Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 90 of Spirit's mission to Gusev Crater at approximately 14:12:29 Mars local solar time, camera commanded to use Filter 2 (753 nm). NASA/JPL/Cornell
Posted on 04/05/2004 7:35:24 PM PDT by NormsRevenge
PASADENA, Calif. -
NASA (news - web sites)'s Spirit rover wrapped up its primary mission to Mars on Monday as it continued to roll across the planet's surface on an extended tour that could last through September.
The unmanned robot, marking its 90th full day on Mars, had accomplished all of the tasks NASA considered essential to declare the joint mission a success. Its twin rover, Opportunity, was getting close to achieving the same.
"Spirit has completed its part of the bargain, and Opportunity doesn't have much left to do," said Mark Adler, manager of the $820 million mission.
The mission's key tasks included a requirement that one of the rovers travel at least 1,980 feet — a mark Spirit surpassed on Saturday.
Between the two of them, the rovers also had to take stereo and color panoramas of their surroundings, drive to at least eight locations and operate simultaneously for a minimum of 30 days.
NASA assumed technical and other problems would ground the rovers fully one-third of the time they operated on Mars.
Despite computer memory problems that left Spirit sidelined for 2 1/2 weeks, it has still spent more days at work than expected. Opportunity must function for another 20 days before meeting all its goals, Adler said.
"It's better than we could have possibly imagined," Adler said.
NASA has extended the mission through September. If the rovers continue to function, the Jet Propulsion Laboratory will apply for money to extend the project again, Adler said.
Beginning Thursday, NASA will begin updating software on the rovers. The new software should allow Spirit to travel farther each day while navigating autonomously and help Opportunity conserve battery power at night.
Spirit landed Jan. 3 in Gusev Crater, a 90-mile-diameter depression scientists believed once contained a lake. It is now several days into a trek toward a cluster of hills that may contain geologic evidence of a wetter environment, including perhaps layered rocks formed in standing water.
Opportunity has found such rocks halfway around the planet since landing Jan. 24. Scientists believe a salty sea or swamp once covered that site, called Meridiani Planum.
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On the Net: http://marsrovers.jpl.nasa.gov/home/index.html
Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 90 of Spirit's mission to Gusev Crater at approximately 14:12:29 Mars local solar time, camera commanded to use Filter 2 (753 nm). NASA/JPL/Cornell
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Right Panoramic Camera Non-linearized Full frame EDR acquired on Sol 70 of Opportunity's mission to Meridiani Planum at approximately 15:49:09 Mars local solar time, camera commanded to use Filter 1 (436 nm). NASA/JPL/Cornell
Actually I don't believe most of these depressions on the Meridiani plains are impact craters. I suspect they represent a kind of sinkhole.
Note the light colored rock protrusions similar to the layering back at the crater. It would appear that much or all of Meridiani is made of this light sedimentary rock, and the hematite sand/gravel covers it (except at Endurance Crater where we are going to have a sedimentary geology field day when we get there).
Where the rock was weak and had voids it has collapsed creating the depressions and exposed outcrops. On Earth sinkholes are created in a similar way. Water dissolves limestone substrate creating voids and caverns. Where the void approaches the surface, the week layer then collapses.
I'm not suggesting there is water there now, but the mechanism could have created these Martian sinkholes eons ago.
My guess is that they are going to take the driving a little slower. I bet they will also avoid these little craters for fear of causing any crumbling or collapse that could be disastrous for the MER Rover since it doesn't come equipped with a roll-bar.
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