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."


This image provides higher-resolution views of
a site where another observation indicates the
presence of chloride salt deposits.
Image Credit: NASA/JPL-Caltech/University of
Arizona/Arizona State University/University of
Hawaii

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.


Bright blue marks a deposit of chloride (salt)
minerals in the southern highlands of Mars in
this false-color image, which highlights mineral
composition differences.
Image Credit: NASA/JPL-Caltech/Arizona State
University/University of Hawaii

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 .


Media contact: 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

2008-047

Source: NASA - Missions - Mars Odyssey

Bright Exposures of Chloride Salt on Southern Mars

03.20.08

+ Larger image
+ High resolution - annotated(26.2 Mb)
+ High resolution - no annotation (26.2 Mb)

This image provides higher-resolution views of a site where another observation PIA10247 indicates the presence of chloride salt deposits. The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter took this image on March 30, 2007. The colors resemble natural appearance, but are not true color. The chloride mineral deposit looks bright in tone, like salt pans on Earth. The deposit seems to be emerging as overlying material erodes away.

Evidence that this site and about 200 other sites in the southern highlands of Mars bear deposits of chloride salts comes from observations by the Thermal Emission Imaging System on NASA's Mars Odyssey orbiter. The salt deposits typically lie within topographic depressions, as exemplified in this image. They point to places where water was once abundant, then evaporated, leaving the minerals behind.

Inset boxes show two areas in greater detail, revealing cracks that formed as the salt deposit dried. Scale bars are 1 kilometer (six-tenths of a mile) and 100 meters (110 yards).

The site lies at about 221 degrees east longitude and 38.8 degrees south latitude, within the rugged Terra Sirenum region of Mars. This view, taken during southern-hemisphere spring on Mars, is part of a full HiRISE image at posted at _http://hirise.lpl.arizona.edu/.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace & Technologies Corp., Boulder, Colo.

Image Credit: NASA/JPL-Caltech/University of Arizona/Arizona State University/University of Hawaii

Source: NASA - Missions - MRO - Multimedia

Chloride Salt Deposit in Southern Highlands of Mars

03.20.08

+ Larger image
+ High resolution - annotated(5.7 Mb)
+ High resolution - no annotation (5.7 Mb)

Bright blue marks a deposit of chloride (salt) minerals in the southern highlands of Mars in this false-color image, which highlights mineral composition differences. The Thermal Emission Imaging System (THEMIS) camera on NASA's Mars Odyssey orbiter made this observation. Researchers using THEMIS reported in March 2008 that they have found about 200 such deposits of chloride salts. Observations by THEMIS and other instruments orbiting Mars indicate that these deposits typically lie within topographic depressions. The salt deposits suggest that Mars was much wetter long ago. They point to places where water was once abundant, then evaporated, leaving the minerals behind.

This site lies at about 221 degrees east longitude and 38.8 degrees south latitude, within the rugged Terra Sirenum region of Mars. The view is a portion of an image taken by THEMIS on Dec. 11, 2003. The full image is at http://themis-data.asu.edu/img/I08831002?tab=1 .

The scale bar is about 10 kilometers (6.2 miles). The black rectangle indicates the outline of a higher resolution view, available as PIA10248.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Odyssey mission for the NASA Science Mission Directorate, Washington. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. Lockheed Martin Space Systems, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter.

Image Credit: NASA/JPL-Caltech/Arizona State University/University of Hawaii

Source: NASA - Missions - MRO - Multimedia

The Arizona State University (ASU) press release is reproduced below:



Scientists using a Mars-orbiting camera designed and operated at ASU’s Mars Space Flight Facility have found the first evidence for deposits of chloride minerals – salts – in numerous places on Mars.

These deposits, say the scientists, show where water was once abundant and may also provide evidence for the existence of former Martian life.

A team of scientists led by Mikki Osterloo, of the University of Hawaii, used data from the Thermal Emission Imaging System (THEMIS) on NASA’s Mars Odyssey orbiter to discover and map the Martian chloride deposits. The Jet Propulsion Laboratory in Pasadena, Calif., manages the Mars Odyssey mission for NASA’s Science Mission Directorate.

THEMIS, which was developed at ASU, is a multiple-wavelength camera that takes images in five visual bands and 10 infrared ones. At infrared wavelengths, the smallest details THEMIS can see on the Martian surface are 330 feet (100 meters) wide.

The scientists found about 200 individual places in the Martian southern hemisphere that show spectral characteristics consistent with chloride minerals. These salt deposits occur in the middle to low latitudes all across the planet within ancient, heavily cratered terrain. The team’s report appears in the March 21 issue of the journal Science.

The team includes Philip Christensen, Joshua Bandfield and Alice Baldridge of ASU; Victoria Hamilton and Scott Anderson of the University of Hawaii; Timothy Glotch of Stony Brook University; and Livio Tornabene of the University of Arizona.

Lead author Osterloo found the sites by looking through thousands of THEMIS images processed to reveal, in false colors, compositional differences on the Martian surface.

“I started noting these sites because they showed up bright blue in one set of images, green in a second set, and yellow-orange in a third,” she says.

Adds Christensen: “THEMIS gives us a good look at the thermal infrared, the best part of the spectrum for identifying salt minerals by remote sensing from orbit.”

When plotted on a global map of Mars, the chloride sites appeared only in the southern highlands, the most ancient rocks on Mars.

Lay of the land

Christensen characterizes the sites’ geological setting this way: “Many of the deposits lie in basins with channels leading into them. This is the kind of feature, like salt-pan deposits on Earth, that’s consistent with water flowing in over a long time.”

Christensen, a Regents’ Professor of Geological Sciences at ASU’s School of Earth and Space Exploration in the College of Liberal Arts and Sciences, designed THEMIS and is the instrument’s principal investigator.

“The deposits range in area from about one square kilometer to about 25 square kilometers,” or about 0.4 square mile to about 10 square miles, Osterloo says.

“Because the deposits appear to be disconnected from each other, we don’t think they all came from one big, global body of surface water,” she says. “They could come from groundwater reaching the surface in low spots. The water would evaporate and leave mineral deposits, which build up over years.”

The scientists think the salt deposits formed mostly in the middle to late Noachian epoch, a time that researchers have dated to about 3.9 billion to 3.5 billion years ago. Several lines of evidence suggest Mars then had intermittent periods of substantially wetter and warmer conditions than today’s dry, frigid climate.

Looking for life

Until now, 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. The reasoning is that clays indicate weathering by water and that sulfates may form 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 could potentially remain standing in pools as it evaporates,” Christensen says.

That’s crucial, he says, adding: “For life, it’s all about a habitat that endures for some time.”

There also could be a “concentrating effect,” Christensen says.

“The deposits lie in what are probably sedimentary basins,” he says. “If you look upstream, you might find only a trace of organic materials because they’re thinly dispersed.”

But over a long period of time, he says, “the water flowing into a basin can concentrate the organic materials, and they could be well preserved in the salt.”

Whether or not the Red Planet ever had life is the biggest scientific question driving Mars research. On Earth, salt has proven remarkably good at preserving organic material. For example, bacteria have been revived in the laboratory after being preserved in salt deposits for millions of years.

NASA is studying potential landing sites for its Mars Science Laboratory (MSL), a new-generation rover due for launch in fall 2009. Sites featuring clay deposits number heavily in the short list of candidate places to send the rover.

“Scientists have studied Martian clay mineral sites for years now, and it’s natural they should be considered as targets for the Mars Science Laboratory rover,” Christensen says. “However, the discovery of chloride minerals in topographic basins within the oldest rocks on Mars should also be considered as an alternative mineralogy for MSL or future rovers to explore.”

Robert Burnham, robert.burnham@asu.edu
(480) 458-8207
Mars Space Flight Facility

Source: ASU News Release