----- Original Message -----
Sent: Tuesday, March 23, 2004 2:15 PM
Subject: Standing Body of Water Left Its Mark in Mars
Rocks
MEDIA RELATIONS OFFICE
JET PROPULSION
LABORATORY
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PASADENA, CALIFORNIA 91109. TELEPHONE (818)
354-5011
http://jpl.convio.net/site/R?i=R2bmkarcc8pO-3BCLCXxIg..
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Guy
Webster (818) 354-5011
Jet Propulsion Laboratory, Pasadena,
Calif.
Donald Savage (202) 358-1547
NASA
Headquarters, Washington, D.C.
NEWS RELEASE:
2004-090
March 23, 2004
Standing Body of Water Left Its Mark in Mars
Rocks
NASA's Opportunity rover has demonstrated some rocks on Mars
probably
formed as deposits at the bottom of a body of gently
flowing
saltwater.
"We think Opportunity is parked on what was once
the shoreline of a
salty sea on Mars," said Dr. Steve Squyres of Cornell
University,
Ithaca, N.Y., principal investigator for the science payload
on
Opportunity and its twin Mars Exploration Rover, Spirit.
Clues
gathered so far do not tell how long or how long ago liquid
water covered
the area. To gather more evidence, the rover's
controllers plan to send
Opportunity out across a plain toward a
thicker exposure of rocks in the
wall of a crater.
NASA's Associate Administrator for Space Science Dr.
Ed Weiler said,
"This dramatic confirmation of standing water in Mars'
history builds
on a progression of discoveries about that most Earthlike of
alien
planets. This result gives us impetus to expand our ambitious
program
of exploring Mars to learn whether microbes have ever lived there
and,
ultimately, whether we can."
"Bedding patterns in some finely
layered rocks indicate the sand-sized
grains of sediment that eventually
bonded together were shaped into
ripples by water at least five centimeters
(two inches) deep, possibly
much deeper, and flowing at a speed of 10 to 50
centimeters (four to
20 inches) per second," said Dr. John Grotzinger,
rover science-team
member from the Massachusetts Institute of Technology,
Cambridge,
Mass.
In telltale patterns, called crossbedding and
festooning, some layers
within a rock lie at angles to the main layers.
Festooned layers have
smile-shaped curves produced by shifting of the loose
sediments'
rippled shapes under a current of water.
"Ripples that
formed in wind look different than ripples formed in
water," Grotzinger
said. "Some patterns seen in the outcrop that
Opportunity has been
examining might have resulted from wind, but
others are reliable evidence
of water flow."
According to Grotzinger, the environment at the time
the rocks were
forming could have been a salt flat, or playa, sometimes
covered by
shallow water and sometimes dry. Such environments on Earth,
either at
the edge of oceans or in desert basins, can have currents of
water
that produce the type of ripples seen in the Mars rocks.
A second line of evidence, findings of chlorine and bromine in
the
rocks, also suggests this type of environment. Rover
scientists
presented some of that news three weeks ago as evidence the
rocks had
at least soaked in mineral-rich water, possibly underground
water,
after they formed. Increased assurance of the bromine
findings
strengthens the case that rock-forming particles precipitated
from
surface water as salt concentrations climbed past saturation
while
water was evaporating.
Dr. James Garvin, lead scientist for
Mars and lunar exploration at
NASA Headquarters, Washington, said, "Many
features on the surface of
Mars that orbiting spacecraft have revealed to
us in the past three
decades look like signs of liquid water, but we have
never before had
this definitive class of evidence from the martian rocks
themselves.
We planned the Mars Exploration Rover Project to look for
evidence
like this, and it is succeeding better than we had any right to
hope.
Someday we must collect these rocks and bring them back to
terrestrial
laboratories to read their records for clues to the
biological
potential of Mars."
Squyres said, "The particular type of
rock Opportunity is finding,
with evaporite sediments from standing water,
offers excellent
capability for preserving evidence of any biochemical or
biological
material that may have been in the water."
Engineers at
NASA's Jet Propulsion Laboratory, Pasadena, Calif.,
expect Opportunity and
Spirit to operate several months longer than
their initial three-month
prime missions on Mars. To analyze hints of
crossbedding, mission
controllers programmed Opportunity to move its
robotic arm more than 200
times in one day, taking 152 microscope
pictures of layering in a rock
called "Last Chance."
JPL, a division of the California Institute of
Technology in Pasadena,
manages the Mars Exploration Rover Project for
NASA's Office of Space
Science, Washington. Images and additional
information about the
project are available on the Internet at
http://jpl.convio.net/site/R?i=6KuNBYCV2v9O-3BCLCXxIg..
,
http://jpl.convio.net/site/R?i=QYrJnLTYRS1O-3BCLCXxIg..
and
http://jpl.convio.net/site/R?i=sCvJMbnusy9O-3BCLCXxIg..
http://jpl.convio.net/site/R?i=Y-9inANRIuBO-3BCLCXxIg..
http://jpl.convio.net/site/R?i=bqihRWXud7tO-3BCLCXxIg..
http://jpl.convio.net/site/R?i=DHvPTKGq0L9O-3BCLCXxIg..
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