In this picture of Home Plate, taken by the HiRISE camera onboard MRO, you can easily see the stark white figure that is Spirit to the left (west) of the geologic formation in this image color processed by Stuart Atkinson. "If you look carefully you can actually see bright trailing leading to Spirit - this is the result of the (right front) broken wheel being dragged through the dirt, unearthing brighter material beneath," he points out. For more of Atkinson's enhanced images and poems, check out his blog, Road to Endeavour.
“As I’ve learned more in fieldwork in exotic places and in lab work, that discovery is becoming clearer to me, and the different questions that remained after the finding are now being answered with a decade of follow-on work,” said Ruff. “The story of an ancient hot spring producing this rock called Silica Sinter is really quite robust now.”

Interestingly, the story has turned into something of a hunt for potential biosignatures as a result of that follow-on research. Most recently, Ruff and colleague, ASU Professor Jack Farmer, conducted fieldwork at El Tatio, a high elevation hot spring system in Chile that “opened up the possibility that the silica at Home Plate may actually feature structures that could be stromatolites produced by a combination of geology and biology,” Ruff said.

“Spirit's unexpected discovery of concentrated silica deposits was one of the most important findings by either rover,” Squyres declared then. “It showed that there were once hot springs or steam vents at the Spirit site, which could have provided favorable conditions for microbial life.”

As Arvidson summed it up this past month: “In the end, 20 years from now, the overall set of deposits associated with Home Plate and the likely discovery hot spring deposits is the science discovery for which Spirit will be remembered.”

Meanwhile, as Spirit continued research on the silica near Home Plate, the dust in the atmosphere was getting thicker. By July 2007, the regional dust storms that were turning the skies an opaque dark rusty red merged into a monster, planet-circling storm. Although both rovers were feeling the effects Spirit, Opportunity was literally in the dark. NASA estimated that 99% of direct sunlight was blotted out over Meridiani, leaving only the limited diffuse sky light to power the rover.

“We were spacing the downlinks from Opportunity to once every four sols in order to conserve energy,” remembered Herman. “Every time you downlink data it takes energy and we didn’t want to deplete any more power than we had to. The sky was dusty and the energy was low, and the rover was getting cold. We got our downlink, sent up a plan – and then we waited. Everyone thought Opportunity was going to die.”

Time passed. Slowly. But it did pass. On the appointed morning, Herman settled in behind her console in Mission Control with probably 10 or 15 people standing behind her. Squyres, then on sabbatical at Caltech, was there on site. Everyone was waiting to see if Opportunity had survived.

Finally the rover’s telemetry appeared on Herman’s monitor. “’We’re still alive!’” she said. “And the rover was actually improving. We were so happy. We all hugged. I cried. It was really, really wonderful.”