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SCIENCE FRIDAY ON MARS
THE PATHFINDER MISSION
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One hour before our broadcast begins, if all goes as planned, the
Mars Pathfinder spacecraft will have landed on Mars. The
international space community has its attention focused on the
headquarters of the Jet Propulsion Laboratory in Pasedena,
California, where scientists are waiting the first reports from the
probe -- the first to land on Mars since the Viking landers of 1976.
The mission intends to land a probe on the surface of Mars. The
lander, Pathfinder, will target an area at the mouth of an ancient
flood channel called Ares Vallis. Located at 19.5 deg. N. lat, 32.8
deg W, the site is thought to be strewn with rocks for sampling, but
flat enough to safely land. The site was chosen because of the
possibility that water ran here once. In addition, the low elevation
of the site and the good solar exposure are favorable conditions for
a successful landing.
The Pathfinder will enter the atmosphere at over 16,000 mph. After
braking through the thin Martian atmosphere, protected by a heat
shielding "aeroshell", the lander will parachute towards the surface.
After the parachute opens, the aeroshell will fall away.
The parachute will carry the lander through much of the atmosphere,
but not all the way. The lander will be slowly lowered from the
parachute by a tether and braked additionally by three small rockets.
About 65 feet above the surface, airbags surrounding the craft will
inflate, the tether will be cut, and the lander will bounce to the
ground, surrounded by its airbags.
Once the lander bounces to a stop, the airbags will deflate, the
lander will right itself, and solar panels will open like the petals
of a flower. The lander will take pictures of the surface, deploy the
Mars Sojurner Rover, and report back to Earth.
The lightweight Sojurner, about the size of a laser printer, will
explore the surface of the nearby ancient flood plain. It will
operate with a certain degree of autonomy -- mission controllers will
tell it where to go, then Sojurner will figure out how to get there.
Pathfinder will continue to image the surface, monitor the atmosphere
and weather, and provide a communications link for Sojurner. Sojurner
is equipped with cameras, a laser navigating system, and an alpha
proton x-ray spectrometer that will allow it to analyze rocks and
soil samples that it comes into contact with.
Pathfinder At-A-Glance
- launched December 5, 1996
- launch vehicle: Delta II rocket
- arrives Mars July 4, 1997
- cost: $196 million ($171M for lander, $25M for rover)
- weight : about 870 kg (lander: about 11.5 kg)
- planned time of operation: 30 days, though much longer is
hoped for
All photos and drawings this page are
copyrighted and are used courtesy of NASA and the Jet Propulsion
Laboratory
.
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