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Sunday, February 23, 2020

Life on the Moon

SpaceX’s vision for a human outpost on the Moon.
I read Artemis a couple of weeks ago and it got me started thinking about long term living on the moon. If we are going to have a base there, we are going to need a regular rocket-to-the-moon service, at least monthly, preferably weekly. I mean ol' Elon's getting pretty good at puttin' rockets up, and since he reuses them the only cost is fuel, which is just natural gas, which is dirt cheap, and oxygen, which he takes out of the air, so it's free. Once they get this regular service going, the cost of going to the moon is going to be too cheap to meter (as they once promised us about nuclear power). Okay, it ain't gonna be cheap, but we should be able to afford it.

Anyone, if we can get that far, we are going to have people living on the moon for days going on weeks, and given what happens to a body hanging out in the International Space Station for a long time (it's bad), we can probably expect similar effects on the moon. One way to compensate would be to build a centrifuge. I proposed building a train that would travel in a circular tunnel at high speed.  The long radius would reduce the difference in force between the head and feet and so should be similar enough to the Earth's gravitational field that there would be no ill effects.

Graviton Carnival Ride
But that would be a major engineering project. Even if you could deliver a tunnel digging machine to the moon, it would likely take ten years finish digging the tunnel. We aren't going to want to wait ten years before we start sending people to the moon, so we need something a little smaller. You can generate enough force to simulate gravity with a small cylinder, you just have to spin it faster. However, if you are standing, there is going to be a large difference in force between your head and feet. However, if you are lying down, the difference in force between the tip of you nose and the back of your head, or the tip of your big toe and your heel, is going to be minimal. It might not be very good for working, but it would be just fine for sleeping. And spending eight hours a night in a full G environment might be enough to keep you healthy enough to return to Earth without suffering the ill effects of 'gravity sickness'.

The city of Philadelphia could easily fit inside a theoretical lunar lava tube. (Image credit: David Blair/Purdue University)
So we take an empty fuel tank, locate an empty lava tube, drag the tank down underground into the lava tube, mount the tank on a couple of big bearings, fill it with air and beds and you've got your one Gee bunkhouse. Shoot, big as those lava tubes are, you could take the whole front end of SpaceX's Starship down there. It would already have everything you need: air, power, water, waste management (yes, we got Dons even on the moon), an airlock and beds.

(The whole point of going underground is to reduce the effect of radiation which is pervasive outside of the Earth's magnetic field. Domes on the surface can be covered with dirt, but a spinning cylinder is going to need some kind of structure to protect it. If a natural cave could be located, that would be perfect.)

Problem with caves on the moon is that they are devoid of air. And even if you could find one that could be sealed (perhaps by coating the interior with some kind of polyurethane), depending on moon rocks for the air you breath (don't you dare move, you rocks you) might not be prudent. Better to have a self contained air-supply, and that means air locks.

Moon Man exits the Quest airlock at the start of U.S. EVA-51. Photo Credit: Oleg Artemyev / Roscosmos
This centrifuge isn't the only thing going to need airlocks. Space ships are going to need them, regular moon domes are going to need them. Airlocks are basically a box with two doors. Domes connected with pressurized corridors won't necessarily need airlocks, but they will need pressure doors in case somebody springs a leak. I look forward to seeing what kind of doors they are going to use for moon houses.


Ole Phat Stu said...

A major problem is going to be the regolith.
The dust is so sharp and it will creep everywhere,
stopping seals from sealing, jamming connectors etc.
It will be a major problem for longer stays on the moon.

Chuck Pergiel said...

That might be another good reason for going underground. If the dust is debris from meteor impacts, underground spaces might be relatively free of dust.