[meteorite-list] Durable NASA Rover Beginning Ninth Year of Mars Work

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 24 Jan 2012 17:06:09 -0800 (PST)
Message-ID: <201201250106.q0P169g2019538_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.cfm?release=2012-022

Durable NASA Rover Beginning Ninth Year of Mars Work
Jet Propulsion Laboratory
January 24, 2012

Eight years after landing on Mars for what was planned as a three-month
mission, NASA's enduring Mars Exploration Rover Opportunity is working
on what essentially became a new mission five months ago.

Opportunity reached a multi-year driving destination, Endeavour Crater,
in August 2011. At Endeavour's rim, it has gained access to geological
deposits from an earlier period of Martian history than anything it
examined during its first seven years. It also has begun an
investigation of the planet's deep interior that takes advantage of
staying in one place for the Martian winter.

Opportunity landed in Eagle Crater on Mars on Jan. 25, 2004, Universal
Time and EST (Jan. 24, PST), three weeks after its rover twin, Spirit,
landed halfway around the planet. In backyard-size Eagle Crater,
Opportunity found evidence of an ancient wet environment. The mission
met all its goals within the originally planned span of three months.
During most of the next four years, it explored successively larger and
deeper craters, adding evidence about wet and dry periods from the same
era as the Eagle Crater deposits.

In mid-2008, researchers drove Opportunity out of Victoria Crater, half
a mile (800 meters) in diameter, and set course for Endeavour Crater, 14
miles (22 kilometers) in diameter.

"Endeavour is a window further into Mars' past," said Mars Exploration
Rover Program Manager John Callas, of NASA's Jet Propulsion Laboratory,
Pasadena, Calif.

The trek took three years. In a push to finish it, Opportunity drove
farther during its eighth year on Mars -- 4.8 miles (7.7 kilometers) --
than in any prior year, bringing its total driving distance to 21.4
miles (34.4 kilometers).

The "Cape York" segment of Endeavour's rim, where Opportunity has been
working since August 2011, has already validated the choice of Endeavour
as a long-term goal. "It's like starting a new mission, and we hit pay
dirt right out of the gate," Callas said.

The first outcrop that Opportunity examined on Cape York differs from
any the rover had seen previously. Its high zinc content suggests
effects of water. Weeks later, at the edge of Cape York, a bright
mineral vein identified as hydrated calcium sulfate provided what the
mission's principal investigator, Steve Squyres of Cornell University,
Ithaca, N.Y., calls "the clearest evidence for liquid water on Mars that
we have found in our eight years on the planet."

Mars years last nearly twice as long as Earth years. Entering its ninth
Earth year on Mars, Opportunity is also heading into its fifth Martian
winter. Its solar panels have accumulated so much dust since Martian
winds last cleaned them -- more than in previous winters -- the rover
needs to stay on a sun-facing slope to have enough energy to keep active
through the winter.

The rover team has not had to use this strategy with Opportunity in past
winters, though it did so with Spirit, farther from the equator, for the
three Martian winters that Spirit survived. By the beginning of the
rovers' fourth Martian winter, drive motors in two of Spirit's six
wheels had ceased working, long past their design lifespan. The impaired
mobility kept the rover from maneuvering to an energy-favorable slope.
Spirit stopped communicating in March 2010.

All six of Opportunity's wheels are still useful for driving, but the
rover will stay on an outcrop called "Greeley Haven" until mid-2012 to
take advantage of the outcrop's favorable slope and targets of
scientific interest during the Martian winter. After the winter, or
earlier if wind cleans dust off the solar panels, researchers plan to
drive Opportunity in search of clay minerals that a Mars orbiter's
observations indicate lie on Endeavour's rim.

"The top priority at Greeley Haven is the radio-science campaign to
provide information about Mars' interior," said JPL's Diana Blaney,
deputy project scientist for the mission. This study uses weeks of
tracking radio signals from the stationary rover to measure wobble in
the planet's rotation. The amount of wobble is an indicator of whether
the core of the planet is molten, similar to the way spinning an egg can
be used to determine whether it is raw or hard-boiled.

Other research at Greeley Haven includes long-term data gathering to
investigate mineral ingredients of the outcrop with spectrometers on
Opportunity's arm, and repeated observations to monitor wind-caused
changes at various scales.

The Moessbauer spectrometer, which identifies iron-containing minerals,
uses radiation from cobalt-57 in the instrument to elicit a response
from molecules in the rock. The half-life of cobalt-57 is only about
nine months, so this source has diminished greatly. A measurement that
could have been made in less than an hour during the rover's first year
now requires weeks of holding the spectrometer on the target.

Observations for the campaign to monitor wind-caused changes range in
scale from dunes in the distance to individual grains seen with the
rover's microscopic imager. "Wind is the most active process on Mars
today," Blaney said. "It is harder to watch for changes when the rover
is driving every day. We are taking advantage of staying at one place
for a while."

NASA's Jet Propulsion Laboratory, a division of the California Institute
of Technology in Pasadena, manages the Mars Exploration Rover Project
for the NASA Science Mission Directorate, Washington. More information
about Opportunity is online at: http://www.nasa.gov/rovers and
http://marsrovers.jpl.nasa.gov . You can follow the project on Twitter
at http://twitter.com/MarsRovers and on Facebook at
http://www.facebook.com/marsrovers .

Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster at jpl.nasa.gov

2012-022
Received on Tue 24 Jan 2012 08:06:09 PM PST