[meteorite-list] Orbiter's Long Life Helps Scientists Track Changes on Mars

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Sep 20 17:17:05 2005
Message-ID: <200509202115.j8KLFqM25431_at_zagami.jpl.nasa.gov>

MEDIA RELATIONS 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

Guy Webster (818) 354-6278
Jet Propulsion Laboratory, Pasadena, Calif.

Dolores Beasley (202) 358-1753
NASA Headquarters, Washington

News Release: 2005-152 September 20, 2005

Orbiter's Long Life Helps Scientists Track Changes on Mars

New gullies that did not exist in mid-2002 have appeared
on a Martian sand dune.

That's just one of the surprising discoveries that have
resulted from the extended life of NASA's Mars Global
Surveyor, which this month began its ninth year in orbit
around Mars. Boulders tumbling down a Martian slope left
tracks that weren't there two years ago. New impact
craters formed since the 1970s suggest changes to
age-estimating models. And for three Mars summers in a row,
deposits of frozen carbon dioxide near Mars' south pole
have shrunk from the previous year's size, suggesting a
climate change in progress.

"Our prime mission ended in early 2001, but many of the
most important findings have come since then, and even
bigger ones might lie ahead," said Tom Thorpe, project
manager for Mars Global Surveyor at NASA's Jet Propulsion
Laboratory, Pasadena, Calif. The orbiter is healthy and
may be able to continue studying Mars for five to 10 more
years, he said.

Mars years are nearly twice as long as Earth years. The
orbiter's longevity has enabled monitoring of year-to-year
patterns on Mars, such as seasonal dust storms and changes
in the polar caps. "Mars is an active planet, and over a
range of timescales changes occur, even in the surface,"
said Dr. Michael Malin of Malin Space Science Systems,
San Diego, principal investigator for the Mars Orbiter
Camera on Mars Global Surveyor.

"To see new gullies and other changes in Mars surface
features on a time span of a few years presents us with a
more active, dynamic planet than many suspected before
Mars Global Surveyor got there," said Michael Meyer, Mars
Exploration Program chief scientist, NASA Headquarters,
Washington.

Two gullies appear in an April 2005 image of a sand-dune
slope where they did not exist in July 2002. The Mars
Orbiter Camera team has found many sites on Mars with
fresh-looking gullies, and checked back at more than 100
gullied sites for possible changes between imaging dates,
but this is the first such find. Some gullies, on slopes
of large sand dunes, might have formed when frozen carbon
dioxide, trapped by windblown sand during winter,
vaporized rapidly in spring, releasing gas that made the
sand flow as a gully-carving fluid.

At another site, more than a dozen boulders left tracks
when they rolled down a hill sometime between the taking
of images in November 2003 and December 2004. It is
possible that they were set in motion by strong wind or
by a "marsquake," Malin said.

Some changes are slower than expected. Studies suggest
new impact craters might appear at only about one-fifth
the pace assumed previously, Malin said. That pace is
important because crater counts are used to estimate the
ages of Mars surfaces.

The camera has recorded seasonal patterns of clouds and
dust within the atmosphere over the entire planet. In
addition, other instruments on Mars Global Surveyor
have provided information about atmospheric changes and
year-to-year patterns on Mars as the mission has
persisted. Daily mapping of dust abundance in Mars'
atmosphere by the Thermal Emission Spectrometer has
shown dust over large areas during three Mars southern
hemisphere summers in a row. However, the extent and
duration of dust storms varied from year to year.

Mars Global Surveyor was launched Nov. 7, 1996; entered
orbit around Mars Sept. 12, 1997; and returned the first
Mars data from its science instruments Sept. 15, 1997.
Beyond its own investigations, the orbiter provides
support for other Mars missions, such as landing-site
evaluations, atmospheric monitoring, communication
relay and imaging of hardware on the surface. JPL, a
division of the California Institute of Technology in
Pasadena, manages the mission for NASA's Science
Mission Directorate, Washington. JPL's industrial
partner is Lockheed Martin Space Systems, Denver,
which built and operates the spacecraft.

For newly released images on the Internet, visit:

http://www.nasa.gov/vision/universe/solarsystem/mgs-092005-images.html

and http://www.msss.com/mars_images/moc/2005/09/20/ .

For more information about NASA and agency programs on
the Internet, visit:

http://www.nasa.gov/home

-end-
Received on Tue 20 Sep 2005 05:15:51 PM PDT