From: LARRY KLAES (ljk4_at_msn.com)
Date: Thu Feb 19 2004 - 21:09:23 PST
>From: NASA Jet Propulsion Laboratory <info_at_jpl.nasa.gov>
>Reply-To: NASA Jet Propulsion Laboratory <info_at_jpl.nasa.gov>
>To: ljk4_at_msn.com
>Subject: Opportunity Examines Trench as Spirit Prepares to Dig One
>Date: Thu, 19 Feb 2004 17:21:44 -0600
>
>Guy Webster (818) 354-5011
>Jet Propulsion Laboratory, Pasadena, Calif.
>
>Donald Savage (202) 358-1547
>NASA Headquarters, Washington, D.C.
>
>News Release: 2004-066 February 19, 2004
>
>Opportunity Examines Trench as Spirit Prepares to Dig One
>
>By inspecting the sides and floor of a hole it dug on Mars,
>NASA's Opportunity rover is finding some things it did not
>see beforehand, including round pebbles that are shiny and
>soil so fine-grained that the rover's microscope can't make
>out individual particles.
>
>"What's underneath is different than what's at the immediate
>surface," said Dr. Albert Yen, rover science team member at
>NASA's Jet Propulsion Laboratory, Pasadena, Calif.
>
>Meanwhile, NASA's other Mars Exploration Rover, Spirit, has
>reached a site with such interesting soil that scientists
>have decided to robotically dig a hole there, too. Spirit's
>trenching at a shallow depression dubbed "Laguna Hollow"
>could answer questions about whether traits on the soil
>surface resulted from repeated swelling and shrinking of an
>upper layer bearing concentrated brine, among other
>possibilities.
>
>Opportunity has manipulated its robotic arm to use its
>microscope on five different locations within the trench the
>rover dug on Monday. It has also taken spectrometer readings
>of two sites. "We've given the arm a very strenuous workout,"
>said JPL's Dr. Eric Baumgartner, lead engineer for the arm.
>The accuracy of the tool placements -- within 5 millimeters,
>or less than a quarter inch -- is remarkable for mobile
>robotics on Earth, much less on Mars.
>
>Once data are analyzed from the alpha particle X-ray
>spectrometer and the Moessbauer spectrometer about what
>elements and what iron-bearing minerals are present, the
>differences between the subsurface and the surface will be
>easier to interpret, Yen said.
>
>While Opportunity has been digging and examining its trench
>this week, it has also been catching up on transmission of
>pictures and information from its survey last week of a rock
>outcrop along the inner wall of the small crater in which the
>rover is working.
>
>Both rovers can communicate directly with Earth, but JPL's
>Andrea Barbieri, telecommunication system engineer, reported
>that 66 percent of the 10 gigabits of data they have returned
>so far has come via relays by NASA's Mars Odyssey orbiter and
>another 16 percent via relays by NASA's Mars Global Surveyor.
>
>Based on the outcrop survey, scientists have chosen a feature
>they have dubbed "El Capitan" as the next target for
>intensive investigation by Opportunity.
>
>"We've planned our assault on the outcrop," said Dr. Steve
>Squyres of Cornell University, Ithaca, N.Y., principal
>investigator for the rovers' science instruments. "The whole
>stack of rocks seems to be well exposed here," he said of the
>chosen target. Upper and lower portions appear to differ in
>layering and weathering characteristics. Planners anticipate
>that Opportunity's arm will be able to reach both the upper
>and lower parts from a single parking spot in front of "El
>Capitan."
>
>Halfway around the planet, Spirit will be told to use a front
>wheel to dig a trench during the martian day, or "sol," that
>will end at 12:36 p.m. Friday, PST.
>
>Some soil in "Laguna Hollow" appeared to stick to Spirit's
>wheels. Possible explanations include very fine-grained dust
>or concentrated salt making the soil sticky, said Dr. Dave
>Des Marais, a rover science team member from NASA Ames
>Research Center, Moffett Field, Calif. Pictures of the
>surface there also show pebbles arranged in clusters or lines
>around lighter patches Des Marais described as "miniature
>hollows." This resembles patterned ground on Earth that can
>result from alternating expansion and shrinkage of the soil.
>Possible explanations for repeated expanding and contracting
>include cycles of freezing and thawing or temperature swings
>in salty soil.
>
>After trenching to seek clues about those possibilities,
>Spirit will continue on its trek toward the rim of a crater
>nicknamed "Bonneville," now estimated to be about 135 meters
>(443 feet) away from the rover. Spirit has already driven
>128 meters (420 feet).
>
>The rovers' main task is to explore their landing sites for
>evidence in the rocks and soil about whether the sites' past
>environments were ever watery and possibly suitable for
>sustaining life.
>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://jpl.convio.net/site/R?i=5XWKhXyaazhO-3BCLCXxIg.. and from Cornell
> http://jpl.convio.net/site/R?i=PQzX1XSmE8hO-3BCLCXxIg..
>
>University at http://jpl.convio.net/site/R?i=FBJSFbDP-FZO-3BCLCXxIg.. .
> http://jpl.convio.net/site/R?i=XfNXTT6BN6ZO-3BCLCXxIg..
>
> -end-
>
>
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