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

[Ron Baalke]

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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