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Far out proposal

(Note: the following is one of various posts that were copied here from the Moonwards.com forum for the sake of preserving the early days of the project. It was originally posted there on Feb 9th, 2016.)


From Sigvart Brendberg:

Two layers of reflective aluminium foil around the 18x18x18 meter Thermal Energy STorage cube (TESTcube?) is 3900 m².

What if this foil was used for something else?

Say you have all of it in one sheet at approximately the EML1 point. (not exactly as we must compensate for radiation pressure).

That is a 4.9 MW flash light!

It would of course be tilted 45 degrees at dusk and dawn, so that reduce the power to 3.5 MW, and also, pointing the beam directly at the base is a challenge. Was 300W/m² what the plants needed? Well, then it is enough for a 12000 m² garden.

I know Moonwards is not intended to be a sci-fi setting, and the main focus is keeping things as realistic as possible, but I just had to say it.

My reply: 

<blockquote>Hey, if it works technically, it deserves to be examined and depicted on the site. I have heard a bit about such ideas, but never looked for articles about it because i had the idea it would be for farther in the future. Of course i hope that Moonwards will grow into a 3d world depicting a variety of lunar bases at various points in the future. It’s just that i began with a point and a set of installations that seemed like they should be done first, based on my limited knowledge. </blockquote><blockquote>I was concerned about the aiming, like you mention. I also wondered about how flat the reflectors would need to be to get the majority of the light to fall neatly on the base. If those can be managed, then absolutely it should be modeled and included. Here you have a big advantage over me until i set aside modelling, writing, and coding the website to learn a lot more math and physics. If you can establish what the parameters should be and sketch out a design, i’ll make the model. Or help you make the model if you wish, or something like that. </blockquote><blockquote>There has to be a few papers out there on this concept. I can’t think of how one might search for them. Maybe ask in the Pod Bay, TildalWave might have an idea. A couple of simple searches on NTRS didn’t yield anything. A search for ‘reflector earth moon’ (couldn’t think of better) yielded Russians to Test Space Mirror as Giant Night Light for Earth, from the New York Times, 1993. Surprisingly close for such a simple search, actually. </blockquote><blockquote>There are of course other reasons to create an installation at the EML1 point, so such a system there could be refined and expanded over time. Again, the challenge is to get things going, but if Moonwards catches on and we have the resources, modelling such a station would be a good project. My sense right now is that once Cernan’s Promise is basically set up - it will constantly be expanded, but once all its principal installations have a decent model - then it is time to model a polar base, and an EML1 station. </blockquote><blockquote>Also, in my mission to goad people into taking space more seriously, i of course did the half-baked calculation in this post, in which i mused how much area of mirror would be needed on the Moon to cause chaos on Earth. Perhaps you would like to play with that idea for your EML1 installation too. After all, if we propose mirrors in space big enough to light lunar crops overnight to feed the lunar populace, what might those do if they were turned towards the Earth and focused on a much tighter area? :]]]</blockquote>