http://www.latimes.com/news/nation-and-world/la-sci-rover27-2010jan27,0,7278032.story
NASA's Spirit won't be roving Mars anymore With its six wheels stuck in sand and two of them no longer working, the explorer will become a fixed, immobile scientific observatory -- if it can survive the harsh temperatures of the coming winter. By Thomas H. Maugh II Los Angeles Times 1:50 PM PST, January 26, 2010 After six highly successful years of exploring the red sands of Mars, NASA's rover Spirit will rove no more. With its six wheels stuck in powdery sand and two wheels no longer working, the resilient little explorer will become a fixed, immobile scientific observatory -- if it can survive the harsh temperatures of the upcoming winter. "Its driving days are likely over," Doug McCuistion, director of NASA's Mars Exploration Program, said in a telephone news conference Tuesday. "Its contributions will continue" if it can be re-awakened after what could be a six-month hibernation during the Martian winter. If Spirit can be resuscitated, researchers will use it to attempt to answer one of their most pressing questions: whether the planet has a solid iron core or a liquid one. If the vehicle can't be revived, it will still have far surpassed scientists' original expectations and its design life of three months, traveling nearly 12 miles across the barren surface of Mars and finding strong evidence that water once altered the planet's terrain. Spirit's twin, Opportunity, is still moving across the Martian surface further north nearer the equator and on the other side of the planet, and continues to send back valuable data. Its efficiency has been degraded by a buildup of dust on its solar panels, but engineers are hoping for gusts of wind that will clear the dust. Opportunity has successfully weathered every Martian winter so far because "it is in a different thermal environment," McCuistion said, and the Jet Propulsion Laboratory team that controls it doesn't expect any troubles for it this winter. "Its environment is way more benign," he said. Spirit's problems began 10 months ago as it was driving toward a pair of volcanic features named Von Braun and Goddard in the southern hemisphere. Its wheels broke through the thin Martian crust in the area -- described as much like the crust on a creme brulee dessert -- and sank into a powdery sand unlike any the two rovers had encountered before. Breaking free proved difficult because one of the rover's six wheels had broken down three years earlier and had to be dragged along the ground. A second wheel became immobilized during the extrication attempts, leaving the vehicle with three good wheels on its left side and only one on its right. So far, the efforts to free it have resulted only in digging the wheels in deeper. About a week and a half ago, with winter approaching, the team shifted its emphasis from extrication of the rover to positioning it so that its solar panels would receive more sunlight, rover driver Ashley Stroupe of the Jet Propulsion Laboratory said at the news conference. The rovers were designed and built at the La Cañada Flintridge laboratory, and engineers have been guiding them from that location. Spirit is now sitting roughly flat on its long axis and has rolled about 5 degrees to 6 degrees to its left side. The team would like to get it at least level and, ideally, tilted slightly forward and to the right so that more of the solar panels would be exposed to the Martian sunlight, which will be coming from the north. The team has been able to move the robot a couple of inches each time it has tried, but those attempts can come only every few days because the batteries must be allowed to recharge. Within a few more weeks, even that amount of maneuvering will no longer be possible. The most likely scenario is that Spirit's power supply will get lower and lower and eventually it will shut down and go into hibernation mode until spring brings more sunshine. The question is whether engineers will be able to revive it to use that sunshine. NASA engineers expect temperatures around Spirit to fall into the minus 40s this winter. The craft was designed to operate in temperatures as low as minus 40 degrees F. and to survive temperatures as low as minus 67 degrees. "But that is with a brand-new rover fresh out of the box," said John Callas, JPL's project manager for the rovers. Spirit has been on the surface for six years and has gone through thousands of temperature cycles that include variations of as much as 150 degrees between day and night. "There is no guarantee that it will be able to survive these colder temperatures, colder than it has ever seen before," Callas said. If Spirit does survive, researchers hope to get many more scientific results from it, said Steve Squyres of Cornell University, the project's principal investigator. By tracking Spirit's radio signal precisely over a long period of time -- perhaps six months or more -- the team will be able to monitor Mars' "wobble" in its orbit. That will allow scientists to determine whether the planet has a solid or liquid core. "This is totally new science, really fundamental stuff" that can be achieved only with a stationary platform, he said. By looking around the craft for a long period of time, he added, the team will also be able to monitor how the planet's atmosphere interacts with its surface. And finally, by continuing to dig at the current site, the team will be able to characterize the soil much more thoroughly than has been achieved anywhere else on Mars. "The bottom line is, we are not giving up on Spirit," Squyres said. ================================================= George Antunes Voice (713) 743-3923 Associate Professor Fax (713) 743-3927 Political Science Internet: antunes at uh dot edu University of Houston Houston, TX 77204-3011 *********************************** * POST TO [email protected] * *********************************** Medianews mailing list [email protected] http://lists.etskywarn.net/mailman/listinfo/medianews
