on Earth. In other words, lunar silicates may possess very high strengths due to an "anhydrous strengthening" effect relative to our common experience on Earth. This possibility has numerous implications for space industrialization"

The issue would be obtaining a feedstock high enough in silica to take advantage of this. The method proposed in the Solar Thermal Furnace section, of separating pyroxene from bulk regolith by melting it and spinning it in a centrifuge at the right temperature, might resolve this issue if combined with a second step. The pyroxene can be melted again, and if spun at a somewhat higher temperature, the olivine will separate from the rest. Then the liquid poured off would be almost all a mixture of silicon, oxygen, and calcium. In that case, the proportion of calcium should be low enough for the glass to be dominated by bonds between oxygen and silicon, which are much stronger. With the additional strength the material would have due to having virtually no hydrogen bonds mixed into its crystal structure (from water contamination), this material may make good cable.

All these designs absolutely depend on the use of agile robots. They don't have to be carpenters, but they do need the manual skills of your typical 5 year old. Guided by human operators, that would be enough.

If you have those robots, what follows is the best way to build. It is far less energy intensive, and far more adaptable, than anything else I've seen. The most energy intensive processes can all be done by concentrating the strong constant sunlight, which is easily done with lenses alone. The equipment needed to start is far less, and less complex. Except for the robots, of course, which are so broadly useful they are still quite mass-efficient, even if they need a bunch of modular drop-in replacement parts shipped with them.

Interactive 3d models

Click the play arrow to load the 3d models below. Check out the controls at the bottom of the model window - especially the bar to click through the annotations, and the double arrows in the corner to make it full screen.

These models are in development, both in what is in them, and in how it is presented. They go through spurts of changes, which should become more frequent and dramatic with time. Right now they are at a pretty early stage.
The production of basalt fiber is critical technology for large construction. Cable can perhaps be imported for the first hab, after that this has to be made to work.
The Melt-In-Place stations need to be the backbone of early construction. They can produce a wide range of useful items, a very wide range if the rovers are agile enough to assist. They can produce materials in bulk, so if the materials have some weaknesses, you can simply use more to compensate.
The hangars will be filled up with lots more things. This early draft gives some sense that industrial scales are sought, and the work flow will be complex.
On to Power - Mining - and Transport