Clementine has discovered that the dust on the Moon's surface is less packed than expected. Only about 5 per cent of the space is occupied. The observations were reported by Bonnie J. Buratti of JPL. Clementine mosaics of the Moon at 1 km resolution appeared in Astronomy magazine for June 1995, p. 24.
Lunar Prospector is the name of a probe that NASA plans to send to the Moon in 1997. It is in NASA's program for small, relatively inexpensive spacecraft; Lunar Prospector's budget is "only" $59 million. It will map the lunar gravity and magnetic fields and survey surface composition. A special task is to search for ice that might be hidden in permanently shadowed regions near the poles; such ice would provide a source of water for future visitors to the Moon.
Maps of the Moon based on the Clementine mission are now available. One interesting feature that it newly shows is a huge crater, now called the South Pole-Aitken Crater, that is 13 km deep and 2500 km across. Covering about a quarter of the Moon's circumference, it is the largest and deepest solar-system crater. It may have come from a huge impact about 4 billion years ago and would be the oldest lunar feature.
Please see the article by Maria Zuber of Goddard Space Flight
Center in Science for December 16, 1994, which contained
several articles about the mission and its results. You can access the
Naval Research Laboratory's Clementine
homepage and get access to 1.8 million Clementine images over the
Web.
Also, G. Jeffrey Taylor's Scientific American article, "The Scientific
Legacy of Apollo," July 1994, pp. 40-47, is an excellent summary.