I've been writing a lot lately for h+ magazine.

My latest story is about the Moon and the hydrogen that NASA found there.

...the building blocks of water, hydrogen and oxygen, are already everywhere -- all over the Moon. We know that water is created naturally from meteors striking the surface and flash-heating the regolith, which causes iron oxide to be gradually reduced by the hydrogen implanted by the solar wind. The hydrogen in the regolith reacts with the oxygen in the iron oxide to create water. This water, generated on or deposited onto the Moon, is either lost to space or migrates to higher latitudes. The southern polar region, with its permanently shadowed craters, is thought to retain water and other volatiles more efficiently than any other region. We also know that water is deposited into the poles directly via cometary tails that periodically envelope the entire Moon.

Does that mean we can just use the water that's already there? Well, most experts agree there are two main sides to that issue. "Water is water. If you can find it naturally, that's better than having to resort to a chemical combination of hydrogen and oxygen, which requires energy to activate the process," explains Donald Sadoway, a Professor of Materials Chemistry at MIT who has developed a "molten oxide electrolysis" technique for extracting oxygen out of Moon regolith. "However, if the water is to be potable, then purity is an issue. So in any given situation, you need to assess whether it is more costly to purify existing water or to synthesize water from hydrogen and oxygen."

(Above: NASA LCross photo by Northrop Grumman)

To get to the bottom of things, NASA is dropping a completely empty upper stage of the Centaur rocket smack into one of these southern polar craters. Contrary to some inaccurate reports in the popular media, there will be no explosives or military weapons involved. The upper stage is from the LCROSS and LRO's launch back in June, which was retained for this experiment.

"It weighs roughly 2,200 kilograms, and will be moving at about 2.5 kilometers per second (5,600 miles per hour)," explains Day. "It will be coming in very steep, at about 80 degrees, and will make a large enough impact to loft approximately 200 metric tons of material about 10 kilometers into the lunar sky, where it will remain long enough for the LRO and ground-based assets to obtain their data."

NASA is making sure that it comes in at a sharp enough angle this time to cause a recognizable plume or other reaction from the surface. The angle wasn't steep enough when they crashed the Lunar Prospector into the crater in 1999, with no discernable results.