Engineers Bring Mars Rover Out of Its Shell
NASA’s Spirit rover has completed a “reverse robotic origami,” unfolding itself from its flight configuration in preparation for rolling off the lander about midnight Tuesday, much earlier than engineers had predicted just a day ago.
The rover “now stands at full height, and all six wheels are in their final position and ready to drive,” said Jennifer Trosper, mission manager at NASA’s Jet Propulsion Laboratory in Pasadena.
The 4-foot-9-inch rover was folded into a compact form so that it would fit into the tetrahedron-shaped lander. Unfolding it on Mars was “the most complex sequence of deployments that has ever been done on a robotic spacecraft,” said Chris Voorhees, a mechanical systems engineer at JPL who devised the maneuver.
To allow the rover to stand up, 12 pyrotechnic devices had to fire, nine motorized mechanisms had to work and six structural latches had to be engaged, he said. Everything went perfectly, and “she is asleep right now and resting on all sixes,” he added.
Saturday evening, engineers planned to move the instrument arm from its folded flight position to make it ready for travel on the surface. The team then plans to fire a pyrotechnic device today to sever the last cable connecting the rover to the lander, readying Spirit for roll-off.
At that point, Trosper said, “the lander becomes space debris.”
The rover will spend the better part of Monday night pivoting 120 degrees to the right on the lander so that it can drive off on a secondary ramp.
The primary ramp, which would have allowed it to exit by driving straight ahead, is partially blocked by one of the collapsed air bags that cushioned the raft’s landing last Saturday.
Mission engineers tried a simulated roll-off in their “sandbox” laboratory in Pasadena on Friday and concluded that there was a small chance that the rover’s solar panels would brush against the bag if it tried to drive straight ahead.
“That’s not really a place we want to be in,” Trosper said. “We don’t want to get the solar panels caught on an air bag.”
Trosper said Spirit had transmitted more than 200 megabits of data to Earth overnight Friday, “10 times more than Pathfinder had the capability to do.”
That data included another high-definition color picture from the panoramic camera, this one looking to the southwest. The team hopes to have the entire 360-degree panorama transmitted to Earth “pretty darn soon,” JPL geologist Matt Golombek said.
The images obtained so far show that about 3% of the site is covered by rocks, substantially less than the 20% at the landing sites of the three previous missions to Mars, Golombek said. “It is also smoother and flatter than at least two of the three other landing sites, and it is less dusty as well,” he said.
A second JPL team is studying the data from Spirit in anticipation of the landing of the second rover, Opportunity, scheduled for Jan. 24.
The scientists concluded that their predictions of the Martian atmosphere at the time of Spirit’s descent matched reality quite well, “and that gives us confidence that we can use the same model for Opportunity,” said JPL’s Joy Crisp, a mission scientist.
Opportunity is supposed to land on the opposite side of Mars from Spirit, in Meridiani Planum, a dark-gray, basaltic plain that is substantially different from any of the sites previously visited.