July 14, 1999. Copyright 1999. Graphic News. All rights reserved.

SEARCH FOR MOON WATER

LONDON, July 14, Graphic News: NASA PLANS to crash an orbiting spacecraft onto the lunar south pole in an attempt to establish whether water exists on the moonÕs surface. Scientists hope that the July 31 impact will send up a plume of water vapour detectable by ground-based observatories and the Hubble Space Telescope.
Last year, NASAÕs Lunar Prospector orbiter Ð a $65 million robot craft launched in January 1998 Ð detected what seemed to be large deposits of hydrogen at the moonÕs north and south poles. Scientists said this suggested the presence of water ice.
ÒWe are certain there is water there,Ó said Alan Binder, the missionÕs principal investigator. ÒWe think we are seeing between 10 million and 100 million tons of water.Ó
If correct there could be enough water ice in the loose soil of the moon to support a lunar base and perhaps one day to build a human colony there.
The water is believed to be frozen and mixed with shaded soil deep in scattered craters near the north and south lunar poles. Binder believes it would be easy to convert it to liquid water that could be used to make hydrogen rocket propellant and oxygen for breathing.
The Lunar Prospector used an instrument called a neutron spectrometer to scan for small particles of energy, called neutrons, which emanate continually from the lunar surface. 
The key to finding evidence of water is how neutrons interact with the lunar soil. ÒWetÓ soil contains an abundance of hydrogen ions which slow down medium-energy and high-energy ÒfastÓ neutrons. Collisions between the hydrogen ions and neutrons resemble ping-pong balls bumping into each other Ð after the collision, each neutron loses energy and travels more slowly. 
Researchers at Cornell University in New York and NASAÕs Jet Propulsion Laboratory in California found that dips in medium-energy neutrons occured at both lunar poles
It is believed the moon was dry when it first formed some four billion years ago. Any water deposited by comets and asteroid impacts would evaporate into space due to the high daytime surface temperature.
But there are deep craters that are often fully or partly in shadow all of the time. Such areas are called Òcold trapsÓ, where the temperature stays at around minus 280 degrees Fahrenheit (minus 140 degrees Centigrade).
The researchers found about 1,000 square miles (2,650 square km) of shadowed area at the north pole and 2,000 square miles (5,100 square km) at the south pole.
Lunar Prospector is part of NASAÕs recently implemented Discovery program, developed to produce frequent, low-cost missions to explore the Solar System. The spacecraft was built from Òoff-the-shelf,Ó flight-proven hardware in only 22 months.
In addition to the search for hydrogen, ProspectorÕs other missions included gamma ray analysis to determine concentrations of elements such as uranium and iron on the lunar surface, and an alpha particle spectrometer which looked for indications of volcanic and tectonic activity.
The ProspectorÕs instruments also measured the moonÕs magnetic and gravitational fields producing new data supporting the ÒcollisionÓ theory Ð that the moon was ripped away from Earth following a massive interplanetary collision very early in its history.
One minor controversy surrounding the mission has involved a nonscientific payload aboard Prospector: one ounce (28 grams) of the ashes of planetary scientist Gene Shoemaker, who died last year.
Navajo Indian officials have objected to the inclusion of human remains on Prospector, saying human bodies should not be left on the moon, which they regard as sacred ground. NASA officials have apologized for any misunderstanding over the ashes which were not intended to cause insult to anyone.
/ENDS