As it silently sits in Gusev Crater, NASA’s Spirit Mars rover is frozen in time. It holds in its memory files unique data that can help unlock the secrets about Mars rocks and the planet's atmosphere, including a rare combination analysis completed with the help of the European Space Agency's Mars Express.
Last Wednesday, Spirit was preparing to run its rock abrasion tool, or RAT, a grinding device that removes dust and weathered rock, on the exposed fresh rock "Adirondack" when the robot came to a screeching halt. The leading theory is that the robot suffered a breakdown in software that controls file management of its memory.
Right now, Ron Greeley, a Science Operations Working Group chair for the rover effort from Arizona State University in Tempe, and others in his group are trying to figure out what data could be in memory, and of those data, what’s the prioritization.
"We’ve been looking at what are the things that we want to get back. There are some things that are unique data [that] we’ll never have a chance to get again," Greeley said.
"We’re working through what might be in memory, " said Greeley. "So if there’s any choice, we want this first, then this, then this … and work down the list that way."
Mars Express and Spirit data
Held tight in Spirit’s memory software are choice science products. That library of knowledge includes first looks at the Adirondack rock using the Mössbauer spectrometer and alpha particle X-ray spectrometer, called the APXS for short.
When Spirit is brought back to health, scientists want to move ahead and use the RAT on Adirondack. But the pre-RAT spectrometer data is important for before-and-after comparisons. So that data set is a very high priority, Greeley said.
Both the Mössbauer spectrometer and the APXS units have built-in memory. But that information is relayed through Spirit’s central brain control. These instruments could be re-queried, but it would take many hours to regain the same data that could be lost.
But Greeley also pointed out that a unique set of data onboard Spirit involves the overhead pass of Europe’s Mars Express. There was coordination of Spirit looking up while Mars Express instruments looked down on the site. Doing so would give scientists a one-of-a-kind profile in time of atmospheric particles in the Gusev Crater region, he said.
"There’s nothing absolutely critical," said Cornell University's Jim Bell, payload element lead for the rover panoramic camera. "If they have to pull the plug … so be it … if we need to do that to move on. Maybe the worst hit would be those measurements taken during the Mars Express overflight. We were taking data the same time they were.
"We got back the little thumbnails [of data], but we didn’t get back many of the big full-frame images from that sequence. And that can’t be repeated until the next time that spacecraft flies over. But if that’s the worst, that we lose some of that data, it’s not going to affect mission success," Bell said. "We don’t want to lose any data of course."
Spirit in rehab
Things are progressing well here at JPL in trying to regain Spirit’s sensibility.
Troubleshooting is going on around-the-clock, said Jennifer Trosper, JPL’s rover mission manager. It could be two to three weeks of work before Spirit is back in a driving state, she said Monday at a morning press briefing.
From its early flat-lined medical condition, Spirit is now in rehab, Trosper said.
Too many memory files, too many tasks being fulfilled, and not enough deleting of less-needed data appears to have conspired to upset Spirit.
"For this mission to be successful, a lot of things have to happen at the same time," said Bell. "There were 18 days in a row of this ballet of the engineers, the scientists, the data management people and the software people — all working together juggling everything."
Bell said he doesn’t think Spirit’s situation was brought about by overworked or tired personnel, or somebody hit the wrong button. "I don’t think that’s the situation," he said.
Also locked within Spirit’s memory are older panoramic camera shots when Spirit still sat on its lander. There are some pieces of a horizon panorama, too, and pictures of the robot’s arm deploying science instruments.
Spirit has already delivered an amazing legacy of scientific data, with by far the best images and spectra ever obtained for another world," said James Garvin, NASA lead scientist for Mars exploration within the Office of Space Science in Washington.
"I am literally speechless over what it has achieved in only 18 sols of science operations, intermixed with many steps to get moving on the real Mars. And over the next weeks to months, I am confident the MER science team will uncover some of the mysteries of Mars, from the nature of the soils … to the basic chemistry and mineralogy of local materials," Garvin told Space.com.
"I believe that our team will get Spirit moving again, doing science and delivering on its promise," Garvin said. "We have only begun to fight the ‘deep-space gremlins,’ and Spirit will be back in business."