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ZL2VAL > ROVERS 03.04.04 13:37l 116 Lines 5224 Bytes #999 (0) @ WW
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Sent: 040403/1122Z @:ZL2AB.#46.NZL.OC #:38475 [New Plymouth] FBB7.00g
From: ZL2VAL@ZL2AB.#46.NZL.OC
To : ROVERS@WW
NEWS RELEASE: 2004-93
April 01, 2004
Spirit Finds Multi-Layer Hints of Past Water at Mars' Gusev Site
Clues from a wind-scalloped volcanic rock on Mars investigated by NASA's
Spirit rover suggest repeated possible exposures to water inside Gusev
Crater, scientists said Thursday.
Gusev is halfway around the planet from the Meridiani region where
Spirit's twin, Opportunity, recently found evidence that water used to
flow across the surface.
"This is not water that sloshed around on the surface like what appears
to have happened at Meridiani. We're talking about small amounts of
water, perhaps underground," said Dr. Hap McSween, a rover science team
member from the University of Tennessee, Knoxville.
"The evidence is in the form of multiple coatings on the rock, as well
as fractures that are filled with alteration material and perhaps little
patches of alteration material," McSween said during a press conference
at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
The rock, called "Mazatzal" after mountains in Arizona, lies partially
buried near the rim of the crater informally named "Bonneville" inside
the much larger Gusev Crater. Its light- toned appearance grabbed
scientists' attention. After Spirit's rock abrasion tool brushed two
patches on the surface with wire bristles, a gray, darker layer could be
seen under the tan topcoat. The rock abrasion tool ground into the
surface with diamond cutting teeth on March 26. Then, after an
examination of the newly exposed material, it ground deeper into the
rock two days later. A lighter-gray interior lies under the darker
layer, and a bright stripe cuts across both.
Dr. Jeff Johnson, a science team member from the U.S. Geological
Survey's Astrogeology Team, Flagstaff, Ariz., said the stripe "seems to
be a fracture that water has flowed through, potentially with minerals
precipitating from that fluid and lining the walls of the crack."
He and other scientists stressed that the interpretations are
preliminary. "The team is, as always, trying to find time to digest
these observations while also preparing for the next day's operations,"
Johnson said.
Spirit's alpha particle X-ray spectrometer checked what chemical
elements were close to the surface of untreated, brushed, once-drilled
and twice-drilled patches. "Miracles, miracles, miracles. We have a lot
of work to do," the instrument's lead scientist, Dr. Rudi Rieder of the
Max Planck Institute, Mainz, Germany, exclaimed about the results. For
example, the ratio of bromine to chlorine seen inside the rock is
unusually high and possibly a clue to alteration by water.
The final experiment on Mazatzal was to scrub the surface with the rock
abrasion tool in a pattern of five circles arranged in a ring, with a
sixth circle in the center. Besides creating a rock-art daisy, this task
by the engineers of New York-based Honeybee Robotics, as well as JPL,
produced a brushed patch big enough to fill the field of view of
Spirit's miniature thermal emission spectrometer, said Dr. Steve Ruff of
Arizona State University, Tempe. The tan outer surface appears to have a
strikingly different mineral composition than the dark gray coating
exposed by the brushing, but more time is needed to complete the
analysis, he said.
McSween proposed that the light outer coat, dark inner coat and bright
veins could have resulted from three different periods of the rock being
buried, altered by fluids and unburied.
While scientists await transmission of additional data Spirit has
collected about Mazatzal, the rover will be making its way toward the
"Columbia Hills" about 2.3 kilometers (1.3 miles) away. Spirit left the
rock and drove 36.5 meters (120 feet) early Thursday.
Opportunity set a one-day driving record on Mars on March 27 by covering
48.9 meters (160 feet) toward a rock called "Bounce Rock" because airbag
bounce marks show that the spacecraft hit it on landing day two months
ago. "We're looking to break that record again very soon with longer and
longer drives," said JPL's Chris Lewicki, flight director.
Before moving on across the plains of Meridiani, though, Opportunity
will complete an investigation it has begun of Bounce Rock. The rock is
unlike any seen on Mars before, said Dr. Jim Bell, lead scientist for
the rovers' panoramic cameras. "There are some shiny surfaces on this
rock," he said, describing them as "almost mirrorlike."
The two rovers' 18 cameras have now taken more than 20,000 images. 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, D.C.
Images and additional information about the project are available from
JPL at http://marsrovers.jpl.nasa.gov
and from Cornell University, Ithaca, N.Y., at http://athena.cornell.edu
=========================
73 de Alan, (Sysop ZL2AB).
AX25:ZL2VAL@ZL2AB.#46.NZL.OC
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Message timed: 23:19 on 2004-Apr-03 (NZT)
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Points to ponder
~~~~~~~~~~~~~~~~
Marriage
~~~~~~~~
The most effective way to remember your wife's birthday is to forget it
once.
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