By September 2007, Opportunity had shaken off the dust from the planet-circling storm just a couple months earlier as best she could and was ready to begin her detailed study inside Victoria Crater. “The most stressful, memorable moment was on the rover’s Sol 1291 (September 11, 2007) when we did the toe-dip into Victoria,” said Rover Planner Paolo Bellutta, who had been assigned the tasks of defining and charting the best entry and egress points. Although he was nervous, the rover cruised in and around Victoria—and out again.
Over at Gusev, Spirit spent most of 2008 surviving. First, there was the mission’s third Martian winter to get through. The rover managed to clear it by parking right on the edge of Home Plate, her arrays to the north and the winter Sun, conserving energy and waiting out the brutal cold.
Her odds for survival seemed to improve significantly in April 2008 as the dusty skies cleared dramatically over at Gusev, enabling the robot to maintain better-than-anticipated power levels that month. And that meant the engineers "probably won't have to do anything extraordinary" to keep her alive, then-MER Chief of Rover Engineering Jake Matijevic said at the time. But there were still months to go before the Martian spring.
Then in November 2008, a dust storm struck the ‘bot dead on and dropped her energy levels to 89 watt-hours, the lowest recorded on the mission. But on November 13th, the rover phoned home. “It was a good day on Mars today,” Squyres told The MER Update then.
Arrays thick with dust, Spirit survived both winter and another dust storm and finished her tour of the top of Home Plate. Then she drove off the mound, ultimately heading for the next destinations.
By April 2009, she was cruising along the western side of the circular mound, on the way to the next target destinations to the south named after rocket pioneers Robert Goddard, and Wernher Von Braun. Suddenly, while driving along Home Plate the rover caught the edge of a small crater hidden by the sand that filled it and was stuck. By early May, it was clear her left wheels were seriously dug in. After months of research on Earth, in November 2009 the team began sending commands for the rover to begin extricating itself.
When the first extrication strategy failed, the team switched to Plan B and by late January 2010 Spirit was beginning to make real progress. But the onset of winter brought the rover to a stop. Unable to move to a Sun-facing slope, she was forced to shelter in place.
Spirit downlinked a communiqué on March 22, 2010. Shortly after that, the ops engineers assumed the rover tripped the low power fault and went into a hibernation mode, to rest and try to collect enough sunlight to keep her survival heaters available and the mission clock running. That’s what the rover was programmed to do.
