Abstract:

Planetary Ice, Lunar Ice, Lunar Helium 3 and the Real Opening of the Final Frontier

William J. Webster, Jr.
Laboratory for Terrestrial Physics
NASA’s Goddard Space Flight Center
Greenbelt, MD 20771
 

“Welcome to Reality, Captain Kirk!”

Beyond the asteroid belt, water is common.  The most common solid surface in the outer solar system is water ice of varying levels of purity.  The gas giant planets themselves all contain substantial fractions of water in their atmospheres and their rings are mostly water ice particles.  The consensus understanding of the formation of the solar sys twenty years ago regarded this as entirely expected.

The average temperature of the protosolar nebula was expected to allow volatiles like water to accumulate only in the outer solar system.  The terrestrial planets were expected to be depleted in volatiles because of their proximity to the heat source that became the sun.  As a result, it was felt the direct colonization and economic exploration of the inner solar system was beyond reach.  Any volatiles needed for survivale ( to say nothing of industry) would have to be imported either from Earth or from the outer solar system.  The nearest source of significant volatiles off the Earth seemed to be the asteroid belt.  Because of this, the more perceptive writers of the hard science fiction in the 1970’s and 1980’s had extraterrestrial industry concentrated in the belt.

This was a well thought out and entirely self-consistent theory and all of the initial results from planetary exploration completely supported the theory.  However, we now know that this theory is completely wrong.  Water, either in liquid or solid from, is or has been present on all the terrestrial planets in varying abundance and from varying sources.  The evidence for water and water ice on Mars became especially clear with the recent Mars Pathfinder mission.  Clean and unambiguous evidence of a past flood at the landing sits has given extra credence to work suggesting that Mars was wet and warm in the geologic past.  Venus atmospheric chemistry suggests that Venus had a deep primordial ocean, which was lost due to the runaway greenhouse effect. Radar observations of Mercury have strong evidence for water ice deposits at the Mercurian poles.

In the case of the Moon, the Clemetine bistatic radar experiment provided some evidence for ice at the one of the lunar pole.  However, the results from the Lunar Prospector mission have shown that the cold traps at the lunar poles contain vast amounts of water ice and that the equatorial regions (especially the maria) contain an abundance of solar wind deposited Helium three much in excess of Apollo era expectations.

These seemingly esoteric science results and the theory revolution they spaawned are the key  to the opening up of the inner solar system for human exploration and economic exploration.  Unlike the expectations of the 1980’s, the first major industrial complex off the Earth will undoubtedly be on the Moon.
 

William J. Webster, Jr. received the B.S. degree in Astrophysics from the University of Rochester, NY in 1965 and the Ph.D. degree in Astronomy from the Case Western Reserve University, Cleveland, OH in 1970.

He was a National Academy of Science-National Research Council resident research associate at Goddard in 1970 and joined the staff in November of 1971.  He is presently a member of the Terrestrial Information System Branch of the Laboratory for Terrestrial Physics and is Deputy instrument Manager for the MultiBeam Laser Altimeter, the sole instrument on board the Vegetation Canopy Lidar Mission spacecraft Scheduled for launch in May 2000.  His research interest includes planetary exploration, comparative planetology, planet magnetic field, asteroids, stellar formation, and tethers in space.