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600 Million Tonnes of Water Ice Found on the Moon

Posted by: sanman - Wed Mar 03, 2010 4:09 am
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600 Million Tonnes of Water Ice Found on the Moon 
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Post Re: 600 Million Tonnes of Water Ice Found on the Moon   Posted on: Sun Mar 07, 2010 2:39 pm
I doubt that any asteroid would have more water than on the Moon, as we just haven't seen all the available lunar water. That's why I'm wondering if there's more waiting underground, far below the lunar surface. Asteroids have the lower/negligable gravity well, though.

Rather than ground-based repeaters, just use an orbiting communication relay. Surely it's easier to launch something into orbit around the Moon than to lower it down to the ground there.

What is the height of lunar-synchronous orbit? Or would the L1 zone be good enough?

I'm wondering if a surface rover could be powered by a microwave-beam from an orbiting satellite. Then you could have as many rovers as you like down there, each being fed in turn by the beam which can easily be redirected. Then you don't have to worry about nuclear power supplies, etc, for the dark zones.


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Post Re: 600 Million Tonnes of Water Ice Found on the Moon   Posted on: Sun Mar 07, 2010 2:51 pm
sanman wrote:
Rather than ground-based repeaters, just use an orbiting communication relay. Surely it's easier to launch something into orbit around the Moon than to lower it down to the ground there.

What is the height of lunar-synchronous orbit? Or would the L1 zone be good enough?

You can't put a satellite into a lunar-synchronous orbit over the poles. That's where those deep dark craters are. Lunar-synchronous over the equator is useless because any rover with line of sight to the satellite could probably see Earth as well. Same applies to the L1 point. A small constellation of polar orbit satellites is what is required, the number would depend on how regularly you needed to contact the rovers.

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Post Re: 600 Million Tonnes of Water Ice Found on the Moon   Posted on: Mon Mar 08, 2010 6:27 am
keep in mind that ice at 30K is just as hard as rock, if not harder. so when thinking about extraction, it is literally the same as mining rock. none of the extraction techniques that you might think are relevant for ice actually are, except heating it and capturing the escaping gas, or cutting it and moving it somewhere else before heating. one possible extraction method that might be nice would be to have a movable mirror on the rim, which directs sunlight onto an area of exposed ice covered by a transparent shell. the ice under this shell sublimates, and the water vapor is re-frozen on some surface outside of the light. then, the ice may be transported by conveyor or somesuch out of the shadowed region and to a lunar base where it can be melted using sunlight again. that would only of course be viable for fairly large deposits as it requires infrastructure. for smaller deposits, i'm sure that cutting it and transporting it would be much better. keep in mind though, most of the "water" on the moon is not in the polar cold traps, it's waiting to be created in a fuel cell from solar wind based hydrogen trapped in regolith and oxygen trapped in rocks.

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Post Re: 600 Million Tonnes of Water Ice Found on the Moon   Posted on: Mon Mar 08, 2010 7:36 pm
You're right, it might be much easier to extract water from the regolith than from the ice traps at the poles, which may be at deep elevations.

As a matter of fact, there are already methods being tested to extract water from the regolith:

http://www.msnbc.msn.com/id/33109285/

http://www.physorg.com/news175198787.html

http://www.newscientist.com/article/dn1 ... nline-news

I'm wondering if one could also leverage the natural day-night cycles of the Moon for extraction, since you know that at some point during the day-night transition, the temperature would similarly be transitioning to a point where the water is getting ready to sublimate. Harvesting at this time of day might reduce the energy requirements. I assume that your harvester would be working close to round the clock, but during those particular times of day they would give a better yield for less power expenditure.


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Post Re: 600 Million Tonnes of Water Ice Found on the Moon   Posted on: Mon Mar 08, 2010 8:49 pm
sanman wrote:
I'm wondering if one could also leverage the natural day-night cycles of the Moon for extraction, since you know that at some point during the day-night transition, the temperature would similarly be transitioning to a point where the water is getting ready to sublimate.


Going slightly off topic here, but that reminds me of a concept I once had for a solar powered moon rover. It was shaped like a rugby ball or lemon and was made up of segments just like a lemon. The robot electronics were contained in a central core and the segments were individual gas-tight bags which contained a tiny amount of water. During a lunar day, the sun would heat the water on one side of the rover creating vapour/steam inflating the segment and pushing the rover slightly. Meanwhile another segment is moving into the shadow of the central core and would freeze out deflating the bag. I proposed this idea for the FredNET rover since all the rover has to do is move a certain distance. No precise steering was required, or possible. I don't believe in patents or intellectual property so if anyone wants to use this idea, be my guest.

Apologies for the off-topicness

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Post Re: 600 Million Tonnes of Water Ice Found on the Moon   Posted on: Mon Mar 08, 2010 10:50 pm
What kind of special precautions would have to be taken to have equipment operate in environments close to absolute zero? Graphite or even fullerene lubricants?


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Post Re: 600 Million Tonnes of Water Ice Found on the Moon   Posted on: Mon Mar 08, 2010 11:08 pm
Another thing - they're saying the water has to be in very pure form for it to be showing up on the mini-SAR's radar:

http://www.nytimes.com/2010/03/09/scien ... 9moon.html


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Post Re: 600 Million Tonnes of Water Ice Found on the Moon   Posted on: Tue Mar 09, 2010 4:24 am
sanman wrote:
I'm wondering if one could also leverage the natural day-night cycles of the Moon for extraction, since you know that at some point during the day-night transition, the temperature would similarly be transitioning to a point where the water is getting ready to sublimate. Harvesting at this time of day might reduce the energy requirements. I assume that your harvester would be working close to round the clock, but during those particular times of day they would give a better yield for less power expenditure.


the day-night cycle on the moon doesn't affect the water there at all (if it did, it would already be gone). the transient water you're thinking of is way too small quantity to be useful. what's useful is hydrogen trapped in regolith. but it's just that - trapped - not free. so the temperature on the surface doesn't affect it. however, mining on the surface has higher temperatures which means the equipment is easier to make.

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Post Re: 600 Million Tonnes of Water Ice Found on the Moon   Posted on: Tue Mar 09, 2010 4:56 am
Until rovers can go across the ice areas, it is useless to speculate on how to extract the ice. Probably any scheme involving sublimating will require too much energy and have problems trapping the vapor.

Probably, drilling, mechanical breaking up will work, and can be done robotically once the material is characterized by earlier visits.

Probably the ice is not exposed to the vacuum, but under a layer of regolith, as even cold ice will sublimate. The mean temperature in that region can be calculated and might be 200 K or so.

Best thing is to think of ways to get robots to the moon and less on what to do after getting there. Without the means there will be no mining. Ever.

A pathway to there must be started--and it looks more and more that NASA will not ever lead there. Google "microlaunchewrs"


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Post Re: 600 Million Tonnes of Water Ice Found on the Moon   Posted on: Tue Mar 09, 2010 10:41 am
ckpooley wrote:
Probably the ice is not exposed to the vacuum, but under a layer of regolith, as even cold ice will sublimate. The mean temperature in that region can be calculated and might be 200 K or so.


I disagree. My research tells me that water ice below 190K will not sublimate. The nighttime temperature on the surface of the moon is about 120K and I'm pretty sure that the permanently shadowed craters would be even lower than this.

I also disagree that it is useless to speculate on methods for extracting the ice. The amount of energy required should at least be estimated before sending rovers into those craters. It's easy and cheap to do the theory side of the work, and even if the results turn out to be inaccurate, the work can be built upon later, not completely discarded.

johno

edit - Apparently the LRO spacecraft measured a temperature of 26K in the Hermite crater http://en.wikipedia.org/wiki/Hermite_(crater)


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Post Re: 600 Million Tonnes of Water Ice Found on the Moon   Posted on: Tue Mar 09, 2010 2:52 pm
I agree that it's perfectly fine to speculate on various scenarios for water extraction, since all or at least some may be applicable to lunar water, which is now being revealed to exist in various forms.

Water is the elixir of life, and so there's a lot of reasons to put in much thought in how to extract it - this isn't just any old substance. It's also a common material whose properties we are well acquainted with, and thus there is scope for a broad spectrum of thought on how to extract it.

http://spectrum.ieee.org/video/aerospac ... um-cleaner


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