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

	
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