[meteorite-list] NASA's Twin Mars Rovers Continue Exploration

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Feb 15 11:28:56 2005
Message-ID: <200502151628.IAA13890_at_zagami.jpl.nasa.gov>

Dolores Beasley/Gretchen Cook-Anderson
Headquarters, Washington February 15, 2005
(Phone: 202/358-1753/0836)

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/354-6278)

John Bluck
Ames Research Center, Moffett Field, Calif.
(Phone: 650/604-5026/9000)

RELEASE: 05-044

NASA'S TWIN MARS ROVERS CONTINUE EXPLORATION

NASA's Spirit rover found a new class of water-affected rock, while
its twin, Opportunity, finished inspecting its own heat shield and
set a new martian driving record. The rovers successfully completed
their three-month primary missions in April 2004 and are working on
extended exploration missions.

"This is probably the most interesting and important rock Spirit has
examined," said Dr. Steve Squyres of Cornell University, Ithaca, N.Y.,
principal investigator for the rovers. The rock, dubbed "Peace," is an
exposure of bedrock in the Columbia Hills. The rock is in the Gusev
Crater, where Spirit landed 13 months ago. "This may be what the bones
of this mountain are really made of; it gives us even more compelling
evidence for water playing a major role for altering the rocks here,"
Squyres added.

Peace contains more sulfate salt than any other rock Spirit has examined.
Dr. Ralf Gellert, of Max-Planck-Institut fur Chemie, Mainz, Germany, said,
"Usually when we have seen high levels of sulfur in rocks at Gusev, it
has been at the very surface. The unusual thing about this rock is that
deep inside; the sulfur is still very high. The sulfur enrichment at the
surface is correlated with the amount of magnesium, which points to
magnesium sulfate."

Observations by Spirit show the rock contains significant
amounts of the minerals olivine, pyroxene and magnetite, all of which
are common in some types of volcanic rock. The rock's texture appears
to be sand-size grains coated with a material loosely binding the rock
together. Spirit's rock abrasion tool dug about 1 centimeter (0.4 inch)
deep in two hours.

"It looks as if you took volcanic rocks that were ground into little
grains, and then formed a layered rock with them cemented
together by a substantial quantity of magnesium-sulfate salt," Squyres
said. "Where did the salt come from? We have two working hypotheses we
want to check by examining more rocks. It could come from liquid water
with magnesium sulfate salt dissolved in it, percolating through the
rock, then evaporating and leaving the salt behind. Or it could come
from weathering by dilute sulfuric acid reacting with magnesium-rich
minerals that were already in the rock. Either case involves water,"
he said.

Opportunity used its microscopic imager last week to examine a cross
section of the heat shield that protected the spacecraft as it
slammed into Mars' atmosphere. This is the first time experts have
been able to examine a heat shield after it entered another
planet's atmosphere. Engineers expect the findings to aid design
for future missions.

"We've identified each broken piece of the heat shield. We know
there's a lot of data there, but we still need to analyze it," said
Ethiraj Venkatapathy of NASA's Ames Research Center, Moffett Field,
Calif.

Christine Szalai, a spacecraft engineer at NASA's Jet Propulsion
Laboratory (JPL), Pasadena, Calif., said, "We are examining the
images to determine the depth of charring in the heat shield
material. In the initial look, we didn't see any surprises. We
will be working for the next few months to analyze the performance of
the heat shield," Szalai said.

Since leaving the heat shield, Opportunity has been traveling south
to explore new sites. The rover set a single-day martian driving
record, covering 154.65 meters (507.4 feet) on Jan. 28.
Two days later, it drove even farther, 156.55 meters (513.6 feet). The
first 90 meters (295 feet) of each drive was performed in blind-drive
mode, following a route planners created from stereo images from the
rover and maps created from orbital imagery. The rest was autonomous
driving, with the rover choosing its own route to avoid any hazards
it perceived in stereo images taken along the way.

"The terrain we're crossing is so flat we can see a long way ahead,"
said JPL rover planner Frank Hartman, who teamed with Jeff
Biesiadecki to plot the drive. "Opportunity has paused for some
trenching, but in a few days we'll put the pedal to the metal
again."

For Images and additional information about the rovers on the
Internet, visit:

http://www.nasa.gov/vision/universe/solarsystem/mer_main.html

For information about NASA and agency programs on the Internet,
visit:

http://www.nasa.gov

-end-
Received on Tue 15 Feb 2005 11:28:41 AM PST