[meteorite-list] Martian Crater Once May Have Held Groundwater-Fed Lake

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Sun, 20 Jan 2013 12:56:38 -0800 (PST)
Message-ID: <201301202056.r0KKucaE002736_at_zagami.jpl.nasa.gov>

Jan. 20, 2013

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

Alan Fischer
Planetary Science Institute, Tucson, Ariz.
520-382-0411
fischer at psi.edu

RELEASE: 13-026

MARTIAN CRATER ONCE MAY HAVE HELD GROUNDWATER-FED LAKE

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 (MRO), 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 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, MRO and its six instruments have provided more
high-resolution data about the Red Planet than all other Mars
orbiters combined. Data is 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 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 MRO project
scientist Rich Zurek of NASA's Jet Propulsion Laboratory (JPL) in
Pasadena, Calif.

The Johns Hopkins University Applied Physics Laboratory in Laurel,
Md., provided and operates CRISM. JPL manages MRO 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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Received on Sun 20 Jan 2013 03:56:38 PM PST