Moon's water reserves insufficient to sustain a lunar city, astronomers find:
Some countries and even wealthy individuals are setting their sights on the Moon, with ambitious plans to create a lunar colony.
That would require a lot of resources launched from Earth, but how much water and power would be required to keep a lunar city going?
Astronomers Martin Elvis and Jonathan McDowell from the Smithsonian Astrophysical Observatory have now taken a look at the resources required for several population sizes.
When it comes to power, the pair think it should be possible to generate sufficient energy even for a large city and without the need for nuclear power.
They estimate it would be possible to generate 3 GW of electricity using kilometre-tall towers covered with photovoltaic arrays. Not only that but it would be possible to manufacture solar panels on the Moon given the amount of silicon on the surface.
Yet it is not good news when it comes to water consumption. We have known for well over a decade that the Moon's poles contain water ice, possibly as much as a billion tonnes, with Moon-orbiting craft mapping out likely locations in great detail.
Even assuming one billion tonnes of water on the Moon, if nothing was recycled then a city of a million would last only a few years, while a population of 100,000 would run for 20 years before running dry.
Even when recycling the water with an efficiency of 98% – as performed on the International Space Station – a city of a million would only have enough water for around a century.
The authors say that to sustain a lunar city of that size would require improving water-recycling efficiencies beyond 99.5%, reducing water usage through vertical farming or simply finding more water on the Moon.
So for now it sounds like a Moon village may be the only possibility. The authors state that a town of around 10,000 people, for example, may be sustainable for several centuries.
Journal Reference: https://doi.org/10.3389/frspt.2026.1894104
(Score: 3, Interesting) by Undefined on Monday September 28, @12:31PM (5 children)
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(Score: 5, Insightful) by JoeMerchant on Monday September 28, @01:36PM
> fetching comets would be relatively easy. There's plenty of water "out there."
Fetching stuff from "out there" whether to the moon or the Australian Outback is something I think is very worthwhile to practice, not only for the resources gained, but for the practical operational experience of redirecting things in NEO to where we want them to go.
Of course, such capabilities are even more frightening than nuclear weapons...
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(Score: 2) by vux984 on Monday September 28, @06:44PM (2 children)
What do they even mean if 'nothing was recycled'?
Obviously recycling would be the default, no? Even without explicit recyling, where would the water go? Surely nobody would be stupid enough to just dump it on the surface and let it all evaporate into space?? Surely some sort of "water cycle" on the moon is all but inevitable. Even in the worst case, you'd think all the sewage and industrial outflow would be dumped in an underground cave or cistern somewhere and frozen, so that when they ran out of "clean ice" they could start reprocessing the dirty ice, instead of saying ..."oops".
Also, you say "Fetching comets would be relatively easy" relative to what exactly? Comets are not "easy" to fetch. And if they were relatively easy to fetch, in addition to a lunar water supply, you'd also have a new superweapon with which to threaten human extinction with. I'm not sure we actually want them to be easy to fetch yet.
(Score: 2, Interesting) by Undefined on Tuesday September 29, @11:00AM (1 child)
Because the Earth's gravity is near the threshold of what a chemical rocket can do to get off with any significant load, and may be beyond the threshold of constructing a space elevator, getting anything going above LEO is very, very difficult. That includes missions to the outer planets and beyond.
From the moon, however, the difficulty due to gravity is much lower. Getting off the moon is much easier, and therefore establishing space-based industry is much easier once the initial (very) difficult push kickstarts the process. It follows that carrying a load then also becomes much – relative to the Earth – easier. Working from space instead of the moon can be easier yet. There are multiple thruster technologies that can serve.
Comets consist of, among other things, water and methane. Once they are brought in (or even while "out there" with robotics) they can be used not only as source of water but also as sources of fuel. Asteroids can serve as sources of other raw materials. They are also easier to get to, so there's that.
It's a matter of getting the cycle going, more than anything else. We're getting closer to self-repairing and self-maintaining robotics. That will be a huge asset for this sort of thing.
We also really need to develop the ability to redirect largish masses if we want to survive as a technological species. Or at all.
Superweapons are easy and already here. That horse is so far out of the barn that the barn doesn't even smell like horse any longer.
I find myself unconvinced any space-capable nation would need to go to the trouble of fetching a large mass to toss, along with dealing with another such nation re-directing the mass (the former capability means the latter is also just as easy), when biologicals. atomics (explosives, EMP, radiation, poisons, etc.), toxins such as anthrax, etc., are much easier to create and deliver. In the final analysis, getting off the earth could address the "all our eggs in one basket" problem as well once things really get going.
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(Score: 3, Insightful) by vux984 on Tuesday September 29, @07:27PM
Ok, so you mean relatively easy to fetching it from/to earth. Sure. I guess. But its still insanely hard. Getting a mission to 'dock' with a comet is plausible but not remotely easy; and is likely a multi-decade mission given where even the closest comets hang out. The closet we've done is Stardust which just flew a probe through a comet's coma and scooped up some particles.
Delivering and attaching some sort of thruster system and fuel to the comet to divert it where ever we want is still comfortably in the realm of science fiction.
We haven't even reliably solved the "i need this to go pretty much anywhere but here" problem (that is: we can't even reliably divert something that's going to hit the earth). And that is a much much simpler problem to solve than "go specifically over there, and end up moving at this angle, rotation, and velocity" so we can then catch it and harvest it.
(Score: 2) by FunkyLich on Tuesday September 29, @06:15AM
1. Humans have so far demonstrated to be very very stupid, especially when it comes to preserve their own habitat. Everything bigger than "my home and my yard" is treated with "fuck that!"
2. I don't think that fetching comets is easy at all. A huge rock that travels at roughly 130000km/h doesn't care where you're located when you want to fetch it.
3. Asteroid mining is easy is Eve Online and The Expanse. But it really is a lot trickier than that
4. Indeed, a moon city is mostly stuff for science fiction. Industry is utterly out of the question, there are simply not enough resources there to support the complex industrial scale operations. For scientific research, half a village is more than enough.
5. Absolutely.
(Score: 2) by BananaPhone on Monday September 28, @05:40PM (1 child)
water via asteroids? duh
(Score: 1) by Undefined on Tuesday September 29, @11:02AM
Water via comets. It's a given.
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(Score: 1, Insightful) by Anonymous Coward on Monday September 28, @06:40PM
Watch The Shining
No matter how much or how little water you have, you will go nuts before you run out.
The only "colonies" we'll be putting on the moon are prison colonies.
(Score: 3, Touché) by anotherblackhat on Monday September 28, @09:09PM (1 child)
Without recycling, water on the Earth would run out pretty quick too.
We use a ridiculous amount of water in the US (~100 gallons per household per day) but that's only because water is ridiculously plentiful and ridiculously cheap.
Despite what The Expanse might claim, water isn't destroyed when it's used, it just gets dirty.
Since the mean temperature on the moon is well below 0° (-23° IIRC) you can purify water via fractional freezing easy enough.
By alternating boiling (direct sunlight) and freezing (shade) 99.999% recycling ought to be possible, and compared to the problem of keeping the air, holding on to the water should relatively easy.
Gah. What did they think Lunar colonists would do, open air farming?
There's plenty of space available, there's no need (or advantage) to stacking the plants vertically.
And there's a big advantage to making the greenhouses accessible to the colonists as parks, even if it does reduce crop yields slightly.
(Score: 4, Insightful) by bussdriver on Monday September 28, @09:55PM
I keep wondering why serious people talk about anything above the ground. a tiny screw of space junk crashing into your structure at 20,000 miles per hour is going to do more than put a chip in the window.. not to mention anything floating in space that is not moving along our orbit.
(Score: 2) by VLM on Wednesday September 30, @01:46PM
The best "Ore" for mining water would be dirt from around the city if its leaky, so I suspect recycling rates far beyond 99% will be the norm.
It's like how on earth once you can refine magnesium and uranium from seawater you're pretty much set for life, well until you fission all the uranium LOL. In a likewise manner, once you've got the tech to deploy solar powered moisture miners, when they work well enough at a low enough concentration to just sit anywhere, like a dehumidifier on earth but more crazy.
My guess is carried to an extreme they'll be using infinite electricity to turn oxygen containing compound rocks into oxygen gas, and capture solar wind from the sun and mix them together in a controlled fashion. According to google there's a NASA page along the lines of one of the lunar landing apollo mission sample rocks was 45% oxygen by weight, and as long as the sun shines you'll have infinite "free" low concentration hydrogen, so the moon, with some industrial help, has near enough infinite water.