Mapping out Mars

Mars rovers outlast scientists' expectations, continuing missions nearly five years later

Sue Vorenberg | The New Mexican

9/5/2008 - 8/29/08

With creaking joints and banged up motors, NASA's Mars Exploration Rovers Spirit and Opportunity are once again whirring to life after a winter slumber on the red planet.

The two rovers, which landed in January 2004, are sort of like middle-aged field geologists. Both have a touch of arthritis, but both are stubbornly refuse to quit and get desk jobs, said Larry Crumpler, a member of NASA's MER team and research curator at the New Mexico Museum of Natural History and Science.

"They're still very much capable of making new discoveries, but like old field geologists, they do have to watch it a little," Crumpler said with a sympathetic laugh.

Crumpler, who's also an associate professor of research — and field geologist — in the University of New Mexico's Earth and Planetary Science Department, has been involved in the NASA missions since before they first landed on Mars.

Originally, the two rover missions were set to end in April 2004. But to everybody's surprise, they kept going, the solar panels kept working and new discoveries have continued to come in, years after the two had been scheduled for the scrap heap.

This fall, the Spirit rover, Crumpler's favorite, could be headed for even more discoveries.

Right now, its sitting on a slab of rock on the north edge of a low plateau called Home Plate, soaking up sunlight so it can travel — despite one broken robotic wheel-like foot — south toward an interesting-looking volcanic area, Crumpler said.

As it juices up for the drive, it's also building a panoramic image, which isn't yet finished. But when it's done, New Mexicans might notice that a few of the scenic rocks in the distance have been named after local science fiction writers, Crumpler said.

"I try to sneak local names in when I can," Crumpler said. "Two of the rocks in that panoramic will be named after Roger Zelazny and Jack Williamson, both New Mexico writers."

When the rover heads south, it's likely to view a host of features it was never supposed to see, Crumpler said.

"Originally the rovers were supposed to stick to flat, nonvolcanic areas as they searched for possible evidence of biology," Crumpler said. "But now we've got a chance with Spirit to look at what appear to be volcanic vents. They're these kilometer-across giant pits with no sunlight going into them."

The site, which appears to be somewhat canyonlike, could also be home to lava tubes, which are caves formed when lava travels quickly underground.

Some scientists have speculated that because those caves are shielded from solar radiation, they could make good bases for future human missions to the planet.

"I think that's very possible," Crumpler said. "Lava tubes appear to be quite common, and many are in good shape."

Opportunity, the second rover, also hasn't finished it's work. It's also not in the best of shape, with shoulder problems that have left its robotic arm permanently sticking out.

Scientists have been exploring a crater with that rover, but because of age, they've decided to send it to a more mellow, flat surface where it can get around better, Crumpler said.

"Opportunity is going up on the plains, where we've seen patches of cobbles in what is mainly a sand sea," Crumpler said. "Nobody knows what those are, so when we get there we're going to take a closer look."

Some of those cobbles, which are fist-size and larger, appear to have been thrown long distances after space debris slammed into Mars, which could teach scientists more about the geology of that site, said Scott McLennan, planning leader of the MER team.

"Our experience tells us there's lots of diversity among the cobbles," McLennan said. "We want to get a better characterization of them."

Opportunity is slowly powering up and heading out of Victoria Crater, a site it has been exploring since last September.

That robot is showing signs that it soon could lose one of its six robotic wheels, much like Spirit already did, which was part of the reason the team decided to move it to flatter ground, Crumpler said.

On flatter surfaces, the loss of a wheel should not be a big problem, said Bill Nelson, a rover mission manager at JPL.

"If Opportunity were driving with only five wheels, like Spirit, it probably would never get out of Victoria Crater," Nelson said. "We also know from experience with Spirit that if Opportunity were to lose the use of a wheel after it is out on level ground, mobility shouldn't be a problem."

Still, beat up or not, Crumpler said he finds it just incredible that such a diversity of scientific finds continue to roll in long after the mission was supposed to end.

Last summer, only three years after the rovers were scheduled for the scrap heap, scientists made one of the biggest discoveries in the missions' histories. The Spirit rover found silica deposits and other rocks that basically resemble a hot spring on Earth, Crumpler said.

"In many ways, it was one of the most important discoveries of the mission, and it happened on like sol 1280," Crumpler said, noting that Mars days are called sols and that the original mission was supposed to last less than 100 sols.

Hot spring areas, like the one Spirit discovered, are important in the search for life on Mars because scientists think those elements could have been the building blocks of life on Earth, he said.

"It's absolutely amazing that every year we see new things that are more important than the ones we found in the past year," Crumpler said. "I think we have a lot of new discoveries to make in coming months."

Still, although the rovers have been remarkably durable, there's no knowing when they might finally break down, Crumpler said.

"All this could change overnight, any components could fail any time and it could just blip out," Crumpler said, noticing the odd parallel to human life.

But even if the rovers die, or when they die, the scientists' work won't be finished. There's a lot of data that Spirit and Opportunity have gathered that the team just hasn't had time to fully study.

And that will make them live on even longer, he said.

"We have so much data that we'll be able to say things long after the mission is over that we have never been able to say before," Crumpler said.

Contact Sue Vorenberg at svorenberg@sfnewmexican.com.