The First Word of Water on the Moon.

The Following was witten 1 year before the public announcement of possible water ice on the South Pole of the Moon. For those that are mystified as to why it took so long, I was told that it was a paper organization and readability problem, not a technical issue. But, it was not necessarily a closely held  secret, it was  just not officially released until a lot of people were happy with the paper. Another problem was what agengy would release the news. This was not a NASA mission, it was a BMDO mission. The release of scientific findings from the DOD was unusual but not unheard of.

The Biggest News by Far:

Did Clem see water? Well ,as we post this (Nov 95),a bunch of young scientific turks are trying to convince senior planetary scientists, that their findings indicate evidence of water on the moon. On the South Pole to be precise. Current rumor is they will publish in Nature magazine, real soon now.

Note: It was Published in Science Magazine a Year after I made the comment above. For the full report try here. It is in the 28 Nov. 96 issue.

The Experiment was for the Bistatic Radar to look at the surface, and below the surface, much like archeologists and paleontologists use radar to look under the surface for their favorite objects. Clem saw something that indicated a frozen body of water. Looking through the ice the surface of the moon made a second return. This got the people in the control center rather excited. So excited, in fact, they did it again. Two BSR runs. This evidence is to be confirmed or verified by the Lunar Prospector, which is purpose built to find water, among other things. Where did the water come from?

For the past 4.6 billion years the moon has been collecting water in the form of cometary ice. A couple  hundred or thousand metric tonnes of comet hitting the moon every year for 4.6 billion years. How can the moon not be a swamp, you ask? Well, it is ,sort of, a frozen swamp.

But let us look at the direct evidence.

From the Clementine collection at the NRL:

This shows three perspectives of some interesting Bistatic Radar Doppler Image data created by the Clementine spacecraft and recorded at the DSN. The top view shows a "waterfall" plot of the Fourier-transformed raw data, in which the S-Band Carrier appears as the narrow diagonal line sloping down to the left. The lunar reflected radar signal is the rainbow-colored broad, diagonal band sloping down to the right.

The middle view is a processed image that has been realigned using the S-Band Carrier as the left-hand border.

In the bottom view, the Moon's south pole appears in the radar signal as the vertical dark blue band. Horizontal bands represent thermal noise, and are due to receiver gain changes at DSN during the data collection. This data is being analyzed for the possible presence of ice on the Moon. The interesting part is the pale green band on the left of the vertical band. Is it a true return of something encountered on the way to the surface? Some would say "You Betcha!"

Polar only versus Water everywhere:

As the moon rotates through its day of about 27 earth days, the surface gets hot on the day side and very cold on the night. If there are any comets laying on the surface several things happen. The cometary volatile gasses begin to boil off, and the water begins to melt, then flashes to vapor because the melting point is very close to the boiling point. You have all seen the spectacular cometary tails streaming away from the solar wind, as the comet falls into the warm zone close to the sun. This same thing would happen if the comet were to land on the moon. If it impacted on the day side the volatiles and water would continue to boil away, and stream  slowly away from the suns rays. This would give the appearance of a low lying fog. The floating molecules are not instantly destroyed, they are just pushed by the sun. Some of the molecules are separated into constituent atoms  (called dissociation) by the energetic UV rays of the sun. The ionization of water has been calculated. This ionization process ,would occur whenever the ultra violet rays, or the solar wind from the sun hit the vapor molecules, long enough for the hydrogen to separate from the oxygen. During a 14 hour period on March 7 1971, the surface science package of Apollo 14 detected a very large water vapor cloud.  An hour later the still operating scientific package on Apollo 12 confirmed the anomaly. It was much larger than could be explained by dumping from the Apollo 14 CSM, 1 month earlier. The conclusions of a report written at the time, indicated a strong possibility of water vapor from the moon itself.

The sun goes down and some isotopes recombine into water ice molecules or form molecular hydrogen from the various atoms. The molecules are effected more by gravity than the solar wind. They sink to the surface and contact some particle of regolith. Some molecules fall through the regolith particles until they contact a particle beneath the surface. These will be protected from the sun when it next rises. There is another form of ice separation into constituent molecules that occurs during the night. This process is called sublimation and all ices are subject to sublimate.  But compared to the daytime activity, sublimation is very slow and, when it gets too cold, sublimination stops.

The thing that has not been fully addressed by the holders of the "Dry Moon" premise is that comets can hit hard enough to bury themselves. The data from the Apollo series seemed to indicate that at or near the equator the regolith was dry. But less than 1 meter below the surface, at the equator, the moon never exceeds the freezing point of water.  At the south pole, the sun never penetrates to the crater floors. Every one could be a perpetual icebox. At the north pole the sun does partially illuminate most of the crater floors. But it is a very low sun. The regolith may never reach the magic 0 degree C temperature that would allow to water to melt, then vaporize in the lunar vacuum. These speculations that water must exist below the surface are not without data to support them.  Nor or they original with this author. Astronomers such as Gold, 1960;  Green, 1964; Schubert, Lingenfelter, and Peale, 1970; Freeman, Hills, and Vondrak, 1972;  and others, have all posited variations on the wet moon hypothesis.

The existance of water would provide the single most important impetus to the manned exploration of Space. The Moon is a stepping stone. It is part of the land bridge to Mars and beyond. Lunar Water would allow mankind to start to build the infrastructure that will put us into space to stay. Fortunately, the dream of water on the moon is being backed up by hard scientific data. (15 Nov. 1995)

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