SETI bioastro: Fw: NASA's Mars Rovers Roll Into Martian Winter

From: LARRY KLAES (ljk4_at_msn.com)
Date: Wed Jul 21 2004 - 07:42:39 PDT

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    ----- Original Message -----
    From: NASA Jet Propulsion Laboratory<mailto:info_at_jpl.nasa.gov>
    To: ljk4_at_msn.com<mailto:ljk4_at_msn.com>
    Sent: Friday, July 16, 2004 2:58 PM
    Subject: NASA's Mars Rovers Roll Into Martian Winter

    MEDIA RELATIONS OFFICE
    JET PROPULSION LABORATORY
    CALIFORNIA INSTITUTE OF TECHNOLOGY
    NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
    PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
    http://www.jpl.nasa.gov>

    Whitney Clavin (818) 354-4673
    Jet Propulsion Laboratory, Pasadena, Calif.

    Donald Savage (202) 358-1727
    NASA Headquarters, Washington

    RELEASE: 2004-184 July 16, 2004

    NASA's Mars Rovers Roll Into Martian Winter

    As winter approaches on Mars, NASA's Opportunity rover continues to
    inch deeper into the stadium-sized crater dubbed "Endurance." On the
    other side of the planet, the Spirit rover found an intriguing patch
    of rock outcrop while preparing to climb up the "Columbia Hills"
    backward. This unusual approach to driving is part of a creative plan
    to accommodate Spirit's aging front wheel.

    Spirit, with an odometer reading of over 3.5 kilometers (2.2 miles),
    has already traveled six times its designed capacity. Its right front
    wheel has been experiencing increased internal resistance, and recent
    efforts to mitigate the problem by redistributing the wheel's
    lubricant through rest and heating have been only partially
    successful.

    To cope with the condition, rover planners have devised a roundabout
    strategy. They will drive the rover backward on five wheels, rotating
    the sixth wheel only sparingly to ensure its availability for
    demanding terrain. "Driving may take us a little bit longer because it
    is like dragging an anchor," said Joe Melko, a rover engineer at
    NASA's Jet Propulsion Laboratory, Pasadena, Calif. "However, this
    approach will allow us to continue doing science much longer than we
    ever thought possible."

    On Thursday, July 15, Spirit successfully drove 8 meters (26 feet)
    north along the base of the Columbia Hills backward, dragging its
    faulty wheel. The wheel was activated about 10 percent of the time to
    surmount obstacles and to pull the rover out of trenches dug by the
    immobile wheel.

    Along the way, Spirit drove over what scientists had been hoping to
    find in the hills -- a slab of rock outcrop that may represent some of
    the oldest rocks observed in the mission so far. Spirit will continue
    to drive north, where it likely will encounter more outcrop.
    Ultimately, the rover will drive east and hike up the hills backward
    using all six wheels.

    "A few months ago, we weren't sure if we'd make it to the hills, and
    now here we are preparing to drive up into them," said Dr. Matt
    Golombek, a rover science-team member from JPL. "It's very exciting."

    For the past month, the Spirit rover has been parked near several
    hematite-containing rocks, including "Pot of Gold," conducting science
    studies and undergoing a long-distance "tuneup" for its right front
    wheel.

    Driving with the wheel disabled means that corrections might have to
    be made to the rover's steering if it veers off its planned path. This
    limits Spirit's accuracy, but rover planners working at JPL's rover
    test facility have come up with some creative commands that allow the
    rover to auto-correct itself to a limited degree.

    As Spirit prepares to climb upward, Opportunity is rolling downward.
    Probing increasingly deep layers of bedrock lining the walls of
    Endurance Crater at Meridiani Planum, the rover has observed a
    puzzling increase in the amount of chlorine. Data from Opportunity's
    alpha particle X-ray spectrometer show that chlorine is the only
    element that dramatically rises with deepening layers, leaving
    scientists to wonder how it got there. "We do not know yet which
    element is bound to the chlorine," said Dr. Jutta Zipfel, a rover
    science-team member from the Max Planck Institute for Chemistry,
    Mainz, Germany.

    Opportunity will roll down even farther into the crater in the next
    few days to see if this trend continues. It also will investigate a
    row of sharp, teeth-like features dubbed "Razorback," which may have
    formed when fluid flowed through cracks, depositing hard minerals.
    Scientists hope the new data will help put together the pieces of
    Meridiani's mysterious and watery past. "Razorback may tell us more
    about the history of water at Endurance Crater," said Dr. Jack Farmer,
    a rover science-team member from Arizona State University, Tempe.

    Rover planners are also preparing for the coming Martian winter, which
    peaks in mid-September. Dwindling daily sunshine means the rovers
    will have less solar power and take longer to recharge. Periods of
    rest and "deep sleep" will allow the rovers to keep working through
    the winter at lower activity levels. Orienting the rovers' solar
    panels toward the north will also elevate power supplies. "The rovers
    might work a little bit more every day, or a little bit more every
    other day. We will see how things go and remain flexible," said Jim
    Erickson, project manager for the Mars Exploration Rover mission at
    JPL.

    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.

    Images and additional information about the project are available on
    the Internet at
    http://marsrovers.jpl.nasa.gov> and
    http://athena.cornell.edu> .

    -end-


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