Lunar Prospector, the third Discovery mission, launched on January 6, 1998, and was successfully placed into orbit 63 miles above the lunar surface five days later. MISSION OBJECTIVES The studies conducted by the spacecraft and its five instruments were designed to provide insights into lunar origin and evolution and determine whether or not water ice is present in the Moon's polar regions.
Besides water, Lunar Prospector searched for other natural resources, such as minerals and gases, that could be used to build and sustain a future human lunar base or to manufacture fuel for launching spacecraft from the Moon to the rest of the Solar System.
MISSION RESULTS
The science data returned from Lunar Prospector has enabled scientists to create the most complete and detailed maps of the gravity, magnetic properties and chemical composition of the Moon's entire surface.
While the Moon's magnetic field is relatively weak, Prospector detected large localized magnetic fields that create the two smallest magnetospheres in the Solar System.
DOES WATER EXIST? In March 1998, mission scientists announced tentative findings of the presence of water ice in shadowed
craters near the Moon's south and north poles, based on reasonable scientific assumptions from the levels of
hydrogen detected, from which water ice is inferred. They estimated that up to six billion metric tons of water
ice may be buried in these craters under about 18 inches of soil.
The mission originally was scheduled to end sometime in July 1999, when it would run out of fuel and randomly impact
the lunar surface. However, in a dramatic attempt to find proof of water ice, scientists came up with an innovative
plan to direct the spacecraft to impact the surface of the Moon inside a permanently shadowed crater near the lunar
south pole. The concept was that the impact could free up to 40 pounds of water vapor that may be detectable from ground
and space based observatories. A positive detection of water vapor would provide definitive proof of the presence of water
ice in the lunar polar regions.
On July 31, 1999, the Mission Control team successfully ended the mission at 2:52 a.m. PDT when the spacecraft slammed into
its intended target. The controlled crash produced no observable signature of water, according to data from Earth-based
observatories and spacecraft such as the Hubble Space Telescope. This lack of evidence leaves open the question of whether
ancient cometary impacts left ice that is buried in permanently shadowed regions of the Moon.
Failure to prove that water ice exists in the lunar polar regions does not suggest that it is absent, but rather that this
experiment, acknowledged as high payoff but with low probability of success, has not provided the conclusive evidence that
was being sought. Overall, the mission provided a tremendous volume of valuable data that scientists will be analyzing for
years to come. MISSION MANAGEMENT The Lunar Prospector mission was managed by NASA's Ames Research Center. Dr. Alan
Binder of the Lunar Research Institute was the Principal Investigator. The mission
was implemented by Lockheed Martin Missiles and Space, Sunnyvale, California.
For complete information on the mission and the largest collection of lunar media anywhere in the world, visit the Lunar Prospector home page.
