One Small Breath For Man

An anonymous reader writes "The New York Times reports on a new technique that may allow Oxygen to be wrung from the soil on the moon. This may pave the way for a moonbase, and allow permanent habitation on Earth's only natural satellite." From the article: "Lunar soil brought back to Earth is in short supply and highly prized, so Nasa researchers have been using matter with the same composition for its tests. The soil contains about 45 per cent oxygen by weight, but it is mostly 'trapped' in the form of silicon dioxide ... At the moment, all oxygen supplies would have to be brought from Earth, which is so expensive and energy-inefficient that it effectively rules out a permanent Moon base. "

Comments

Looky here city girl...

[Anonymous Coward]

Oxygen don't grow on trees.

Water

[MichaelSmith]

I predict that if hydrogen can be extracted from regolith close to the surface, then a lot of that oxygen will be burnt down to make water. During the apollo missions oxygen had to be carried but more often than not water for cooling was the limiting factor for stays on the surface.

Its nice to see that people are working directly on this, even if it will be at least 15 years before anybody walks on the moon again.

Re:Water

[pe1rxq]

Emmm, check your facts.....

Look up 'combustion'.
We use produce CO2 by burning hydrocarbons which contain these little atoms we call hydrogen. These don't magicly disappear, they end up in water molecules.
So you still need to send up food, but the water will be produced by breathing....

Food + O2 => CO2 + H2O + heat.

Isn't energy enough?

[Bombula]

I am no chemist, but I thought that with enough energy it is usually possible to break up compounds into their constituent elements. Is energy in short supply on the moon? Seems like solar and possibly nuclear energy from the moon's deuterium should be able to supply lots of energy. Am I completely retarded here? Probably...

Re:Isn't energy enough?

[Cadallin]

No, you're exactly right. Much of the lunar dust is Si02, the same as sand or glass or quartz.

SiO2 + energy -> Si + O2

Is perfectly valid chemistry. In fact, if you go back to the hard sci-fi of the 50's and 60's this is the kind of shit they predicted we'd be doing RIGHT NOW. Building plants on the moon to convert lunar dust to oxygen (and high quality silicon for chip fabs) for both lunar bases and space stations.

Re:Isn't energy enough?

[shawb]

Nuclear energy: Fission. A lot of the weight of an Earth bound nuclear reactor is shielding and safety equipment which is (quite rightly) mandatory. On the moon? "Oh hell, the reactor's melted down. Good thing we sited it 100Km from the base". BTW. We *have* sent nuclear reactors into space - you don't think Voyager is running on car batteries, do you?

The Voyager probes are technically nuclear powered, but it is not the same beast as in a chain reaction fusion reactor. The probes use an RTG which converts some of the heat released from natural radioactive decay into electricity. These do not produce electricty on nearly the same scale as a thermal fission reactor. The RTGs in the Voyager probes are generating about 300 Watts. That couldn't even power some gamers' desktop computers, much less a large scale SiO2 -> Si + O2 manufacturing process. Granted, a large number of RTGs could be used, as well as using larger and more efficient RTGs, but it seems likely to me that the amount of PU-238 (as well as some of the more exotic materials needed to drive the process would be cost prohibitive for any useful amount of oxygen.

All that, and RTGs still need a way to get rid of excess heat, as a thermocouple relies on the difference in temperature to produce electricity. The amount of heat that needs to be removed from a voyager level RTG is not that significant and can probably be accomplished through simple radiation, but the amount needed to drive a major industrial process would require some fairly exotic cooling techniques (although on the lunar night a good portion of the waste heat could be reclaimed to heat living quarters, etc.

Another addiction

[Anonymous Coward]

Picture it. Fights between "our reserves are finishing soon" versus "it's going to last for long".
Campaigns on the line of "Have children, they'll only take n cubic metres of soil per year".
New religions venerating resurrection via burial: "Oxygen you are and in oxygen you'll become".
Mr President Of The Moon declaring "We as a nation have an addiction to oxygen".

Re:Can this article be even more pretentios?

[mattmacf]

Read TFA:

To extract oxygen from lunar soil, scientists used a lens-like structure to focus sunlight on to it, heating it to 2,500C.

In Nasa's latest tests, a 12ft-wide dish was used to concentrate the sun's rays on to 100g of a substance similar to Moon soil. After a few hours, one fifth of the substance had turned into oxygen.

Now tell me, how hard was that?

Dammit!

[Arivia]

The article title made me think /. had finally opened its' much-awaited Corsetry section...

Not so hard to bring from Earth

[techno-vampire]

Oxygen isn't as hard to bring from Earth as you might think. Not only do you have to bring air to breath, you have to bring water, both for drinking and for cooling. Once a base is set up, some of that water can be broken down, releasing oxygen. Not only that, the food you carry there also contains oxygen. Part of the base will be a greenhouse, fertilized by waste products and converting CO2 into O2, plus part of the colonist's food supply. If there's too much organic waste, some of it can be incinerated, leaving (mostly) water and CO2, both of which the greenhouse can use. Yes, if we can't get much oxygen out of the regolith, we'll have to ship it up, but that's a one-time expense, not an ongoing one.

Silicon Dioxide

[Inda]

Fact: Silicon dioxide is also known as silica.

Fact: Inhaling crystalline silica dust can lead to silicosis or cancer.

I thought they were amusing facts. +1 Important please Mods. :)

Re:Please pay attention

[1u3hr]

Only the English are inconsistent with their acronyms where they capitalize BBC but not NASA. So much for the cradle of their namesake language.

That modded "informative"? How about "ignorant flamebait"?

The usual UK rule is to preserve caps when you pronounce the letters: (B-B-C) but to use normal case when you pronounce it as syllables. Thus: Nasa, UN, Nato, snafu, UK.

Re:Can this article be even more pretentios?

[ian_mackereth]

One of the prime differences between doing this on Earth and on the Moon is that vacuum is more plentiful on Luna than it is on Terra.

This lowers the temperature required to disassociate the SiO2, making the engineering sufficiently feasible.

Well, that's what _this_ group says to the funding body within NASA, anyway!

Re:Can this article be even more pretentios?

[cruachan]

2 days ago...

Science Ability Down in U.S. High Schools
http://science.slashdot.org/article.pl?sid=06/05/2 7/1639243

How true.

Still not terribly efficient...

[mattmacf]

I'm no chemist either but I did take a high school chem class a few years ago. I'm far from confident in my calculations, so feel free to correct me if I'm egregiously wrong, but AFAICT the amount of energy needed might be a limiting factor. Now, the article gives us two tidbits of information.

In Nasa's latest tests, a 12ft-wide dish was used to concentrate the sun's rays on to 100g of a substance similar to Moon soil. After a few hours, one fifth of the substance had turned into oxygen.

and

The soil contains about 45 per cent oxygen by weight, but it is mostly 'trapped' in the form of silcon dioxide.

Now assuming that one fifth of the 45% of the oxygen in the soil is 100% oxygen, we yield a total of 9g of pure oxygen. A quick trip to Google tells us that oxygen has a molecular weight of (roughly) 16. Therefore, 9g of oxygen translates to 0.5625 moles of pure oxygen. Another check of Google tells us that the volume of oxygen at STP is 17.36 x 10^-6 cubic meters/mole. We finish our Google-sponsored portion of this post by converting to give us 17.36 mL/mol. Multiplying by our previous result (0.5625*17.36) gives us a whopping 9.765 milliliters of oxygen. So how much exactly is that?

We continue our inquiry at the wonderful world of Wikipedia. We learn that the Earth's atmosphere is only 21% oxygen, so our 9.765 mL of pure oxygen effectively becomes 46.5 mL of normal air. Our final reference tells us that the average human breath exchanges 450-500 mL of air.

Putting this all together, we get a notably unimpressive result. The "few hours" that it takes to bake oxygen out of moon sand creates only enough oxygen to support one-tenth of one ordinary resting breath for one average-sized adult male.

I really hope I'm off by an order of magnitude or four, but unless I'm terribly wrong (entirely possible), this technology has a long way to go. The final line of the article does give hope, however: "Alternative methods to extract oxygen from Moon soil are also under investigation, including melting the rocks into a liquid and freeing oxygen with an electric current." Obviously NASA realizes this plan still needs work. Hopefully

Not Quite

[FasterthanaWatch]

The standard molar volume of most any gas is still 22.4 L/mol so 8g of Oxygen would be 5.6L of oxygen. Throwing in a ratio of 25% Oxygen, and we end up with over 20L of air.

Still not sure how you got that other figure, but perhaps it refers to the liquid form.

Re:Not Quite

[DeepStream]

I am a chemist, and the number you have for the molar volume is quite simply wrong (at least at STP). O2 behaves reasonably close to an ideal gas, and does in fact have a molar volume around 24L at STP.

If you think carefully about the numbers you got:
9g to 9.7 mL gives you a density of ~1 g/mL, which is that of water, not that of any gas at atmospheric T/P.

As a previous poster mentioned, you're much closer to getting 50L of breathable air (at 25% O2). While not a very large amount (1 cubic meter is 1000 L), 100g of rock isn't a whole lot either.

The simple fact is that SiO2 is about 50% oxygen by mass, and you can get a LOT more moon rock than you can either liquid O2 or water.

Re:Can this article be even more pretentios?

[ComaVN]

People, people, you got it all wrong.

The reaction is: Earth+Fire=Air.

Don't they teach proper alchemy anymore?

So when we get to the moon for the first time...

[Somatic]

we can test that.

Mod parent up (Read: I'm flat out wrong)

[mattmacf]

Like I said, I'm no chemist. Obviously, your comment about density clearly shows a glaring flaw in my calculations.

I think the point I should've make clearer is the fact that the energy required to release this (relatively) miniscule amount of oxygen is astronomical (no pun intended). Even assuming that I'm wrong about my interpretation of the article and that a full one fifth of the 100g of the sample becomes oxygen, that we get a total of 20g of O2 or roughly 100L of breatheable air. In order to release this, we need to heat a quantity of 100g of SiO2 to 2500C for several hours. As the article stated, this requires the concentration of sunlight from a 12' wide dish onto a sample of just 100g. I'm not exactly sure how much energy that is (and I'm not about to try and calculate it), but it seems like an awful lot. Hopefully this technique scales incredibly well or the alternate methods of liquifying or electrocuting the sand have more promise. I realize this is fledgling technology were talking about, but it still looks like it has a long way to go.