NASA's Spirit Rover Completes Mission on Mars

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Feature: 2011-160 May 25, 2011

NASA's Spirit Rover Completes Mission on Mars

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-160&cid=release_2011-160

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@jpl.nasa.gov

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