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Vast new stores of water reported on the moon

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Re: Vast new stores of water reported on the moon

#171

Post by AlanSE »

whatshisface wrote: post #158
wongarsu wrote: post #145

Earlier quoted context omitted.

Impact sites of larger asteroids are also great targets for mining operations. For example there's some speculation about the gigantic impact crater on the far side of the moon containing a gigantic metal lump below the surface https://en.wikipedia.org/wiki/South_Pole%E2%80%93Aitken_basi... https://www.independent.co.uk/tech/nasa-moon-mass-crater-met...

It's not entirely clear to me why you'd want to find asteroids on the moon rather than finding them in space, where the mass wouldn't hardly have to be lifted.

The problem with asteroids is the population dynamics and time required with these heliocentric orbits. Yes, there are asteroids at a lower Delta-V than the surface of the moon. There might be only a handful that are even worth capturing and mining. If this scaled up, however, you would quickly deplete this population of NEOs.

While the Delta-V might be less, it's not less by MUCH because you spend most of your fuel getting to Earth's escape velocity in the first place. The Delta-V benefit is also balanced against a massive time lag involved in sending a robotic spacecraft to capture and boost it to an orbit where we can better access and refine it. Or you send the refinery to the asteroid for larger asteroids. Problem there - you'll basically have to build a new refinery for each asteroid. Even for larger NEOs at higher Delta-Vs, the mass is not all that much. It's also not clear that microgravity will be any better than 1/6th gravity.

There are very strong arguments for Lunar mining. We're talking about ~1 week for transit time from Earth to there. The moon can build vast Earth-like industry. You get to cherry-pick a wide variety of asteroid material types (except for volatiles) without building a new factory for each. Surface transportation isn't particularly hard. Materials to build solar panels are widely available.

Asteroids will be useful at some point, but only after we can reach the frost line. Otherwise, the asteroids we get will be parched and not offer much beyond what's on the moon, or what we can lift from Earth. After we get to the frost line, we will get vast troves of organic material, but this is at tremendous Delta-V cost and outrageously remote and time consuming to access.

Re: Vast new stores of water reported on the moon

#172

Post by marcosdumay »

alex_young wrote: post #170
credit_guy wrote: post #113

Just to be clear, the "vast stores" of water are only theoretical. There are no implications for Moon colonies. You are not going to try to extract water from glass beads. You would need to go through thousands of tons of regolith before extracting a single liter of water, and that's only if you have 100% efficiency, which you will not have. If we ever decide to have Moon colonies we'll have 3 big problems: we won't…

Seems like the 28 day, uh, day will be a bigger problem. Everything from keeping power on for 14 days without solar to keeping the temperature up to human habitability levels will be challenging won’t it?

It's a different kind of problem. The Moon is a big ball of stuff outside of the Earth's gravity.

If that's stuff is valuable, then the Moon is a very valuable target, and there is a reason to solve problems like the 28 days long day. If that's stuff isn't valuable, then the size of the day is an insurmountable issue.

Re: Vast new stores of water reported on the moon

#173

Post by robotresearcher »

fastball wrote: post #147
csomar wrote: post #138

Earlier quoted context omitted.

But shipping from the moon to the earth should be much cheaper? I don't have the math (so someone please do?) but based on the size of the Apollo 11, it seems to be trivial to send stuff to earth.

Escaping the moon's gravity well is basically all you need to get stuff back to Earth.

The machine that does this first has to leave Earth and land softly on the moon before it can start boosting stuff back. You can’t skip the first two steps.

Re: Vast new stores of water reported on the moon

#174

Post by drtgh »

stametseater wrote: post #139
drtgh wrote: post #111

Earlier quoted context omitted.

It is not my field, but if plentiful and accessible, we are talking about several thousand tonnes of water around a small habitat that could theoretically be used. Nevertheless, if I understood right, that immense amount of water would have a limited shelf life until acidification corrodes the containment structures, so it would need to be continuously treated and refrigerated, " Ionizing cosmic radiation is mostly g…

Chemically neutralizing the shielding water should be trivial. But why would the water need to be refrigerated? Energy absorbed from radiation would be emitted as thermal radiation, and lose a ton of thermal energy during the long lunar nights. If well insulated, the water tanks could serve as thermal batteries to keep the rest of the base warm.

I said it for to maintain undesired chemical reactions under control. My first thought after to read some papers would be below 25°C, but this is not my field so take it with a grain of salt, as the water temperature in normal operating conditions within nuclear waste water pools seems to be held below 50°C by the refrigeration systems.

PS. I'm not sure if it would be trivial to treat the water for to keeping it operative more than one year as effective shield.

Re: Vast new stores of water reported on the moon

#175

Post by stainablesteel »

NickM wrote: post #149
stainablesteel wrote: post #126

Earlier quoted context omitted.

a recent megaprojects video claimed harvesting water from asteroids was more worth the time and money than to do the same for rare earth metals. apparently bringing tons of rare earth metals back to earth would only lower their price and therefore not make the trip worth the money, but i guess this isn't a problem for the water that those asteroid might hold as that would still be not only valuable but worth the expe…

That seems like a bizarre take. Even with efficient fully reusable rockets, surely desalination will still be much cheaper than mining water from asteroids and bringing it back to Earth? And sure, maybe bringing huge amounts of rare earth metals back might reduce the price a bit, but to the point where rare earth elements are cheaper per mass unit than water ?

it seems bizarre to me too, i'd also think the practical use of having stores of rare earth metals outweighs their initial value simply due to current inaccessibility but i think the video was saying this as a long-term business strategy wouldn't work, as the cost would decrease over time for the initial cost of all the engineering

i'm unfortunately unable to comment on the economics of space water

Re: Vast new stores of water reported on the moon

#176

Post by Teever »

whatshisface wrote: post #158
wongarsu wrote: post #145

Earlier quoted context omitted.

Impact sites of larger asteroids are also great targets for mining operations. For example there's some speculation about the gigantic impact crater on the far side of the moon containing a gigantic metal lump below the surface https://en.wikipedia.org/wiki/South_Pole%E2%80%93Aitken_basi... https://www.independent.co.uk/tech/nasa-moon-mass-crater-met...

It's not entirely clear to me why you'd want to find asteroids on the moon rather than finding them in space, where the mass wouldn't hardly have to be lifted.

You can build a solar powered space elevator on the moon with existing materials .

Re: Vast new stores of water reported on the moon

#177

Post by Teever »

robotresearcher wrote: post #173
fastball wrote: post #147

Earlier quoted context omitted.

Escaping the moon's gravity well is basically all you need to get stuff back to Earth.

The machine that does this first has to leave Earth and land softly on the moon before it can start boosting stuff back. You can’t skip the first two steps.

Not quite.

The machine that does this needs to be built by a machine that is carried by the machine that is first built and launched from earth before you can start boosting stuff back.

It is feasible to build a space elevator on the moon with existing materials.

Re: Vast new stores of water reported on the moon

#178

Post by fastball »

robotresearcher wrote: post #173
fastball wrote: post #147

Earlier quoted context omitted.

Escaping the moon's gravity well is basically all you need to get stuff back to Earth.

The machine that does this first has to leave Earth and land softly on the moon before it can start boosting stuff back. You can’t skip the first two steps.

You could build a railgun on the moon and launch stuff back to earth.

Re: Vast new stores of water reported on the moon

#179

Post by RealityVoid »

arethuza wrote: post #123
RealityVoid wrote: post #90

Earlier quoted context omitted.

Being exposed to radiation does not make something radioactive. Radioactive particles settling on the thing is what usually causes things to become radioactive. We actually use radioactivity to sterilize food.

Neutron activation will make things radioactive?

I stand corected.

Re: Vast new stores of water reported on the moon

#180

Post by nathan_compton »

Tagbert wrote: post #168
nathan_compton wrote: post #161

Earlier quoted context omitted.

If we ever have a space elevator bringing water down from space could actually be a net negative expense, since you could be using the weight to carry stuff up out of the gravity well.

"If we ever have a space elevator" such a simple phrase doing a lot of rhetorical lifting. The logistics and problems of space elevators make them extremely unlikely in any timeframe that is less than fantasy.

Agreed!
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