JPL scientists announced this week that they have given up attempts to regain contact with the Mars rover Spirit, which powered down in March 2010 after becoming stuck in loose soil on the southern hemisphere of the Red Planet.
The last of more than 1,300 unanswered command signals hoped to reawaken Spirit was sent into space at 12:04 a.m. Wednesday, said JPL Mars Exploration Rovers Project Manager John Callas.
Many factors went into the decision to end Spirit’s mission, including the need to preserve Mars relay orbiters in top condition for November’s anticipated launch of the new rover Curiosity, a plummeting probability for success, and the fact that “even if we heard from her today, there would so little energy, we couldn’t do the science objectives we wanted to do,” he said.
Still, Wednesday was a sad day for Callas, who first went to work on Spirit and its twin rover Opportunity more than 10 years ago, long before their 2004 arrival on Mars for three-month missions that unexpectedly stretched out over many years.
“These rovers are very different from any other interplanetary spacecraft, Callas said. “We really have a strong bond and attachment to them. They exhibit such humanlike qualities — responsive, dutiful, accomplished, intrepid. They take our instructions, carry them out and tell us what they’ve learned. And they have eyes to see and an arm to reach out and touch the soil, many of the characteristics of how a human would interact on Mars. They really are our ambassadors, our proxies, on Mars.”
During its extended-life mission, Spirit managed some of the most significant discoveries ever on extra-terrestrial soil — sometimes serendipitously.
When Spirit’s right front wheel locked up in 2007, scientist were forced to drive the rover backwards, only to discover that dragging the wheel was cutting a groove in Martian soil and exposing unexpected silica deposits — proof that “not only was there once water on Mars, but there also was a [hot-spring-like] energy system that could drive an ecosystem. If the wheels were fine, we would have driven right past,” Callas said.
Spirit also discovered carbonate deposits that suggest Mars rocks had sequestered an ancient atmosphere. Even the loose soil that trapped Spirit became evidence that water flowed there as recently as a million years ago, much later than previously thought.
Opportunity, meanwhile, is heading toward a crater that appears to contain clay that might have preserved whatever organic compounds existed there in the past, part of a search for the foundations of life that Curiosity will continue.
“In addition to all the discoveries Spirit has made, Spirit has given us a great intangible — that is that the rovers have made Mars a familiar place. It is no longer a strange, alien world,” Callas reflected. “Mars is now in our neighborhood.”