PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
Contact: Diane Ainsworth
FOR IMMEDIATE RELEASE
August 8, 1997
MARS PATHFINDER CONCLUDES PRIMARY SCIENCE MISSION
NASA's Mars Pathfinder spacecraft -- a novel mission to send
an inexpensive lander and roving prospector to the surface of
Mars - has concluded its primary mission, fulfilling all of its
objectives and returning a wealth of new information about the
red planet.
The robotic lander, which continues to explore an ancient
outflow channel in Mars' northern hemisphere, completed its
milestone 30-day mission Aug. 3, capturing far more data on the
atmosphere, weather and geology of Mars than scientists expected.
In all, Pathfinder returned 1.2 gigabits (1.2 billion bits) of
data and 9,669 tantalizing pictures of the Martian landscape.
"The data returned by the Sagan Memorial Station and
Sojourner has been nothing short of spectacular, and it will help
provide a scientific basis for future Mars missions, including a
sample return, for years to come," said Dr. Wesley Huntress, NASA
associate administrator for space science. "The Pathfinder
team's 'can do' attitude not only was critical to overcoming
several complex technical challenges during development and
cruise, but has carried through the uncharted territory of
operating a solar-powered lander and mobile rover on the surface
of a planet millions of miles from Earth."
"This mission demonstrated a reliable and low-cost system
for placing science payloads on the surface of Mars," said Brian
Muirhead, Mars Pathfinder project manager at NASA's Jet
Propulsion Laboratory. "We've validated NASA's commitment to
low-cost planetary exploration, shown the usefulness of sending
microrovers to explore Mars, and obtained significant science
data to help understand the structure and meteorology of the
Martian atmosphere, and to understand the composition of the
Martian rocks and soil."
A new portrait of the Martian environment has begun to
emerge in the 30 days since Pathfinder and its small, 10.5-
kilogram (23-pound) rover began to record weather patterns,
atmospheric opacity and the chemical composition of rocks washed
down into the Ares Vallis flood plain. The rover's alpha proton
X-ray spectrometer, led by Principal Investigator Dr. Rudolph
Rieder, was responsible for making the first in-situ measurements
of rocks near the landing site.
"We are seeing much more differentiation of volcanics than
we expected to see," said Dr. Matthew Golombek, Mars Pathfinder
project scientist at JPL. "The high silica content of one of the
rocks we've measured suggests that there was more crustal
activity - heating and recycling of materials -- early in Mars'
history than we thought."
Similarly, atmospheric-surface interactions, measured by a
meteorology package onboard the lander, are confirming some
conditions observed by the Viking landers 21 years ago, while
raising questions about other aspects of the planet's global
system of transporting volatiles such as water vapor,
clouds and dust, said Science Team Leader Dr. Timothy Schofield.
The meteorology mast on the lander has observed a rapid drop-off in temperatures
just a few feet above the surface, and one detailed 24-hour measurement set revealed
temperature fluctuations of 30-40 degrees Fahrenheit in a matter of minutes.
In addition, sweeping, color panoramas of the Martian
landscape, created by the Imager for Mars Pathfinder (IMP) team
and Principal Investigator Peter Smith, are revealing clear
evidence that the surface of Mars has been altered by winds and
flowing water.
Sojourner, a robust rover capable of semi-autonomous
"behaviors," captured the imagination of the public, which
followed the mission with great interest via the World Wide Web.
Twenty Pathfinder mirror sites, constructed by JPL web engineer
Kirk Goodall and managed by Pathfinder webmaster David Dubov,
recorded 565,902,373 hits worldwide during the period of July 1 -
August 4. The highest volume of hits in one day occurred on July
8, when a record 47 million hits were logged, which is more than
twice the volume of hits received on any one day during the 1996
Olympic Games in Atlanta.
The rover's performance has easily surpassed its designers'
minimum expectations. Engineers designed the roving vehicle's
electronics, battery power and hazard avoidance features to see
it through at least a week of safe roving, not knowing beforehand
what conditions it might encounter on Mars. After 30 days, the
rover is still healthy and has clocked 52 meters (171 feet)
distance, circumnavigated the lander and taken 384 spectacular
views of rocks and the lander.
"Sojourner's capabilities to detect hazards and then act on
its own to overcome those hazards has been remarkable," said Dr.
Jacob Matijevic, Sojourner project manager. "The technology
experiments we have been able to perform with the rover's wheels
have given us more information about the composition of the
Martian soil, as well as rocks around the landing site.
Sojourner's durability in this frigid, hostile environment is
also showing us that we are on the right track to building
smarter, even more durable rovers for future missions."
Pathfinder's primary objective was to demonstrate a low-cost
way of delivering an instrumented lander and free-ranging rover
to the surface of the red planet. Landers and rovers of the
future will share the heritage of spacecraft designs and
technologies tested in this "pathfinding" mission.
Part of NASA's Discovery program of low-cost planetary
missions with highly focused science goals, the spacecraft used
an innovative method of directly entering the Martian atmosphere.
Assisted by an 11-meter (36-foot) diameter parachute, the
spacecraft descended to the surface of Mars and landed, using
airbags to cushion the impact.
This novel method of diving into the Martian atmosphere
worked like a charm. "Every event during the entry, descent and
landing (EDL) went almost perfectly," said Richard Cook,
Pathfinder mission manager. "The sequences were executed right on
time and well within our margins."
Pathfinder landed right on the money, within 20 kilometers
(13 miles) of the targeted landing site. The landing site
coordinates in Ares Vallis were later identified as 19.33 degrees
north latitude, 33.55 degrees west longitude.
The spacecraft's terminal velocity as it parachuted to the
ground was higher than expected, said Rob Manning, Pathfinder
flight system chief engineer. "Interestingly, we estimated our
descent on the parachute at about 60 meters per second (134 miles
per hour). Software controlling the retro rockets recorded
Pathfinder's speed at about 61.5 meters per second (140 miles per
hour) at the time the RAD (rocket-assisted deceleration) rockets
fired."
Pathfinder's performance in the Martian atmosphere will be
of great value to Mars Global Surveyor, which will aerobrake
through the Martian atmosphere to circularize its orbit when it
reaches Mars on Sept. 11. The Pathfinder navigation team, led by
Pieter Kallemyn of JPL, estimated horizontal wind velocities in
the upper atmosphere, which accelerated the spacecraft's descent
velocity by about 13 meters per second (20 to 25 miles per hour).
After being suspended from a 20-meter (65-foot) bridle and
firing its retro rockets, a 5.8-meter (19-foot) diameter cluster
of airbags softened Pathfinder's landing, marking the first time
this airbag technique has been used. The spacecraft hit the
ground at a speed of about 18 meters per second (40 miles per
hour) and bounced about 16 times across the landscape before
coming to a halt. The airbag seems to have performed perfectly
and sustained little or no damage. To top it off, the spacecraft
even landed on its base petal, consequently allowing its thumb-
sized antenna to communicate the successful landing to a jubilant
team on Earth only three minutes after touch down.
Science data from the surface of Mars will continue to be
collected and transmitted to Earth, then analyzed by scientists,
as Pathfinder enters its extended mission. The lander was placed
in a two-day hybernation period to recharge its battery after the
conclusion of the primary mission, and the flight team will begin
to power the lander battery off each Martian night now to
conserve energy. The rover's batteries remain in good condition,
but are not rechargeable.
The Mars Pathfinder mission is managed by the Jet Propulsion
Laboratory for NASA's Office of Space Science, Washington, D.C.
JPL is a division of the California Institute of Technology,
Pasadena, CA.
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