- LOS ANGELES (AP) -- A year
and a half after twin robot rovers thrilled space fans with their hijinks
on Mars, NASA is heading there again.
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- A fourth Mars orbiter is set to blast off Wednesday,
carrying some of the most sophisticated science instruments ever sent into
space. Circling the Red Planet, the Mars Reconnaissance Orbiter will scan
the desolate surface in search of sites to land more robotic explorers
in the next decade.
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- "It's time we start peeling back the onion layer
and start looking at Mars from different vantage points," said project
manager James Graf of the Jet Propulsion Laboratory in Pasadena.
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- Like the three current spacecraft flying around Mars
-- including a European orbiter -- the latest probe will seek evidence
of water and other signs that the planet could once have hosted life. The
$720-million (U.S.) mission, which launches from Cape Canaveral, Fla.,
will also serve as a communications link to relay data to Earth.
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- Its powerful camera can snap the sharpest pictures yet
of the planet's rust-coloured surface, with six times higher resolution
than past images.
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- NASA took its first close-up pictures of Mars in 1965
when the Mariner 4 spacecraft zipped past the planet and snapped fewer
than two dozen photos.
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- Since then, numerous probes that have landed, orbited
or passed the planet have shot tens of thousands more images. But only
about 2 per cent of the planet has been viewed at high resolution.
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- "There are many unanswered questions about Mars,"
project scientist Richard Zurek said.
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- The two-tonne reconnaissance orbiter will be NASA's last
Mars orbiter this decade. Belt-tightening forced the space agency to cancel
a $500-million mission planned for 2009.
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- However, two more landing attempts are set during the
next four years. Scientists hope to use the orbiter's detailed mapping
to scout safe landing sites for the Phoenix Mars and Mars Science Laboratory
missions slated for 2007 and 2009, respectively.
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- The information gleaned by the spacecraft could also
help scientists decide where to send a lander during the next decade to
return the first samples of Martian rocks and soil to Earth.
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- The stationary Phoenix lander will use a long robotic
arm to explore the icy plains of the planet's north pole. Later, the mobile
Mars Science Laboratory will analyze rocks and soil in finer detail than
the rovers Spirit and Opportunity, which have uncovered geologic evidence
of past water activity.
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- The solar-powered rovers are still trekking across the
Martian surface, even though scientists had not expected the six-wheeled
machines to last more than three months in the hostile Martian environment.
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- The reconnaissance orbiter will also try to find two
ill-fated spacecraft -- NASA's Mars Polar Lander and Britain's Beagle 2
lander -- which lost contact during separate landing attempts. Earlier
this year, the company that operates a camera aboard one of the current
Mars orbiting spacecraft -- the Global Surveyor -- spotted what appeared
to be the wreckage of Polar Lander on grainy black-and-white images.
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- The Mars Reconnaissance Orbiter should reach Mars' orbit
in mid-March next year.
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- Along with its telescopic camera, the orbiter's payload
includes ground-penetrating radar that can probe up to a third of a mile
beneath surface rock and ice for evidence of water. Other instruments can
track daily weather changes and identify minerals.
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- Today, Mars is cold and dry with large caps of frozen
water at its poles. But scientists think the planet was a wetter and possibly
warmer place eons ago -- conditions that might be conducive to life.
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- After the imaging phase, the orbiter will switch to its
other role as a communication relay for Mars lander missions. It will be
equipped with a powerful antenna that can transmit 10 times more data per
minute than the current trio of satellites that includes NASA's Global
Surveyor and Mars Odyssey and the European Space Agency's Mars Express.
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- "We will have a fire hose of data coming back instead
of bringing it back through a little garden hose," Graf said.
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- The spacecraft's primary mission ends in 2010, but scientists
say it has enough fuel to last until 2014.
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