NASA Mission Finds New Clues To Guide Search For Life On Mars

Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster@jpl.nasa.gov

Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov

Robert Burnham 480-458-8207
Arizona State University, Tempe
robert.burnham@asu.edu

Tara Hicks-Johnson (808) 956-3151
University of Hawaii, Manoa
hickst@hawaii.edu

News Release: 2008-047 March 20, 2008

NASA Mission Finds New Clues to Guide Search for Life on Mars

PASADENA, Calif. - NASA's Mars Odyssey orbiter has found evidence of salt deposits.
These deposits point to places where water once was abundant and where evidence might
exist of possible Martian life from the Red Planet's past.

A team led by Mikki Osterloo of the University of Hawaii, Honolulu, found
approximately 200 places on southern Mars that show spectral characteristics consistent
with chloride minerals. Chloride is part of many types of salt, such as sodium chloride or
table salt. The sites range from about a square kilometer (0.6 square mile) to 25 times that
size.

"They could come from groundwater reaching the surface in low spots," Osterloo said.
"The water would evaporate and leave mineral deposits, which build up over years. The
sites are disconnected, so they are unlikely to be the remnants of a global ocean."

Scientists used Odyssey's Thermal Emission Imaging System, a camera designed and
operated by Arizona State University, Tempe, to take images in a range of visible light
and infrared wavelengths.
Thermal infrared wavelengths are useful for identifying different mineral and rock types
on the Martian surface. Osterloo found the sites by looking through thousands of images
processed to reveal, in false colors, compositional differences on the Martian surface.

Plotted on a Mars map, the chloride sites appear only in the southern highlands, the most
ancient rocks on Mars. Osterloo and seven co-authors report the findings in this week's
issue of the journal Science.

"Many of the deposits lie in basins with channels leading into them," said Philip
Christensen, co-author and principal investigator for the camera at Arizona State
University. "This is the kind of feature, like salt-pan deposits on Earth, that's consistent
with water flowing in over a long time."

Scientists think the salt deposits formed approximately 3.5 to 3.9 billion years ago.
Several lines of evidence suggest Mars then had intermittent periods with substantially
wetter and warmer conditions than today's dry, frigid climate.

Scientists looking for evidence of past life on Mars have focused mainly on a handful of
places that show evidence of clay or sulfate minerals. Clays indicate weathering by water,
and sulfates may have formed by water evaporation. The new research, however,
suggests an alternative mineral target to explore for biological remains.

"By their nature, salt deposits point to a lot of water, which potentially could remain
standing in pools as it evaporates," said Christensen. "That's crucial. For life, it's all about
a habitat that endures for some time."

Whether life ever has existed on Mars is the biggest scientific question driving Mars
research. On Earth, salt is good at preserving organic material. Bacteria have been
revived in the laboratory after being preserved in salt deposits for millions of years.

"This discovery demonstrates the continuing value of the Odyssey science mission, now
entering its seventh year. The more we look at Mars, the more fascinating a place it
becomes," said Jeffrey Plaut, Odyssey project scientist at NASA's Jet Propulsion
Laboratory, Pasadena, Calif.

"This is a wonderful and scientifically exciting result obtained from a relatively low cost
NASA Mars orbiter mission which still has years of life left," said Alan Stern, associate
administrator for NASA's Science Mission Directorate in Washington. "Hold on to your
hats, more exciting results from Mars are sure to be coming."

JPL, a division of the California Institute of Technology, Pasadena, manages Odyssey for
the NASA Science Mission Directorate. Lockheed Martin Space Systems, Denver, is the
prime contractor for the project and built the spacecraft. Additional information about
Odyssey is at http://www.nasa.gov/mission_pages/odyssey . More information about
the camera and the new findings is at http://themis.asu.edu .

-end-

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