Douglas Isbell
Headquarters, Washington, DC            November 22, 1995
(Phone: 202/358-1753)

RELEASE:  95-209

COMET SAMPLE RETURN MISSION PICKED AS NEXT DISCOVERY FLIGHT

     A spacecraft designed to gather samples of dust spewed
from a comet and return the dust to Earth for detailed
analysis has been selected to become the fourth flight
mission in NASA's Discovery program.

     Known as Stardust, the mission also will gather and
return samples of interstellar dust that the spacecraft
encounters during its trip through the Solar System to fly
by a comet called Wild-2 in January 2004.  Stardust was one
of three Discovery mission proposals selected for further
study as part of a February 1995 announcement by NASA that a
Moon-orbiting mission called Lunar Prospector had been
selected as the third Discovery flight.

     "Stardust was rated highest in terms of scientific
content and, when combined with its low cost and high
probability of success, this translates into the best return
on investment for the nation," said Dr. Wesley T. Huntress
Jr., NASA Associate Administrator for Space Science.  "The
Stardust team also did an excellent job of updating their
plan to communicate the purpose and results of this exciting
mission to educators and the public."

     The Stardust mission team is led by Principal
Investigator Dr. Donald Brownlee of the University of
Washington in Seattle, with Lockheed-Martin Astronautics,
Denver, as the contractor building the spacecraft.  NASA's
Jet Propulsion Laboratory, Pasadena, CA, will provide
project management.

     Comet Wild-2 is known as a "fresh comet" because its
orbit was deflected from much farther out in the Solar
System by the gravitational attraction of Jupiter in 1974.
Stardust will approach as close as 62 miles to the comet's nucleus.

     "Space scientists are intensely interested in comets
because we believe that most of them are well-preserved
remnants from the earliest days of star and planetary
formation," Huntress said.  "Stardust should also give us
some unique guidance about how to focus the science we plan
to conduct a few years later with a surface lander on a
different comet during the international Rosetta mission."

     Stardust will be launched on an expendable launch
vehicle in February 1999 for a total mission cost to NASA in
real-year dollars of $199.6 million.  The return capsule
carrying the dust samples would parachute to Earth for
landing on a dry Utah lake bed in January 2006.

     Stardust will use an unusual material called aerogel to
capture the dust samples.  This porous, extremely low
density material is somewhat like glass in that it is made
of silica -- a pure form of sand -- and it has about the
same melting point.  Although aerogel does not absorb
moisture, the strangely fluorescent substance can absorb
large amounts of gas or particle matter due to its
remarkable internal surface area.

     The spacecraft also will carry an optical camera that
should return cometary images with 10 times the clarity of
those taken of Halley's Comet by previous space missions, as
well as a mass spectrometer provided by Germany to perform
basic compositional analysis of the samples while in-flight.

     Stardust was selected over a proposed mission to study
the circulation of the atmosphere of Venus, known as the
Venus Multiprobe, and a proposed mission to collect samples
of particle matter from the Sun, called Suess-Urey.  These
three missions and Lunar Prospector were among 28 Discovery
proposals submitted to NASA in October 1994 in response to
an August 1994 announcement of opportunity.

     The first two missions in the Discovery program will be
launched in 1996, in February and December, respectively:
the Near Earth Asteroid Rendezvous, a small spacecraft that
will orbit and study the asteroid Eros beginning in January
1999; and, the Mars Pathfinder, designed to place a small
lander and robotic rover on the surface of Mars in July 1997.

     Formally started in NASA's FY 1994 budget, the
Discovery program features small planetary exploration
spacecraft with focused science goals that can be built in
36 months or less, for less than $150 million, not including
cost of launch vehicle.  The program grew out of a series of
discussions and workshops that NASA has held with the space
science community.

                    -end-

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