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Source : http://www.thejakartapost.com/news/2012/09/28/mars-rover-curiosity-finds-signs-ancient-
stream.html
Mars Rover Curiosity Finds Signs of Ancient Stream
Writtened by :
Alicia Chang, The Associated Press, Los Angeles | Sci-Tech
Fri, September 28 2012, 10:56 AM
The NASA rover Curiosity has beamed back pictures of bedrock that suggest a fast-moving stream, possibly waist-deep, once flowed on Mars a find that the mission's chief
scientist called exciting. There have been previous signs that water existed on the red planet
long ago, but the images released Thursday showing pebbles rounded off, likely by water,
offered the most convincing evidence so far of an ancient streambed.
There was "a vigorous flow on the surface of Mars," said chief scientist John
Grotzinger of the California Institute of Technology. "We're really excited about this."
The discovery did not come as a complete surprise. NASA decided to plunk Curiosity
down inside Gale Crater near the Martian equator because photos from space hinted that
the spot possessed a watery past. The six-wheeled rover safely landed Aug. 5 after a nail-biting plunge through the Martian atmosphere. It's on a two-year, $2.5 billion mission to
study whether the Martian environment could have been favorable for microbial life.
Present day Mars is a frozen desert with no hint of water on its radiation-scarred
surface, but geological studies of rocks by previous missions suggest the planet was warmer
and wetter once upon a time.
The latest evidence came from photos that Curiosity took revealing rounded pebbles
and gravel a sign that the rocks were transported long distances by water and smoothed
out.
The size of the rocks
ranging from a sand grain to a golf ball
indicates that they
could not have been carried by wind, said mission scientist Rebecca Williams of the
Planetary Science Institute in Tucson, Arizona.
Though Curiosity did not use its high-tech instruments to drill into the rocks or
analyze their chemical makeup, Grotzinger said scientists were sure that water played a role
based on just studying the pictures.
It's unclear how long the water persisted on the surface, but it easily could have
lasted "thousands to millions of years," said mission scientist Bill Dietrich of the University of
California, Berkeley.
Curiosity chanced upon the dried-up streambed while driving to Glenelg, an
intriguing spot where three types of terrain meet. Its ultimate destination is Mount Sharp, a
mountain rising from the center of crater floor, but it was not expected to travel there until
the end of the year.
Finding past water is a first step toward learning whether the environment could
have supported microbes. Scientists generally agree that besides water and an energy
source such as the sun, organic carbon is a necessary prerequisite for life.
While an ancient streambed holds promise as a potentially habitable environment,
scientists don't think it's a good place to preserve the carbon building blocks of life. That's
why the rover will continue its trek to the foothills of Mount Sharp where there's a better
chance of finding organics.