Martian Crater May Once Have Held Groundwater-Fed Lake

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Guy Webster 818-354-6278
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Alan Fischer 520-382-0411
Planetary Science Institute, Tucson, Ariz.
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Dwayne Brown 202-358-1726
NASA Headquarters, Washington
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News release: 2013-028 Jan. 20, 2013

Martian Crater May Once Have Held Groundwater-Fed Lake

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.php?release=2013-028&cid=release_2013-028

PASADENA, Calif. -- A NASA spacecraft is providing new evidence of a wet underground
environment on Mars that adds to an increasingly complex picture of the Red Planet's early
evolution.

The new information comes from researchers analyzing spectrometer data from NASA's Mars
Reconnaissance Orbiter, which looked down on the floor of McLaughlin Crater. The Martian
crater is 57 miles (92 kilometers) in diameter and 1.4 miles (2.2 kilometers) deep. McLaughlin's
depth apparently once allowed underground water, which otherwise would have stayed hidden,
to flow into the crater's interior.

Layered, flat rocks at the bottom of the crater contain carbonate and clay minerals that form in
the presence of water. McLaughlin lacks large inflow channels, and small channels originating
within the crater wall end near a level that could have marked the surface of a lake.

Together, these new observations suggest the formation of the carbonates and clay in a
groundwater-fed lake within the closed basin of the crater. Some researchers propose the crater
interior catching the water and the underground zone contributing the water could have been wet
environments and potential habitats. The findings are published in Sunday's online edition of
Nature Geoscience.

"Taken together, the observations in McLaughlin Crater provide the best evidence for carbonate
forming within a lake environment instead of being washed into a crater from outside," said
Joseph Michalski, lead author of the paper, which has five co-authors. Michalski also is affiliated
with the Planetary Science Institute in Tucson, Ariz., and London's Natural History Museum.

Michalski and his co-authors used the Compact Reconnaissance Imaging Spectrometer for Mars
(CRISM) on the Mars Reconnaissance Orbiter (MRO) to check for minerals such as carbonates,
which are best preserved under non-acidic conditions.

"The MRO team has made a concerted effort to get highly processed data products out to
members of the science community like Dr. Michalski for analysis," said CRISM Principal
Investigator Scott Murchie of the Johns Hopkins University Applied Physics Laboratory in
Laurel, Md. "New results like this show why that effort is so important."

Launched in 2005, the Mars Reconnaissance Orbiter and its six instruments have provided more
high-resolution data about the Red Planet than all other Mars orbiters combined. Data are made
available for scientists worldwide to research, analyze and report their findings.

"A number of studies using CRISM data have shown rocks exhumed from the subsurface by
meteor impact were altered early in Martian history, most likely by hydrothermal fluids,"
Michalski said. "These fluids trapped in the subsurface could have periodically breached the
surface in deep basins such as McLaughlin Crater, possibly carrying clues to subsurface
habitability."

McLaughlin Crater sits at the low end of a regional slope several hundreds of miles, or
kilometers, long on the western side of the Arabia Terra region of Mars. As on Earth,
groundwater-fed lakes are expected to occur at low regional elevations. Therefore, this site
would be a good candidate for such a process.

"This new report and others are continuing to reveal a more complex Mars than previously
appreciated, with at least some areas more likely to reveal signs of ancient life than others," said
Mars Reconnaissance Orbiter Project Scientist Rich Zurek of NASA's Jet Propulsion Laboratory,
Pasadena, Calif.

The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., provided and
operates CRISM. JPL, a division of the California Institute of Technology in Pasadena, manages
the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate in Washington.
Lockheed Martin Space Systems in Denver built the orbiter.

To see an image of the carbonate-bearing layers in McLaughlin Crater, visit:
http://photojournal.jpl.nasa.gov/catalog/PIA16710 .

For more about the Mars Reconnaissance Orbiter mission, visit: http://www.nasa.gov/mro .

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