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Posted by: MorrisJones Sep 23 2009, 05:19 AM

This is a personal theory, explained in the article. Time will tell if I am right or wrong.

http://www.moondaily.com/reports/Argon_On_The_Moon_999.html

I don't know if argon deposits would be as useful as water, though.

Posted by: Phil Stooke Sep 23 2009, 12:54 PM

Well, if you can figure out how to use it for rocket fuel and life support...

Phil

Posted by: ngunn Sep 23 2009, 01:02 PM

Maybe as a dilutant in the breathing mixture in place of nitrogen?

Posted by: AndyG Sep 23 2009, 01:51 PM

Norman Foster will need it when http://www.guardian.co.uk/artanddesign/2009/sep/22/moon-norman-foster-architecture are welding on the Moon.

Posted by: centsworth_II Sep 23 2009, 05:01 PM

This from the http://en.wikipedia.org/wiki/Argon is interesting:
"....argon can form clathrates with water when atoms of it are trapped in a lattice of the water molecules."

It will be interesting to see if large amounts of both argon and water are found by LCROSS.

Posted by: Greg Hullender Sep 23 2009, 05:15 PM

Not sure if anyone has measaured argon narcosis at just one atmosphere, but since it's 2.3 times worse than nitrogen and some people seem to feel effects from nitrogen at less than three atmospheres, I'd guess that using argon instead of nitrogen would make the crew slightly stupider than normal.

An ion drive could use argon instead of xenon for fuel, of course, but it'd have even less thrust (athough better specific impulse).

Seems like more of a curiosity than anything useful -- any time soon, anyway. Someone might find a cool use for it, but I don't see anything obvious that would obviously work. :-)

--Greg

Posted by: Juramike Sep 23 2009, 05:27 PM

Might be useful to explain how the volatiles got there. Isotope ratios might help tell if it got delivered from comets or was derived from internal radioactive decay.

-Mike

Posted by: Greg Hullender Sep 23 2009, 05:57 PM

That's me thinking like an engineer and not a scientist! Yeah, that makes sense. Also, presumably it would be mixed with other volatiles, each of which would tell its own story.

--Greg

Posted by: nprev Sep 23 2009, 06:16 PM

Question: Is there any practical way to determine Ar isotopic ratios remotely? Nothing springs to mind.

Also re applications: Argon's a very good thermal insulator, so it might be useful for that application in future lunar construction.

Posted by: Greg Hullender Sep 23 2009, 06:22 PM

Yeah, I thought about that too, but then I remembered that vacuum is an even better thermal insulator. I'm told the moon has large deposits of that already. :-)

--Greg

Posted by: nprev Sep 23 2009, 06:45 PM

Yeah, but vacuum's TOO good in some ways; disposing of internally generated waste heat becomes a real problem. Argon's got some thermal inertia, so you can dissipate heat over the entire surface area of a container/structure instead of building an overly elaborate radiator system that has to work through structural penetrations.

Posted by: ngunn Sep 23 2009, 07:01 PM

Interesting, though I don't find any mention of toxicity when looking around. For example this is from Wikipedia:

Although argon is non-toxic, it does not satisfy the body's need for oxygen and is thus an asphyxiant. Argon is 25% more dense than air and is considered highly dangerous in closed areas. It is also difficult to detect because it is colorless, odorless, and tasteless. In confined spaces, it is known to result in death due to asphyxiation.

And after all we breathe it all the time at 1 percent. Now that the question has cropped up I'm really curious to know one way or the other.

Posted by: Juramike Sep 23 2009, 07:07 PM

Argon will sit heavily in your lungs if you breath in a lot of it in high concentrations. (At normal concentrations in air, it's not a problem).

Argon will make a nice inert blanket. Unlike nitrogen, air (i.e. oxygen) won't diffuse down through it. I've isolated very air-sensitive materials under an argon blanket in an open flask.

Argon-filled balloons are kinda neat. They drop right to the floor.

Posted by: ngunn Sep 23 2009, 07:44 PM

Also interesting. You wouldn't want your Moon base chest-deep in neat argon or it would be dangerous to sit down! Also an undue concentration of oxygen near the ceiling would pose a fire risk. However maybe these problems would be less severe or even insignificant in low lunar gravity, especially with the air being constantly circulated to remove CO2.

Posted by: Greg Hullender Sep 23 2009, 07:49 PM

Check out the sidebar on the right, listing the relative narcotic potency of different gases:

http://en.wikipedia.org/wiki/Nitrogen_narcosis

If you had a 20% oxygen, 80% argon mix at one atmosphere, over time, that could cause some narcotic effect in some people. I couldn't find any evidence that anyone has actually tried this experiment, though.

--Greg

Posted by: ngunn Sep 23 2009, 08:04 PM

Ah, thanks. Only marginally more potent than oxygen though, I see. Maybe something like 30 percent oxygen 70 percent argon at, say, 0.7 atmospheres would work?

Posted by: Greg Hullender Sep 23 2009, 08:06 PM

I'm starting to worry that we may be wandering too far off-topic for UMSF (if not totally violating the rules against blue-sky engineering), but this is an interesting idea. So are you suggesting that for, say, metallurgy on the moon, eliminating waste heat simply through radiation may be too slow, and building a radiator with big cooling fins might be too expensive and/or cumbersome. So, given cheap, local argon, you might fill a large bubble with argon, do the work inside the bubble, and let the heat radiate out through the (much larger) surface. Is that the general idea?

I know that some metallurgy on Earth is done under an argon blanket (as Mike described using) to control the amount of oxygen reaching the metals, so I suppose there might be other advantages.

--Greg

Posted by: ngunn Sep 23 2009, 08:10 PM

True. I'm dropping out of this one now, but thanks for all the interesting replies up to this point.

Posted by: stevesliva Sep 23 2009, 10:21 PM

You know you're a geek when you mention "neat" balloons and they're not filled with He or N2O.

Posted by: Vultur Sep 24 2009, 03:09 AM

Quite possible - anyway, 3 psi oxygen isn't a total requirement, otherwise anyone who climbed a hill would suffer anoxia. Plenty of people in mountainous regions get 2.5 psi or less.