[meteorite-list] NASA Curiosity Rover Finds Old Streambed On Martian Surface

[Ron Baalke]

Sept. 27, 2012

Dwayne Brown /Steve Cole 
Headquarters, Washington 
202-358-1726 / 202-358-0918 
dwayne.c.brown at nasa.gov / stephen.e.cole at nasa.gov 

Guy Webster / D.C. Agle 
Jet Propulsion Laboratory, Pasadena, Calif. 
818-354-5011 
guy.webster at jpl.nasa.gov / agle at jpl.nasa.gov 

RELEASE: 12-338

NASA ROVER FINDS OLD STREAMBED ON MARTIAN SURFACE

PASADENA, Calif. -- NASA's Curiosity rover mission has found evidence 
a stream once ran vigorously across the area on Mars where the rover 
is driving. There is earlier evidence for the presence of water on 
Mars, but this evidence - images of rocks containing ancient 
streambed gravels - is the first of its kind. 

Scientists are studying the images of stones cemented into a layer of 
conglomerate rock. The sizes and shapes of stones offer clues to the 
speed and distance of a long-ago stream's flow. 

"From the size of gravels it carried, we can interpret the water was 
moving about 3 feet per second, with a depth somewhere between ankle 
and hip deep," said Curiosity science co-investigator William 
Dietrich of the University of California, Berkeley. "Plenty of papers 
have been written about channels on Mars with many different 
hypotheses about the flows in them. This is the first time we're 
actually seeing water-transported gravel on Mars. This is a 
transition from speculation about the size of streambed material to 
direct observation of it." 

The finding site lies between the north rim of Gale Crater and the 
base of Mount Sharp, a mountain inside the crater. Earlier imaging of 
the region from Mars orbit allows for additional interpretation of 
the gravel-bearing conglomerate. The imagery shows an alluvial fan of 
material washed down from the rim, streaked by many apparent 
channels, sitting uphill of the new finds. 

The rounded shape of some stones in the conglomerate indicates 
long-distance transport from above the rim, where a channel named 
Peace Vallis feeds into the alluvial fan. The abundance of channels 
in the fan between the rim and conglomerate suggests flows continued 
or repeated over a long time, not just once or for a few years. 

The discovery comes from examining two outcrops, called "Hottah" and 
"Link" with the telephoto capability of Curiosity's mast camera 
during the first 40 days after landing. Those observations followed 
up on earlier hints from another outcrop, which was exposed by 
thruster exhaust as Curiosity, the Mars Science Laboratory Project's 
rover, touched down. 

"Hottah looks like someone jack-hammered up a slab of city sidewalk, 
but it's really a tilted block of an ancient streambed," said Mars 
Science Laboratory Project Scientist John Grotzinger of the 
California Institute of Technology in Pasadena. 

The gravels in conglomerates at both outcrops range in size from a 
grain of sand to a golf ball. Some are angular, but many are rounded. 

"The shapes tell you they were transported and the sizes tell you they 
couldn't be transported by wind. They were transported by water 
flow," said Curiosity science co-investigator Rebecca Williams of the 
Planetary Science Institute in Tucson, Ariz. 

The science team may use Curiosity to learn the elemental composition 
of the material, which holds the conglomerate together, revealing 
more characteristics of the wet environment that formed these 
deposits. The stones in the conglomerate provide a sampling from 
above the crater rim, so the team may also examine several of them to 
learn about broader regional geology. 

The slope of Mount Sharp in Gale Crater remains the rover's main 
destination. Clay and sulfate minerals detected there from orbit can 
be good preservers of carbon-based organic chemicals that are 
potential ingredients for life. 

"A long-flowing stream can be a habitable environment," said 
Grotzinger. "It is not our top choice as an environment for 
preservation of organics, though. We're still going to Mount Sharp, 
but this is insurance that we have already found our first 
potentially habitable environment." 

During the two-year prime mission of the Mars Science Laboratory, 
researchers will use Curiosity's 10 instruments to investigate 
whether areas in Gale Crater have ever offered environmental 
conditions favorable for microbial life. 

For more about Curiosity, visit: 

http://www.nasa.gov/msl 

You can follow the mission on Facebook and Twitter at: 

http://www.facebook.com/marscuriosity 

and 

http://www.twitter.com/marscuriosity 
	
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