Power on the moon: What will it take to survive the lunar night?
universetoday.com
universetoday.com
Or somewhat sexier, beamed orbital power or mirrors are less technically challenging than on earth.
Either should be less expensive than hauling nuclear reactors from earth and ensuring they get reliable cooling.
Ideally you keep as much equipment as close to an even temperature as you can, or it might never turn on again when daylight comes.
[1]: the exact definition varies, but it's in that general area. Industrial is -40°C and commercial is 0.
Some stations in Antarctica were built that way only during summers, in winters they were left empty till finished and operational.
It's so commonplace yet absurd/impressive when you really think about it.
I feel like this just creates the new problems of operating, powering, and maintaining the robots, plus all the difficulties associated with mining asteroids and refining the mined materials somewhere (presumably somewhere that's not Earth's surface, which means we still need to generate power somewhere off Earth for this to work).
Even with nuclear, it can be far safer: small reactors need less containment. There is no risk of fallout without an atmosphere, and no ground water to contaminate.
Still, relying too much on it and failing (melting down) will put in danger the whole human space program. For low-power unmanned applications the RTG remains unbeatable.
Essentially, flying nuclear material is treated with the same level of basic care as flying humans.
Once the material is in space the regulations aren't as thorough, I imagine the most that NASA considers is for the launch to be into a direct injection orbit or at a sufficiently high parking orbit that there isn't an immediate risk of uncontrolled reentry in case of some failure.
https://space.stackexchange.com/questions/17518/what-does-it...
I'd speculate that it would spontaneously propagate along the lunar surface through electrostatic forces. The fallout particles would be highly charged (self-ionizing), very small, and in a perfect vacuum -- a recipe for some seriously weird dust physics.
You take neutron radiation (well, its consequences), but that is pretty much non-existent when compared to nuclear waste.
The key limitation is going to be transporting stuff from earth. Solar panels have a key advantage here: they are pretty light and easy to deploy. There's no wind or weather that will dust them over. And per launch, you can move some significant amount of power generation.
The absence of atmosphere would make it viable to beam electrical energy down from orbit. Seems cheaper.
Studies have shown that in lunar vacuum, fine dust in the regolith can travel halfway around the globe and even end up in lunar orbit and beyond with just a little kick. https://www.theverge.com/2019/7/17/18663203/apollo-11-annive...
Fallout is mostly irradiated material spread by an explosion, so as long as you have a surface and some amount of debris from an accident that doesn’t reach escape velocity you can have fallout.
At the poles this could enable some permanent power generation by getting the panels high enough to access permanent sunlight.
Solar panels should be able to provide the necessary energy which can be stored in piles of rock and insulation should be able to to prevent the loss.
The 'article' says that the lunar night is rife with problems but doesn't mention what they are. There is no weather after all.
Hydrocarbons will likely be in short supply on the moon but if there is, say, a zinc mined, it could be "burned" in zinc-air cells.
The biggest challenge to the obvious solutions - either solar plus lots of batteries, or nuclear - would be to crack water into oxygen and hydrogen, and then burn them during the night. The challenge there is storing the hydrogen. But if you do that, basically what you'd be doing is using hydrogen/oxygen as an energy storage mechanism, e.g. as a battery. You'd need to use solar during the day to crack the water.
12% by mass is iron, with calcium, aluminum, magnesium at 7-8%. These could be considered ores worth mining on Earth. All four metals readily burn in oxygen, even though aluminum needs some help igniting.
There are various studies to have stuff survive lunar night without a nuclear source, and it takes on the order of 10kg of stuff to keep a 1kg payload alive. And in turn that takes 100kg of spacecraft/fuel to fly it all there. That’s not including the rocket and its fuel to get to Earth orbit first.
You need a pair of very large bags of regolith to store the heat and cold in, and a gas to percolate through them from radiators exposed alternately to sun and black sky.
Or you can just put up very big reflectors in orbit, lighting up your solar panels. Maybe they pump laser tubes pointed at your solar panels.
Nukes would be a big nuisance, needing constant maintenance, unless you just run a naked pile at incandescent temperature and catch the light coming off photovoltaically.
If we had piles of Pu-240 we could use RTGs, though they wouldn't be very efficient considering the amount of mass we'd have to send.
Running a naked reactor doesn't sound so bad considering there's no atmosphere or water sources to poison -- just stay away from the reactor. Running a steam turbine shouldn't be too hard, but it probably can't be serviced -- if it breaks, you replace it.
Just remember: nuke first, then colonize. So, sooner rather than later.
Would heat pumps work on the moon?
Where can I book a Starship flight for $1M?
But even at $100m/launch, a big fat copper wire (IIRC aluminium is better per unit mass) would still make more sense than shipping up a nuclear reactor or a huge pile of batteries, and that part of this hypothetical mission would still be about 80% cheaper than the JWST.
Starship is supposed to be cheaper, the moon is definitely more expensive.
I wonder, how hard is it to make aluminium from the oxide if you're bootstrapping and in a vacuum? I know the normal process is "melt it with added cryolites and apply current for electrolysis", but if the goal is low mass rather than good energy efficiency, can you do it a different way? Like, what happens if you focus sunlight and just melt it, does the oxygen bubble out in a vacuum, or is this just going to do vapor deposition of sapphire on all nearby surfaces?
That would bump that number up to ~$10m/$20m or so. Still ridiculously cheap and not likely to be anywhere close to the price charged as it would absolutely sink the rest of the market, which SpaceX is not interested in doing.
If you sent it at 1000V, the I²R losses to send 1000A over that cable outweigh the transmitted power by 600 to 1 and your cable is burning 200kW per kilometre. Which in a vacuum would probably just melt it in fairly short order.
Which is why the bigger HVDC links get, the higher the voltage: there's a 1MV+ system in China that sends 12GW over 3000km.
Also I'm not sure how lunar regolith will work with regards to the "earth" return path so you might well actually need two wires.
One can see pretty quickly that any larger constructions far from earth would really benefit from maximum use of local materials.
Now, you could lay both conductors in parallel and only need to build the power line half-way around the moon, probably save some dough on prospecting for and constructing pylon sites that way. Alternatively, you could run a single conductor all the way around. Doing that, you could establish a lunar scale magnetic field, though it'd probably be pretty wimpy unless you ran serious kA (MA?) of current, which would mean much bigger conductors etc, but it's fun to think about. Heck, with a loop that big, you'd probably get significant induction from the solar magnetic field .. which might be something to harness, or might just be a headache for your line operators.
Or a stator in orbit? But hrm… for Mars the same idea needs only 1T to 1.5T stator but has to place xt at lagrange between Mars and Sun. So, I naively guess for the stator to be far enough away that the deflected solar wind merges after the moon could /reall/ mean that the stator would be at lagrange between Earth and Sun, which could have perhaps interesting effects on Earth.
Getting a can to the lunar surface takes launching a bunch of fuel runs, so that much several times over, say $1000+/kg all told.
Bringing cans back from the moon would be counterproductive, except as needed to bring crew home. Maybe you unmount used vacuum engines, cut their bells off, and bring home the fiddly bits. Somebody should find a use for the cast-off cans, eventually, and the cut-off bells. Maybe swing the cans on the ends of a wire for artificial gravity so your bones don't dissolve; though getting in and out would be tricky. You could store energy in their kinetic motion, resolving the nighttime power problem at the expense of variable artificial gravity inside.
Downside to aerogel? It makes for a lousy micro-meteoroid and radiation blocker, unlike something like rockwool that masses more.
To the extent the lunar atmosphere is dense enough to cause meaningful conductive loss, one could pump a better vacuum inside the insulation. The pressure difference between this high vacuum and the lunar atmosphere would be low, so the mechanical strength needed for whatever container holds it would be corresponding low. (This seems very unlikely to be a problem at all. The moon’s atmosphere has an extremely low pressure. Offgassing from the insulation seems like a bigger concern.
It's just weird to me that they wouldn't go to the interesting and water/gas rich craters perpetually at the terminator. You've always got power there... just start digging.
L1 would be easier, but that's still 58 megametres from the moon. Possible, of course, but I'd be surprised if that was really better than a big wire on the lunar surface.
(cue Everybody Wants To Rule the World)