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November
12, 2009: On Monday, NASA will begin transmitting
commands to its Mars exploration rover Spirit as part of an
escape plan to free the venerable robot from its Martian sand
trap.
"This
is going to be a lengthy process, and there's a high probability
attempts to free Spirit will not be successful," cautions
Doug McCuistion, director of the Mars Exploration Program
at NASA Headquarters in Washington.
Spirit
has been lodged at a site scientists call "Troy"
since April 23, 2009. Spirit was driving backward and dragging
its inoperable right front wheel when the rover's other wheels
broke through a crust on the surface that was covering a slippery
sand underneath. After a few drive attempts to get Spirit
out, the rover began sinking deeper in the sand trap. Driving
was suspended to allow time for tests and reviews of possible
escape strategies.
Above:
Spirit's view of its own situation. Note the circled wheel
partially buried in loose "talcum-powder-like" sand.
[more]
[larger
image]
Data
show Spirit is straddling the edge of a 26-foot-wide crater
that
had been filled long ago with sulfate-bearing sands produced
in a hot water or steam environment: map.
The deposits in the crater formed distinct layers with different
compositions and tints, and they are capped by a crusty soil
that Spirit's wheels broke through. Engineers have now plotted
an escape route from Troy that heads up a mild slope away
from the crater.
"Our
preparations to resume driving have been extensive and thorough,"
said John Callas, project manager for Spirit and Opportunity
at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We've
used two different test rovers here on Earth in conditions designed
to simulate as best as possible Spirit's predicament. However,
Earth-based tests cannot exactly replicate the conditions at
Troy."
Researchers
expect the extraction process to be long and the outcome uncertain
based on tests they've done here on Earth. "After the
first few weeks of attempts, we're not likely to know whether
Spirit will be able to free itself," notes McCuistion.
Spirit
has six wheels for roving the Red Planet. The first commands
will tell the rover to rotate its five working wheels forward
approximately six turns. Engineers anticipate severe wheel
slippage, with barely perceptible forward progress in this
initial attempt.
Spirit
will return data the next day from its first drive attempt.
The results will be assessed before engineers develop and
send commands for a second attempt. Using results from previous
commands, engineers plan to continue escape efforts until
early 2010.
 Right:
A test rover sandbox at JPL where engineers have been experimenting
with techniques for freeing Spirit. [more]
[larger image]
"Mobility
on Mars is challenging, and whatever the outcome, lessons
from the work to free Spirit will enhance our knowledge about
how to analyze Martian terrain and drive future Mars rovers,"
McCuisition said.
Even
if Spirit remains in place, it could continue making important
discoveries about Mars. The "sand trap" turns out
to be a region of great scientific interest.
"The
soft materials churned up by Spirit's wheels have the highest
sulfur content measured on Mars," says Ray Arvidson,
a scientist at Washington University in St. Louis and deputy
principal investigator for the science payloads on Spirit
and Opportunity. "We're taking advantage of its fixed
location to conduct detailed measurements of these interesting
materials." The rover's work at Troy augments earlier
discoveries it made indicating ancient Mars had hot springs
or steam vents, possible habitats for life.
Spirit
and its twin rover landed on Mars in January 2004. They have
explored Mars for five years, far surpassing their original
90-day mission. Opportunity currently is driving toward a
large crater called Endeavor.
Stay
tuned to Science@NASA for updates on NASA's efforts to free
Spirit.
Editor: Dr.
Tony Phillips | Credit: Science@NASA
| more
information |
| Spirit
and Opportunity home page -- NASA's Jet Propulsion
Laboratory manages the rovers for NASA's Science Mission
Directorate in Washington.
A
Mars Rover Named "Curiosity" -- read about
NASA's next Mars rover in a story from Science@NASA
A
Tale of Planetary Woe -- Long ago, something calamitous
happened to Mars, transforming a hospitable world into
the apparently lifeless desert we see today. Many scientists
believe the Red Planet lost most of its atmosphere,
but how? A new NASA mission named MAVEN is specifically
designed to answer that question.
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