It seems like NASA’s LRO mission has inspired an awful lot of renewed interest in the Moon, recently. Bloggers, twitterers and forum runners alike have all been posting a lot of Moon-related things lately, and personally, I think it’s brilliant. Perhaps if enough people are interested, the governments might finally give such ventures more consideration. Hey, I can always hope, right?
One thing a lot of people seem to get hung up over is the question of water, and in honesty, it’s a fair thing to be concerned about. Any permanent lunar habitat would obviously need a suitable quantity of water for people to live there. Most evidence points to the fact that the lunar surface is completely devoid of water. This does pose something of a problem.
On the other hand, a lot of people still believe it’s open to debate. The idea of ice in deep craters is not a new one. It’s a simple concept. Normally with the sunlight that hits the lunar surface, water would either boil off rapidly into space, or be split into hydrogen and oxygen. Which would then boil off into space. The moon isn’t a friendly place for small molecules to live. On the other hand, if some craters near the Moon’s poles are deep enough, they may never see sunlight. If this is the case, then they may actually remain cold enough to retain some amount of ice indefinitely. After all, the Moon’s surface is a chilly -165°C in the shade. That should be just fine, right?
Personally, I’m skeptical of the idea. Even at such a low temperature, a few million years worth of vacuum ablation would surely remove most of not all of the water. Entropy would see to that. Through good old fashioned thermodynamics, I’d expect any reserves of ice, even in deep craters, to have been lost to space by now, molecule by molecule. Though I’ll freely admit that there might be something I’m not considering there (thermodynamics and I never really got on that well). All the same, it seems… implausible.
Below the surface? Well, that’s another matter. It seems like there might have been water in the Moon once upon a time. How long any pockets of ice could persist are anyone’s guess though, especially given the daytime temperature of 110°C. If there are subsurface pockets of water, they’d probably exist as veins, the way minerals do on Earth. Future lunar colonies might need to actually mine for water.
There seems to be one big thing though, that no one’s really talked about. Why don’t we just make the water once we’re there? All the right ingredients are in place (well, hydrogen and oxygen). The trouble is the oxygen is chemically bound up in minerals, and most hydrogen on the moon is from the solar wind. The fact remins though — If someone could devise a feasible way of isolating the right chemicals and splitting them apart, they could be reacted together to produce water. How easy that would be is a good question. For fairly obvious reasons, no one’s ever had to devise a chemical process to make water before.
Perhaps a modified version of the Hall-Héroult process — the process used on Earth to extract aluminium from alumina (Al2O3). That would give the added benefit that it would also produce aluminium, which would be an extremely useful engineering material on the Moon. Alternatively, perhaps it could be as simple as reacting hydrogen gas with nickel oxides.
It may be true that I’m no expert on lunar mineralogy, but as the old saying goes, ‘if you can’t lead a horse to water…’