[meteorite-list] Mars Odyssey Finds New Clues to Guide the Search for Life on Mars

[Ron Baalke]

March 20, 2008

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

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

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

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

RELEASE: 08-084

NASA MISSION FINDS NEW CLUES TO GUIDE THE SEARCH FOR LIFE ON MARS

WASHINGTON - 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 half of a 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."

For additional information about Odyssey, visit: 

http://www.nasa.gov/mission_pages/odyssey

	
-end-