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Discovery ProgramAll Discovery missions by definition don't transport humans into space
-- a feature that not only keeps expenses down but also permits higher-risk
projects. Unlike previous NASA-sponsored space exploration, the Discovery
program does not have a specific agenda with regard to scientific topic.
Approximately every year and a half, requests for proposals are issued
by NASA -- the program goal is to launch one Discovery mission per year.
Proposals are reviewed based on several criteria, including scientific
content, technological innovation, economy of the proposed mission development
and execution, and public awareness/educational outreach possibilities.
Thus, the quality of the overall proposal in conjunction with subject determines
what will be funded -- whether it be planets, comets, asteroids or deep
space.
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To
date, current Discovery missions -- either in progress or still in the
development stages -- are set to explore Mars, asteroid 433 Eros, the Moon
and the exterior of an active comet. The next Discovery mission has just
been selected from a group of proposals spanning a wide range of scientific
objectives. The final search was narrowed to five potential missions: Messenger
(a Mercury orbiter), Vesat (a Venus orbiter), Aladdin (sample return from
martian moons Phobos and Deimos), Contour (a comet fly-by), and Genesis
(solar wind sample return). Genesis and Contour were selected. The next
request for proposals will be distributed soon, with selection targeted
for the spring of 1998.
Lunar
Prospector is a free-flier that will not land on the the surface of
the Moon. It was launched on Jan. 6, 1998 and, on Jan. 11, 1998, was successfully
placed into a lunar polar orbit 63 miles above the Moon's surface. The
spacecraft and its instruments will conduct studies of the Moon for a period
of one year. It will remain in orbit until the spacecraft runs out of fuel
and impacts the surface of the Moon. A small, spin-stabilized spacecraft
that uses flight-qualified, modern technologies and instrumentation, Prospector
will ensure results while minimizing risk. Prospector is simply designed
-- it is a small graphite-epoxy drum with surface-mounted solar cells and
three 8-foot masts which carry its instruments and isolate them from the
main body of the spacecraft. Lunar Prospector will map the elemental composition,
the gravity and magnetic fields, and resources of the Moon. It will provide
insights into lunar origin and evolution. Finally, Prospector will definitively
determine whether or not water ice is present in the Moon's polar regions.
Prospector's 22-month development period demonstrates a streamlined process
of developing a spacecraft and is a model of private industry/government
cooperation.
Near
(Near Earth Asteroid Rendezvous), NASA's first Discovery Mission, operated
by the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland,
will be the first spacecraft to orbit an asteroid. It is designed to provide
scientists with data to answer fundamental questions about near-earth objects
such as asteroids and comets. Near will rendezvous with asteroid 433 Eros
on February 6,1999.
Stardust,
NASA's fourth Discovery mission, is operated by the Jet Propulsion Laboratory
of the California Institute of Technology in Pasadena, California. Stardust
is scheduled for launch in early 1999. The primary aims of the Stardust
mission are to gather dust grains between stars and to collect samples
of material surrounding an active comet. Such information will help scientists
understand more about the nature and history of the Solar System.