Thursday, September 24, 2009

What's different about this 'discovery' of water on the Moon?

Joel Raupe

First, a distinction should be made between the water we hope to liberate with LCROSS and the water making news today.

The water we hope to expose using using kinetic energy supplied by the Moon's gravity together with the mass of the two-ton LCROSS and its gathered momentum during October 9's terminal descent into Cabeus A has probably been accumulating for a very, very long time. The hydrogen detected using Russian-built neutron spectrography aboard Lunar Prospector (1998) and confirmed by LRO this past summer is confined to the polar regions. As discovered by Prospector and now confirmed by LRO, this hydrogen signature is not confined to the permanently darkened regions. It is at its most "chunky" in those cold spots, shadowed regions and micro-shadows, however

It also now appears likely that the lasting water near the poles of the Moon has some of its origin in the process decyphered nearer the equator. The hydroxels and water frost detected throughout the lunar surface and making the news today may in part be a by-product of the solar wind.

As recently as June 2008, neutral hydrogen was unexpectedly detected in the solar wind. It was unexpected because, at its most basic the Sun is "a mass of incandescant gas" where "hydrogen is turned into helium at a temperture of millions of degrees."

The detection of hydrogen in the steady solar wind, previously thought to be composed mostly of helium speaks to the unexpected inefficiency of the Sun but some of this hydrogen is in the mix of particles that steadily bombard the lunar surface with the solar wind, cosmic rays and micrometeorites that constantly "garden" that surface, and some of this hydrogen apparently combines with oxygen when liberated in this mix from the compounds that make up the Moon.

In the form of water and hydroxel molecules, these volatiles linger in the predawn and quickly dissipate at sunrise. Though most is then lost to the vacuum of space some of these molecules end up bounced to the "cold traps" of the permanently darkened regions, craters and micro-shadows of the lunar poles.

At least some of the water LCROSS was designed to uncover arrived on the Moon in the form of comets and cometary fragments and may have been been accumulating in the super-cold and permanently darkenen regions, craters and in micro-shadows that increase in number above 70 degrees latitude toward the lunar poles for a very long time. Some of it was covered up and buried, protecting it from sun and space and not exclusive to the polar regions.

Even as close to the equator as Mare Crisium, where the last lunar sampling mission in 1976, Lunar 24, cored into the mare-material to a depth. In those samples, to put it very simply, the Soviets found "holes" in the compounds that may have once been filled by hydroxels and H2O. Another extrapolation of their analysis seemed to indicate this phenomena increased with depth.

The water on the Moon they are talking about in Houston right now is likely to be a transitory phenomena, but as a by-product of the same processes that create and dissipate these molecules is probably an explanation for the more long-lasting hydrogen and water that manages to bounce into the permanent dark, both large and small, nearer the poles.

The next time you look at a Full Moon, remember there's water being "created" and destroyed there all the time, and it's been going on for 4.575 billion years. There may be a juicy moon up there, and in more places than we ever dreamed during the Apollo Era.

No comments: