Nov. 21, 2006
Erica Hupp/Dwayne Brown
Headquarters, Washington
202-358-1237/1726
Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
RELEASE: 06-357
NASA'S MARS GLOBAL SURVEYOR MAY BE AT MISSION'S END
Pasadena, Calif. -- NASA's Mars Global Surveyor has likely finished
its operating career. The spacecraft has served the longest and been
the most productive of any mission ever sent to the red planet.
"Mars Global Surveyor has surpassed all expectations," said Michael
Meyer, NASA's lead scientist for Mars exploration at NASA
Headquarters, Washington. "It has already been the most productive
science mission to Mars, and it will yield more discoveries as the
treasury of observations it has made continues to be analyzed for
years to come." Its camera has returned more than 240,000 images to
Earth.
The orbiter has not communicated with Earth since Nov. 2. Preliminary
indications are that a solar panel became difficult to pivot, raising
the possibility that the spacecraft may no longer be able to generate
enough power to communicate. Engineers are also exploring other
possible explanations for the radio silence.
"Realistically, we have run through the most likely possibilities for
re-establishing communication, and we are facing the likelihood that
the amazing flow of scientific observations from Mars Global Surveyor
is over," said Fuk Li, Mars Exploration Program manager at NASA's Jet
Propulsion Laboratory (JPL), Pasadena, Calif. "We are not giving up
hope, though."
Efforts to regain contact with the spacecraft and determine what has
happened to it will continue. NASA's newest Mars spacecraft, the Mars
Reconnaissance Orbiter, pointed its cameras towards Mars Global
Surveyor on Monday. "We have looked for Mars Global Surveyor with the
star tracker, the context camera and the high-resolution camera on
Mars Reconnaissance Orbiter," said Doug McCuistion, Mars Exploration
Program director at NASA Headquarters. "Preliminary analysis of the
images did not show any definitive sightings of a spacecraft."
The next possibility for learning more about Mars Global Surveyor's
status is a plan to send it a command to use a transmitter that could
be heard by one of NASA's Mars Exploration Rovers later this week.
Mars Global Surveyor launched on Nov. 7, 1996, and began orbiting Mars
on Sept. 11, 1997. It pioneered the use of aerobraking at Mars, using
careful dips into the atmosphere for friction to shrink a long
elliptical orbit into a nearly circular one. The mission then started
its primary mapping phase in April 1999. The original plan was to
examine the planet for one Mars year, nearly two Earth years. Based
on the value of the science returned by the spacecraft, NASA extended
its mission four times.
"It is an extraordinary machine that has done things the designers
never envisioned despite a broken wing, a failed gyro and a worn-out
reaction wheel. The builders and operating staff can be proud of
their legacy of scientific discoveries and key support for subsequent
missions," said Tom Thorpe, project manager for Mars Global Surveyor
at JPL.
The spacecraft evaluated landing sites for the twin NASA rovers that
landed in 2004 and sites for future landings of the Phoenix and Mars
Science Laboratory missions. It monitored atmospheric conditions
during aerobraking by newer orbiters. It served as a relay link for
the rovers and provided mapping information about their surroundings.
"When we watched the launch 10 years ago, we wondered if we would make
the specified mission length. We certainly were not thinking of a
10-year operating life," said JPL retiree Glenn Cunningham, who
managed the Global Surveyor project through development and launch.
A few of the mission's many important discoveries about Mars include:
-- The spacecraft's camera found gullies cut into many slopes that
have few, if any, impact craters. This indicates the gullies are
geologically young. Scientists interpret this as evidence of action
by liquid water, essentially in modern times.
-- The mineral-mapping infrared spectrometer found concentrations of a
mineral that often forms under wet conditions, fine-grained hematite.
This discovery led to selection of a hematite-rich region as the
landing site for NASA's Mars Exploration Rover Opportunity.
-- Laser altimeter measurements have produced an unprecedented global
topographic map of Mars. The instrument revealed a multitude of
highly eroded or buried craters too subtle for previous observation,
and mapped canyons within the polar ice caps.
-- The magnetometer found localized remnant magnetic fields,
indicating that Mars once had a global magnetic field like Earth's,
shielding the surface from deadly cosmic rays.
-- The camera found a fan-shaped area of interweaving, curved ridges
interpreted as evidence of an ancient river delta resulting from
persistent flow of water over an extended period in the planet's
ancient past.
-- A long life allowed Global Surveyor to track changes through
repeated annual cycles. For three Martian summers in a row, deposits
of carbon-dioxide ice near Mars' South Pole shrunk from the previous
year's size, suggesting a climate change in progress.
JPL manages Mars Global Surveyor for the NASA Science Mission
Directorate, Washington.
For more information on the mission, visit the Internet at:
http://www.nasa.gov/mission_pages/mgs/index.html
