PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
Contact: Diane Ainsworth
FOR IMMEDIATE RELEASE
January 31, 1996
MARS PATHFINDER LANDER AND ROVER FULLY INTEGRATED
Heading into the home stretch of spacecraft assembly, NASA's
Mars Pathfinder lander -- a tetrahedral-shaped spacecraft
weighing 351 kilograms (772 pounds) and standing about 1 meter
(3.2 feet) tall -- was mated today with its companion rover,
Sojourner, just as it will fly to Mars later this year.
The lander and rover, in development at NASA's Jet
Propulsion Laboratory, crossed a major engineering milestone with
full integration after a year of rigorous testing of components
making up the spacecraft's landing gear, said Brian Muirhead,
Pathfinder flight system manager. Subsystems included a
parachute, measuring 12.7 meters (41 feet) in diameter, three
small, rocket-assisted deceleration thrusters to help the
spacecraft brake through the Martian atmosphere, and giant,
multi-lobed air bags to cushion its landing.
Now with its rover mounted and secured by cables to an
inside petal, Pathfinder will be folded up to undergo integration
testing in the next several days, Muirhead said. In the weeks
ahead, the spacecraft will next be attached to the inside of its
backshell and then be encased in a Viking-derived heatshield.
"This is actually the first and last time that we will see
Pathfinder and Sojourner completely assembled until just before
launch," Muirhead said. "It's exciting to see the spacecraft in
full flight configuration, and to know that we have set a new
standard for JPL and the world in the development of
interplanetary spacecraft."
Currently residing in JPL's spacecraft assembly clean room,
Pathfinder will be delivered to JPL's 25-foot space simulator in
March for spin-balance, acoustic and thermal vacuum testing,
added Robert Manning, flight system chief engineer. Over the
summer, the spacecraft will be taken apart again for final pyro
and electrical testing before its components are prepared for
shipping on Sept. 1 to Cape Canaveral, Fla.
Pathfinder is designed to place a low-cost delivery system
on the surface of Mars, demonstrating a new and unconventional
atmospheric entry and landing approach. The spacecraft will be
launched on Dec. 2 from Cape Canaveral, Fla., and spend seven
months cruising to Mars. Landing on an ancient flood basin known
as Ares Vallis, Pathfinder will touch down on July 4, 1997.
Twenty-four hours before Mars arrival, the spacecraft will
turn approximately 7 degrees to its entry attitude and continue
to descend, Manning said. Hitting the thin upper atmosphere at
more than 27,000 kilometers per hour (about 17,000 miles per
hour), the lander's heat shield will slow the craft to about
1,450 kilometers per hour (900 miles per hour) in about two
minutes. An onboard computer will sense the slow-down in speed
and eject a large parachute.
Seconds later, the heat shield, still red hot from the heat
of entry, will be released and the lander will be separated from
the backshell on a bridle. Because the rarefied atmosphere of
Mars is only 1/100th as dense as Earth's, the parachute will slow
the lander to about 250 kilometers per hour (155 miles per hour).
A few seconds before impact, a giant cocoon of air bags will be
inflated and the rockets will fire to literally stop the lander
in mid-air and slow it to less than 72 kilometers per hour (45
miles per hour).
Landing four hours before sunrise, Pathfinder will bounce
along the Martian surface like a huge beach ball before coming to
a halt. The craft will spend the next three hours deflating and
retracting its air bags, standing itself upright and unfolding
its petals to expose the 10-kilogram (22-pound) Sojourner rover.
Daylight will give Sojourner the solar power it will need to
power up, rise to its full height and drive off one of the two
exit ramps onto the Martian surface.
Although Pathfinder is considered an engineering
demonstration, it will accomplish a focused set of science
investigations with a stereo, multi-colored lander imager,
atmospheric instruments that will be used as a weather station
after landing, and an autonomous rover capable of measuring the
composition of rocks and surface materials near the landing site.
Sojourner will also perform mobility tests and image its
surroundings. One of its first jobs will be to image the lander,
so that scientists and engineers can determine the lander's
condition and study the local terrain.
The Pathfinder lander will carry out most of its engineering
objectives within the first few hours after landing, then be used
to take panoramic images of the Martian landscape and support
rover activities. The lander, the first in NASA's Discovery
program of low-cost planetary spacecraft with highly focused
science goals, has a mission lifetime of at least 30 days.
Sojourner is expected to rove the surface of Mars for a minimum
of seven days.
The Mars Pathfinder mission is managed by the Jet Propulsion
Laboratory for NASA's Office of Space Science, Washington, D.C.
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