Fwd = NASA: Mars was once 'soaking wet'
- NASA: Liquid water once on Mars
Evidence red planet was once 'soaking wet'
By Marsha Walton - CNN
(CNN) --Mission accomplished.
NASA scientists say the Mars rovers have found what they were looking for:
Hard evidence that the red planet was once "soaking wet."
"We have concluded the rocks here were once soaked in liquid water," said
Steve Squyres of Cornell University. He's the principal investigator for
the science instruments on Opportunity and its twin rover, Spirit.
"The second question we've tried to answer: Were these rocks altered by
liquid water? We believe definitively, yes," said Squyres.
Squyres and other NASA officials made the announcement at NASA
headquarters in Washington, after several days of giving tantalizing hints
that something significant had been discovered.
"Three and a half years ago, in July 2000, we were on stage here to talk
about sending two rovers to get evidence of past water. NASA and its
international partners have turned those dreams to reality," said Ed
Weiler, NASA associate administrator for space science.
Scientists used instruments on board the golf cart-sized rovers to study
the composition of the rocks and soil on the planet. The rocks' physical
appearance, plus the detection of sulfates, make the case for a watery
history, and more important, an environment that could have been
hospitable to life.
Spirit and Opportunity were sent to opposite sides of the planet with the
possibility of investigating different types of terrain. Spirit, the first
rover to arrive on January 3, landed near the Gusev Crater, which may once
have held a lake.
But geologists and other researchers at NASA's Jet Propulsion Laboratory
in Pasadena, California, were thrilled when they saw the possibilities
surrounding Opportunity, which landed three weeks later. It landed inside
a small crater in the Meridiani Planum, one of the flattest places on the
planet. And its landing site was within driving distance for the
spacecraft to reach an exposed slice of bedrock.
Since its landing January 25, Opportunity has used the same tools as a
human field geologist would to determine the chemical contents of the
rocks. Using an alpha particle X-ray spectrometer, a device that can
identify chemical elements, scientists have identified a high
concentration of sulfur in the bedrock.
Another instrument on board, a Moessbauer spectrometer, has detected an
iron sulfate mineral known as jarosite. From their knowledge of rocks on
earth, scientists say rocks with as much salt as this Mars rock either
formed in water, or had a long exposure to water after they were formed.
The scientists say these rocks could have formed in an acidic lake or even
a hot springs.
Scientists say the case for a watery past is further strengthened by the
pictures taken by the rovers' panoramic cameras and its microscopic
imager. One target rock, named "El Capitan," is filled with random
pockmarks. Geologists say a texture like that comes from sites where salt
crystals have formed in rocks that have sat in salt water.
Scientists say they have gained other clues from the physical appearance
of the rocks. They see a pattern called "crossbedding," which is often the
result of wind or water moving across the rock's surface.
The cost of the two rover missions is about $820 million dollars. With
solar panels and lithium-ion battery systems aboard, each rover is
expected to function and communicate with earth for about 90 Mars days,
known as "sols." That's equivalent to 92 earth days.
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