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Fwd: news release - LUNAR PROSPECTOR SET TO MAKE SCIENCE "SPLASH"

Thought some people here might be interested.

Mike
---------------------------------------------

June 2, 1999
David Morse
NASA Ames Research Center, Moffett Field, CA
(Phone:  650/604-4724)
dmorse@mail.arc.nasa.gov

RELEASE:  99-36AR

LUNAR PROSPECTOR SET TO MAKE SCIENCE "SPLASH"

The mission of NASA's Lunar Prospector will end on July 31, 1999, when
ground controllers attempt to direct the spacecraft to impact the surface
of the Moon inside a permanently shadowed crater near the lunar south pole.

This effort to gain additional science data about the Moon's composition
was proposed to NASA by an external team of scientists led by Dr. David
Goldstein of the University of Texas in Austin.  Although the Lunar
Prospector spacecraft will weigh only 354 pounds (161 kilograms) at mission
end, the energy at impact will be the equivalent of crashing a two-ton car
at more than 1,100 miles per hour.

Scientists hope that the direct impact into a lunar crater will liberate up
to 40 pounds of water vapor that may be detectable from ground- and
space-based observatories. A positive detection of water vapor or its
byproduct, OH, would provide definitive proof of what some scientists have
long suspected -- the presence of water ice in the lunar polar regions.

"While the probability of success for such a bold undertaking is low, the
potential science payoff is tremendous," said Dr. Guenter Riegler, Director
of the Research Program Management Division in the Office of Space Science
at NASA Headquarters, Washington, DC.

"External peer reviews of this plan have been very favorable, and we have
concluded that it is both technically and operationally feasible," Riegler
said.  "Since the implementation costs are minimal and the mission is
scheduled to end anyway, it seems fitting to give Lunar Prospector the
chance to provide scientific data right up to the very end of its highly
successful mission."

Lunar Prospector was launched on Jan. 6, 1998, with a one-year primary and
six-month extended mission to explore the lunar surface remotely. In March
1998, mission scientists announced that science instruments aboard Lunar
Prospector had detected sufficiently large quantities of hydrogen at the
lunar poles to infer the presence of water ice. In September, scientists
estimated that up to six billion metric tons of water ice may be buried in
the permanently shadowed craters of the Moon's poles.

-more-

-2-

The current plan calls for a controlled impact of the Lunar Prospector
spacecraft in the early morning hours of July 31 directly into the Mawson
crater, located at the southern lunar pole. This crater is ideal for the
proposed experiment. It is only 31 to 38 miles (50 to 60 kilometers) across
and has a rim which is high enough to provide a permanent shadow, yet it is
low enough to provide for a suitable spacecraft impact trajectory. Data
from other observations suggest that the crater could contain a high
concentration of water ice. Finally, the crater is observable at impact
time from Earth-based observatories and orbiting platforms.

"A positive spectral detection of water vapor or its photo-dissociated
byproduct, OH, would provide definite proof of the presence of water ice in
the lunar regolith," Goldstein said. However, scientists warn that the
failure to observe the desired signal does not mean that water ice is not
present. The model could be wrong, the spacecraft may not impact the
desired region or the impact energy may be insufficient to liberate an
observable plume of water vapor or OH. The overall probability of success
is estimated to be about 10 percent.

Observing time has been granted at the University of Texas McDonald
Observatory and on the Hubble Space Telescope. It is also being sought at
other sites from which the Moon is clearly visible in the early morning
hours of July 31.

Goldstein and his team will present a detailed description of their
proposal in the June 15 issue of "Geophysical Research Letters."

Further information about Lunar Prospector can be obtained at the project
website at:
			http://lunar.arc.nasa.gov

Lunar Prospector was the first of NASA's Discovery class of "faster,
better, cheaper" space exploration missions. The $63 million mission is
managed by NASA Ames Research Center, Moffett Field, CA.


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