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Power on the moon: What will it take to survive the lunar night?
- rini17 4y agoI suspect this will in the end be solved in utmost unsexy, boring and reliable way by solar plus huge NiFe battery and/or hundreds of kilometers of high voltage grid, manufactured by robots from local resources or asteroid mining. 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.
- mjevans 4y agoBootstrapping issue. Probably going to need the initial bots to have RTG based power mostly as a self-heater.
- Panzer04 4y agoWhat’s wrong with operating half the day? I guess it’s space, so it’s worth a lot of effort, but I’d think if they can avoid RTGs and just use solar they would.
- Oxidation 4y agoThe night is 14 days long and is deeply (cryogenically) cold, which is really bad for lots of hardware. Military component ratings are something like -55°C[1]. Lunar night is more like -130°C. 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.
- rini17 4y agoRight, everything except solar panels should be underground, not only because of temperatures but to keep the regolith away too.
- throwaway14356 4y agohumans use to build with mud, sometimes with walls meters thick. Underground or natural caves would be even better. It doesn't get any less sexy. Not sure how it works with such extremes but on earth it takes months of heating or cooling to get through a few meters of soil.
- mumblemumble 4y agoThere's another bootstrapping issue there: how do you get the underground base installed and functional in less than 14 days?
- deleted 4y ago[deleted]
- rini17 4y agoWhy must the build be done all at once in one go? Humans will land at the dawn, leave before dusk, working in 14 day shifts set up the base. This will repeat for several months till the base gets self-sufficient enough. Some stations in Antarctica were built that way only during summers, in winters they were left empty till finished and operational.
- deleted 4y ago[deleted]
- fbdab103 4y agoI would think that the first generation base would be situated at the poles with perpetual (or as close as possible) sunlight.
- TomK32 4y agoHow about two bases? Simply move people and critical experiments to the other base before nightfall.
- Panzer04 4y agoTravelling a few thousand km is probably harder than just running a wire around the moon ;)
- Oxidation 4y agoEspecially when you have to do it every 2 weeks.
- atoav 4y agoBut is it the same amount of fun?
- TomK32 4y agoYou probably want to travel anyways for exploration and mapping.
- funnymony 4y agoDo you? If we assume robots building stuff. Mapping is a task way easier to automate.
- burnished 4y agoLunar cowboys arent gonna be robbing no wire, nosirree, lunar rail is a necessity.
- rad_gruchalski 4y agoWe can’t outrun it forever…
- atoav 4y agoOne base, on stilts, constantly walking with the sun.
- wankle 4y agoNiFe batteries last for decades, I agree that would be the best choice for the battery type.
- yyyk 4y agoOrbital power has the huge advantage that setting it up is essentially independent of the rest of the mission - we can set up most of the work in advance, so that part doesn't count towards a weight limit and we can abort/wait if it doesn't work. Once a secure base using orbital power is set up, then NiFe should be arranged for redundancy.
- at_a_remove 4y agoI think the heat part would best be Feolite, which is mostly sintered iron oxides, but with some other bits added. It has a tremendous volumetric heat capacity, nearing that of water, but you can crank it way past 100 C without worrying about pressure.
- MrDunham 4y agoOne of my all time favorite everyday engineering things I've learned is the absolute bonkers amount of energy needed to boil water (vs nearly any other fluid). It's so commonplace yet absurd/impressive when you really think about it.
- 6177c40f 4y ago> "manufactured by robots from local resources or asteroid mining." 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).
- Mistletoe 4y agoI am still awaiting the future promised me where 3d printers replicate themselves. This is orders of magnitude easier than robots making themselves in outer space, yet we are still waiting and I assume we always will be.
- dvh 4y agoLet's assume 10mm copper wire to the other side of the moon. 3000km long copper wire 10mm in diameter will have 600 ohms resistance. The amount of copper needed is 235 m³, copper at 9t/m³ weighting 2115 tons in total or 21 starship flights costing $21 milion.
- Aspos 4y agoOn poles it would be a few km run to the nearest peak of ethereal sunshine, not 3000km to the other side of the planet. Would heat pumps work on the moon?
- XorNot 4y agoYes, provided they were ground sourced.
- orbital-decay 4y ago>total or 21 starship flights costing $21 milion Where can I book a Starship flight for $1M?
- ben_w 4y agoWhile I think even twice that is more than a bit optimistic, this story was claiming a target price of $2m/launch: https://www.space.com/spacex-starship-flight-passenger-cost-elon-musk.html https://www.space.com/spacex-starship-flight-passenger-cost-... 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.
- skykooler 4y agoAluminum is also probably better because it’s easy to source on the moon - many of the surface rocks are made of aluminum oxides. Copper, on the other hand, would need to be entirely transported from Earth.
- kwhitefoot 4y agoPeople survive Antarctic winters so I can't see that there is a particularly big challenge. There is no atmosphere on the moon so heat loss to the sky is purely radiative whereas in Antarctica you have winds blowing that cool the habitats by conduction. 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.
- GlenTheMachine 4y agoMcMurdo uses diesel generators. Which require oxygen, which is free on earth and very very expensive on the moon
- rini17 4y agoAny permanent habitation should include a smelter to alleviate some of the cost of shipping metals from Earth. From it oxygen or CO2 will be "waste" byproducts, liquefacting and storing them should not be a problem. I can imagine that having large reserve of oxygen will be desired safety feature. 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.
- seastarer 4y agoThe energy cost of extracting oxygen is higher than you'd get from burning it.
- lalaland1125 4y agoYou would extract oxygen during the day and burn it at night
- GlenTheMachine 4y agoThere's also the cost of the diesel fuel (or whatever fuel you burn) to consider. With no native hydrocarbons on the moon, extracting them would be impossible. So they would need to be launched from earth, at many tens of thousands of dollars per kilogram as an ongoing cost. 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.
- iwwr 4y agoNuclear appears to be the only realistic contender. But the mission architecture of Artemis goes around the problem by having only short stays on the lunar surface. 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.
- Stupulous 4y agoWhat does the risk profile look like for launching nuclear fuel through our atmosphere? It seems intuitively concerning, but I don't know much about nuclear.
- dotnet00 4y agoIt isn't too big of an issue, rockets have to meet certain requirements to fly nuclear material. The flight profile is required to be over water, so intact material just gets diluted or sinks. There are some requirements about how the flight termination system works (eg it shouldn't spread payload debris over a large area) and general reliability considerations identical to those for human spaceflight. 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-mean-for-a-launcher-to-be-nuclear-certified https://space.stackexchange.com/questions/17518/what-does-it...
- acidburnNSA 4y agoBasically zero. Unused nuclear fuel is not very radioactive. You can hold it in your hand with a glove. Once you split atoms it becomes more hazardous, but space nuclear doesn't start up until after it's been successfully lifted.
- perihelions 4y ago
- wankle 4y agoWhat about a large reflector dish grabbing sunlight at some distance from the Moon in a geosynchronous orbit, bouncing energy to a receiving station at the new Artemis site?
- ben_w 4y agoLuna-synchronous is a long way from the moon. So far away, in fact, that you're it. 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.
- djha-skin 4y agoPlutonium, duh
- pfdietz 4y ago(snarls at Karen before the Sea Dragon lifts off) (cue Everybody Wants To Rule the World) https://www.youtube.com/watch?v=SRMDcC0QvFQ https://www.youtube.com/watch?v=SRMDcC0QvFQ
- ngoilapites 4y agoMillions of dollars. One per kg of materials needed. The rest is no constraint.
- nine_k 4y agoHasn't it gotten somehow cheaper by now? Will it when the Starship flies?
- moloch-hai 4y agoStarship and Superheavy ("can and kicker") will not realistically cost any less than $20M per launch, plus whatever what you are launching costs to make, stow, and deploy. If it takes 100 tons to orbit, that is $200/kg minimum. 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.
- dotnet00 4y agoNuclear is probably most practical for long term generalization, for now I think the approach all crewed landers have proposed to use is to place panels as high up as they can to maximize sunlight duration. At the poles this could enable some permanent power generation by getting the panels high enough to access permanent sunlight.
- WalterBright 4y agoPut the moonbase at the pole?
- timerol 4y agoPutting the base at the South Pole of the moon is the current plan. But missions will want to go into craters, which will lead them to have to deal with the long nights
- moloch-hai 4y agoThe very large temperature difference between day and night means you can bank heat in the daytime, and cold in the night, and generate power from the difference. 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.
- cryptonector 4y ago> 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.
- wbl 4y agoSealed free piston Stirling engines might be even lower maintenance and can provide a number of kilowatts pretty simply. Couple with a fast reactor or a combined fuel moderator solution alas TRIGA should work.
- 8bitsrule 4y agoI suppose that a nuke could work out better than the PM-3A did for McMurdo back in 1962.
- sfifs 4y agoDump 3 large solar arrays at 120 degrees on the moon. Run a large power cable 11k km around. You have continuous power.
- chiph 4y agoTo make your power go further, we'd want some impressive insulation in our structures. Aerogel comes to mind, but it's low density and fragility means shipping it by rocket from Earth wouldn't work. However it may be possible to make it locally - the moon has lots of aluminum oxide, but we'd have to ship the water & alcohol needed for synthesis. Removing the water and alcohol after the aerogel structure gets created is done with freeze-drying, something that is easy on the moon, and the water + alcohol can probably be recovered for reuse in the next batch. Downside to aerogel? It makes for a lousy micro-meteoroid and radiation blocker, unlike something like rockwool that masses more.
- pfdietz 4y agoOne could make low density glass foam on the moon simply by dissolving some volatile in molten glass, then spraying the melt into vacuum.
- amluto 4y agoThe moon is a near vacuum, so aerogel is the wrong approach. The main form of heat loss is radiative, and the way to reduce radiative loss is with many layers of shiny things. This works like the superinsulation between layers of a Dewar flask. It could be literally a layered structure or a filling of shiny fluffy stuff inside something else. This will dramatically outperform mineral wool or really anything practical on Earth. All this insulation goes on the outside, vacuum side of whatever pressure vessel people live in. 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.
- kurthr 4y agoJust hang your room from a wire (or 3) and wrap the thing in aluminized (or gold) mylar reflector. You've got an almost perfect thermos. Pretty quickly, you'll have to dump waste heat. Now cooling is pretty easy since just need a radiator in shadow. You could run a full on heat pump if you wanted to collect and store power, but this isn't like earth where there's an atmosphere with wind and rain. Or a place where there isn't always a significant solid angle of 3k space to radiate to, most of the sky is always night. 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.
- nuker 4y agoTLDR: they talked about it.
- Nomentatus 4y agoNuke the moon! Right now the topography of the poles necessitates quite tall towers to get into perpetual sunlight; but a bunch of judiciously placed nukes could easily take away most of the shadow-bringers (crater rims) and reduce the tower height necessary to get up into perpetual light to a small fraction of what it would be now. Just remember: nuke first, then colonize. So, sooner rather than later.
- a9h74j 4y agoMr. Teller, any thoughts on how to create canals on Mars?
- euroderf 4y agoWasn't the plan to practice on a canal thru Nicaragua first ?
- defrost 4y agoThey practiced on home soil and irradiated many US citizens [1] while determining that big explosions aren't all that great, these days we use precision blasting patterns for earth breakup and moving [2]. [1] https://en.wikipedia.org/wiki/Sedan_(nuclear_test) https://en.wikipedia.org/wiki/Sedan_(nuclear_test) [2] https://www.youtube.com/watch?v=nSWURwNC8dc https://www.youtube.com/watch?v=nSWURwNC8dc
- mishkovski 4y agoThe sad state of the Web: https://ibb.co/ZzcxBc4 https://ibb.co/ZzcxBc4