[Fwd: Spirit Adds Clues About History of Rocks in Martian Hills]
> From: "NASA Jet Propulsion Laboratory"
> Date: 2004/11/04 Thu PM 02:53:44 ESTMartian Hills
> To: "Vern Gambino" <vgambino1@...>
> Subject: Spirit Adds Clues About History of Rocks in
> MEDIA RELATIONS OFFICE
> JET PROPULSION LABORATORY
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> Guy Webster (818) 354-6278
> Jet Propulsion Laboratory, Pasadena, Calif.
> Donald Savage (202) 358-1547
> NASA Headquarters, Washington, D.C.
> News Release: 2004-269 November 4, 2004
> Spirit Adds Clues About History of Rocks in Martian
> All the scientific tools on NASA's two Mars Exploration
> Rovers are still working well, a full 10 months after
> Spirit's dramatic landing.
> The ones on Spirit are adding fresh evidence about
> history of layered bedrock in a hill the rover isclimbing.
> "Our leading hypothesis is that these rocks originated
> volcanic ash that fell from the air or moved in ground-altered by
> hugging ash flows, and that minerals in them were
> water," said Dr. Ray Arvidson of WashingtonUniversity, St.
> Louis, deputy principal investigator for the mission.conclusion,
> "This is still a working hypothesis, not a firm
> but all the instruments have contributed clues that fit,"he
> said. "However, it is important to point out that wehave
> just begun to characterize the textures, mineralogyand
> chemistry of these layered rocks. Other hypothesesfor their
> origin focus on the role of transport and deposition byWe are
> water. In fact, it may turn out that volcanism, water and
> wind have produced the rocks that Spirit is examining.
> just beginning to put together the big picture."in April.
> Both rovers completed three-month primary missions
> NASA has extended their missions twice becausethey have
> remained productive longer than anticipated.has two
> "We're still making good progress even though Spirit
> types of problems with its wheels," said Jim Erickson,rover
> project manager at NASA's Jet Propulsion Laboratory,problems
> Pasadena, Calif. "We are working around those
> successfully, but they might be a sign of things tocome, as
> mechanical parts wear out during our exploration ofMars."
> One question for continuing investigations as Spirit
> for rocks higher in the "Columbia Hills," is what theminerals.
> environment was like when water altered the
> Possibilities include water in the volcanic magmamixture
> before the ash erupted, surface water transporting theash
> while it was still loose after the eruption, and groundwater
> soaking through the rocks that solidified from thelayered rock
> accumulated ash.
> Some clues for a volcanic-ash origin come from a
> dubbed "Uchben." Researchers pointed Spirit'smicroscopic
> imager at a spot on Uchben scoured with the rockabrasion
> tool. The images reveal sand-size particles, many ofthem
> sharply angular in shape and some quite rounded.The
> angularity is consistent with transport by an eruption.usually
> Particles carried across the surface by wind or water
> tumble together and become more rounded.Uchben's rounded
> particles may be volcanic clumps, may beconcretions similar
> to what Opportunity has found, or may be particlestumbled in
> a water environment.by the
> Evidence for alteration by water comes mainly from
> identification of minerals and elements in the rocks
> rover's Moessbauer spectrometer and alpha particleX-ray
> The rovers' principal investigator, Dr. Steve Squyres of
> Cornell University, Ithaca, N.Y., said, "We have really
> headway just in the last several weeks inunderstanding these
> rocks. The most likely origin is debris that blasted outof a
> volcano, was transported by air or water to its presentcalled
> location, and settled out in layers."
> Opportunity, meanwhile, examined a lumpy boulder
> "Wopmay" inside "Endurance Crater." The slope ofthe ground
> and loose surface material around the rock preventedrock
> Opportunity from getting firm enough footing to use its
> abrasion tool. Evidence from the spectrometers andearlier
> microscopic imager is consistent with scientists'
> hypothesis that rocks near the bottom of the craterwere
> affected by water both before and after the craterformed.
> The evidence is still not conclusive, Squyres said.Cliff," a
> Opportunity is heading toward the base of "Burns
> tall exposure of layered rock in the wall of the crater.traction
> However, if the rover encounters more of the poor
> found around Wopmay, planners may change courseand drive up
> out of the crater.in
> JPL, a division of the California Institute of Technology
> Pasadena, manages the Mars Exploration Roverproject for
> NASA's Science Mission Directorate, Washington.Images and
> additional information about the project are availablefrom
> JPL at http://marsrovers.jpl.nasa.gov and fromCornell
> University at http://athena.cornell.edu .Propulsion Labratory, please go to
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