NOVA Special Looks At The Roving Odyssey On The Red Planet

By ANN Senior Editor Pete Combs

A year after landing on Mars, the twin rovers Spirit and Opportunity continue their quest to confirm the existence of water -- and perhaps life -- on a planet that now appears so very sterile.

"You need to have the stuff from which life is made," said Cornell University's Steve Squyres, leader of the rover science team. "The one thing we know that you have to have for life as we know it on Earth is liquid water. Mars today is a cold, very dry and desolate place. Yet, there are these tantalizing hints from the pictures [taken by the Mars Global Surveyor orbiting Mars] that it was once wetter."

It's been a good year on Mars. So far, Squyres and his team at NASA's Jet Propulsion Lab in Pasadena, CA, has been able to say with authority that there once was water on Mars. That's the subject of a NOVA documentary about the rover's first year on Mars which airs Tuesday night at 2000 EST on PBS.

"I think the real striking result is from the Opportunity rover," Squyres told ANN. Opportunity landed in the Meridiani Planum, where scientists had seen orbital pictures indicating the possible presence of water.

"What we found there was evidence that long ago, there was a salty sea. Now it was probably very shallow and it was probably only there some of the time. You shouldn't be thinking 'ocean.' You should be thinking 'salt flats' and that kind of thing," Squyres said.

But where there's water, there's always the chance there's life. But Sqyres said you probably wouldn't have wanted to drink it. "It was muddy, it was salty -- very salty. It was probably acid. We've got pretty powerful clues now saying the water was [full of] sulfuric acid. It was kind of nasty stuff." And yet, he said, "It's the kind of environment that would have been suitable for some kinds of life."

Sqyres suggests the water on Meridiani Planum might have been like the water in the Rio Tinto in Spain (above). There, "the water is very, very acid," he said. "It's dissolved iron out of the rocks and there's so much iron in the water that it's a ruby red color. So I've got this picture in my mind of Meridiani long ago... of a red sea under a pink Martian sky. It could have been a very unusual looking place."

Both Spirit and Opportunity have long outlived their warranties. Both were designed to last about 90 days. It's a year later and, like the Energizer Bunny, they're still going. But that presents the JPL team with a whole new set of problems, said Squyres. "There's always something new on the horizon," he told ANN. "There's always something new on the horizon. We're far from running out of things to do on Mars.... We've worked very hard to find ways of operating these vehicles that will enable us to keep doing it for a very long period of time."

The Year Ahead On Mars

In the year ahead, Squyres said Spirit will continue to explore the Columbia Hills, where, after a long, torturous climb, the rover has found very intriguing signs that bedrock exposed by eons of wind erosion were originally formed by water.

"We're piecing that story together outcrop by outcrop, working out way up the hills. This is a big range of hills -- it's 120 meters high and we're only about 20-25 meters up into the hills so far, so there's a lot of mountaineering ahead of us and a lot of new stuff out there."

While Spirit has become the first mountaineer on Mars, Opportunity may soon take a long trip south. "If you go to the south about three kilometers," Squyres said, "there's something totally different. There's material we're calling the 'Etched Terrain.' That's sort of a descriptive term. We think those are rocks eroded by the wind. So we're hoping to go down there an explore those rocks."

They would be very different from the rocks Opportunity has already explored on the Planum. There, Squyres said, the rocks were generally blasted apart by asteroid impacts. "It's like the rocks have been put into a blender and it's kind of hard to read that record. But to the south of us, we think we see rocks that have been exposed very gently by the wind and there we think we'll find a record that will be much easier to make sense of."

Manned Mission?

Remember that Squyres is a robot guy. For the past several years, his life's work has centered on the robotic rover missions. But when you ask him if his robots can replace humans, you might be surprised at his answer.

"I think [a manned mission] is both feasible and necessary. Even I feel the best exploration, the most successful and the most inspiring exploration is going to ultimately be done by humans. I feel that anybody who would point at the success of Spirit and Opportunity as evidence that we shouldn't send humans is missing the point completely.

"I've always viewed our robots as being advanced scouts," he said. "They're scouting the way for humans who are going to go there eventually."

FMI: www.pbs.org/wgbh/nova/mars, http://marsrovers.jpl.nasa.gov/home