[meteorite-list] NASA's Spirit Rover Completes Mission on Mars

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.cfm?release=2011-160  

NASA's Spirit Rover Completes Mission on Mars
Jet Propulsion Laboratory
May 25, 2011

NASA has ended operational planning activities for the Mars rover Spirit
and transitioned the Mars Exploration Rover Project to a single-rover
operation focused on Spirit's still-active twin, Opportunity.

This marks the completion of one of the most successful missions of
interplanetary exploration ever launched.

Spirit last communicated on March 22, 2010, as Martian winter approached
and the rover's solar-energy supply declined. The rover operated for
more than six years after landing in January 2004 for what was planned
as a three-month mission. NASA checked frequently in recent months for
possible reawakening of Spirit as solar energy available to the rover
increased during Martian spring. A series of additional re-contact
attempts ended today, designed for various possible combinations of
recoverable conditions.

"Our job was to wear these rovers out exploring, to leave no unutilized
capability on the surface of Mars, and for Spirit, we have done that,"
said Mars Exploration Rover Project Manager John Callas of NASA's Jet
Propulsion Laboratory, Pasadena, Calif.

Spirit drove 4.8 miles (7.73 kilometers), more than 12 times the goal
set for the mission. The drives crossed a plain to reach a distant range
of hills that appeared as mere bumps on the horizon from the landing
site; climbed slopes up to 30 degrees as Spirit became the first robot
to summit a hill on another planet; and covered more than half a mile
(nearly a kilometer) after Spirit's right-front wheel became immobile in
2006. The rover returned more than 124,000 images. It ground the
surfaces off 15 rock targets and scoured 92 targets with a brush to
prepare the targets for inspection with spectrometers and a microscopic
imager.

"What's really important is not only how long Spirit worked or how far
Spirit drove, but also how much exploration and scientific discovery
Spirit accomplished," Callas said.

One major finding came, ironically, from dragging the inoperable
right-front wheel as the rover was driving backwards in 2007. That wheel
plowed up bright white soil. Spirit's Alpha Particle X-ray Spectrometer
and Miniature Thermal Emission Spectrometer revealed that the bright
material was nearly pure silica.

"Spirit's unexpected discovery of concentrated silica deposits was one
of the most important findings by either rover," said Steve Squyres of
Cornell University, Ithaca, N.Y., principal investigator for Spirit and
Opportunity. "It showed that there were once hot springs or steam vents
at the Spirit site, which could have provided favorable conditions for
microbial life."

The silica-rich soil neighbors a low plateau called Home Plate, which
was Spirit's main destination after the historic climb up Husband Hill.
"What Spirit showed us at Home Plate was that early Mars could be a
violent place, with water and hot rock interacting to make what must
have been spectacular volcanic explosions. It was a dramatically
different world than the cold, dry Mars of today," said Squyres.

The trove of data from Spirit could still yield future science
revelations. Years of analysis of some 2005 observations by the rover's
Alpha Particle X-ray Spectrometer, Miniature Thermal Emission
Spectrometer and Moessbauer Spectrometer produced a report last year
that an outcrop on Husband Hill bears a high concentration of carbonate.
This is evidence of a wet, non-acidic ancient environment that may have
been favorable for microbial life.

"What's most remarkable to me about Spirit's mission is just how
extensive her accomplishments became," said Squyres. "What we initially
conceived as a fairly simple geologic experiment on Mars ultimately
turned into humanity's first real overland expedition across another
planet. Spirit explored just as we would have, seeing a distant hill,
climbing it, and showing us the vista from the summit. And she did it in
a way that allowed everyone on Earth to be part of the adventure."

JPL, a division of the California Institute of Technology in Pasadena,
manages the Mars Exploration Rovers Opportunity and Spirit for the NASA
Science Mission Directorate, Washington. For more about the rovers, see:
http://www.nasa.gov/rovers and http://marsrovers.jpl.nasa.gov.

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

2011-160