Mathilde preserves carbon-rich ma-
terial from the early solar system.
NEAR became the first spacecraft to
orbit an asteroid in January, 2000,
when it arrived at the asteroid Eros.
The Mars Pathfinder was the sec-
ond project of the Discovery pro-
gram. The Pathfinder landed on
Mars on July 4, 1997, deploying the
10-kilogram (22-pound) Sojourner
rover, which analyzed rocks and
soils, while the Pathfinder moni-
tored weather. The results suggest
that in its past Mars had been
warmer and wetter and had a
thicker atmosphere.
The Mars Global Surveyor,
launched on November 7, 1996, was
the first of a series of Mars missions
planned for launching every twenty-
six months for a decade. Mars
Global Surveyor mapped the sur-
face and the gravitational and mag-
netic fields. Scientists found that
water may still flow sporadically on the Martian sur-
face.
Lunar Prospector was the third Discovery mis-
sion. It was launched on January 6, 1998, and began
orbiting 101 kilometers (63 miles) above the Moon’s
surface five days later. Prospector provided detailed
maps of the gravity, magnetic properties, and chemi-
cal composition of the Moon’s entire surface and
found evidence for water ice in shadowed craters
near its poles.
Deep Space 1, the first of NASA’s New Millen-
nium spacecraft designed to test advanced, high-risk
technologies, was launched on October 24, 1998. It
demonstrated advanced solar-electric propulsion
and an autonomous navigation system, the first arti-
ficial intelligence system to control a spacecraft with-
out human supervision. Its three-year mission took it
past the asteroid Braille and comet Borrelly, provid-
ing the best images of a comet up to that time.
Impact Joint missions to Mir allowed NASA and the
Russian Federal Space Agency to cooperate as inter-
national partners, preparing for the assembly of the
International Space Station. The Discovery pro-
gram demonstrated that “smaller, faster, cheaper”
spacecraft can produce important results, while the
success of large observatories reshaped views of the
solar system and the universe.Further Reading
Grinspoon, David.Venus Revealed: A New Look Below
the Clouds of Our Mysterious Twin Planet. New York:
Perseus Books, 1997. Explains the advances in un-
derstanding of Venus from the Magellan observa-
tions.
Harland, David.Jupiter Odyssey: The Stor y of NASA’s
Galileo Mission. New York: Springer-Praxis, 2000.
A 447-page account of the quarter-century from
the conception to the flight and discoveries of the
Galileo spacecraft.
Mishkin, Andrew.Sojourner: An Insider’s View of the
Mars Pathfinder Mission. New York: Berkley Books,- A well-illustrated, firsthand account of the
Mars Pathfinder probe by a systems engineer at
NASA’s Jet Propulsion Laboratory ( JPL).
George J. Flynn
See also Astronomy; Bondar, Roberta; Glenn,
John; Hale-Bopp comet; Hubble Space Telescope;
Lucid, Shannon; Mars exploration; Science and tech-
nology; Shoemaker-Levy 9 comet; Space shuttle pro-
gram.794 Space exploration The Nineties in America
An artist’s conception of the Galileo spacecraft during its encounter with Io, a volcanic
moon of Jupiter.(NASA)