Scientists and engineers packed the auditorium at the Jet Propulsion Laboratory in La Cañada Flintridge Tuesday to hear the international science team for the Mars Exploration Rover Spirit recount the hard-won achievements of the little rover that could.
Initially intended as a three-month mission, Spirit continued gathering and transmitting scientific data from the Red Planet for six years before going silent in March 2010. In May of this year, hope for the rover’s return to service was abandoned. This week’s event was to pay tribute to this complex device.
“It’s hard to confine to normal words what you feel working on something like this,” said John Callas, manager of JPL’s rovers project. “I feel very privileged.”
Callas introduced team members who, one by one, shared a piece of the unfolding drama of obstacles overcome that led up to Spirit’s discovery of water-altered rocks and carbonates — evidence of a history of water on Mars.
Eighteen days after a successful landing at the appointed Gusev site in January 2004, the team faced its first obstacle, which is known as the Day 18 memory anomaly. Spirit went silent for three days.
“Spirit was not an easy-going rover,” said Charles Elachi, director of JPL. “But like a young kid that you have … sometimes they get a little bit testy, but then after, they are all nice and you give them a big hug.”
In a troubleshooting feat, the team detected the software error causing Spirit’s unresponsiveness and regained control of the rover, ready to study the rock specimens of Gusev crater.
“We went to Gusev crater,” said Steve Squyres, principal Investigator, “hoping to find layered sedimentary rocks laid down billions of years ago in a Martian lake … but then we looked at the rocks.”
Squyres and his team concluded that they were looking at plains of volcanic rocks, not the sedimentary rock they had anticipated. This was the equivalent of a second setback. One hundred Martian days into its mission, the team decided to send Spirit exploring a range of hills two kilometers to the southeast whose rocks may have come from an earlier time.
What began as a three-month geological experiment looking for evidence of water unfolded into a six-year, 4.77-mile odyssey exploring the Columbian Hills the rover scientists named in honor of the Columbia Space Shuttle.
Roving down the backside of the Columbian Hills, Spirit experienced the third setback — the right front wheel failed. Again, the rover team solved the problem by learning how to drive Spirit backwards, dragging its lame wheel.
“This rover really has a human aspect to it,” said Oded Ahronson, member of the rover science team. “There’s a lot of people in this room that have contributed to designing it and building it and driving it, but I think this rover really affected us.”
Driving backwards, dragging its failed wheel, Spirit inadvertently exposed a pure form of opaline silica while exploring a site the team named Home Plate. Opaline silica is an indication of wet environments on ancient Mars that may have supported microbial life.
“My fondest hope, for the legacy of Spirit,” said Squyres, “is that somewhere there are young people, kids, who watched the Spirit landing and who heard the scientific discovery of hot springs on Mars and looked at that and said to themselves, ‘that’s pretty cool, but I think I can do better.’”
Spirit’s rover twin, Opportunity, is still exploring the Martian landscape seven years into the original three-month mission.
“Mars is no longer this distant, alien, unknown world,” said Callas, “It is now our neighborhood and we go to work their everyday. Well done, little rover. Sleep in peace.”