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A geologist's mission to Mars

Science team member John Grotzinger put aside his earthly research to help direct long-term planning for NASA's Mars rover missions.
John Grotzinger watches video of a rover practice session during a news briefing this month at NASA's Jet Propulsion Laboratory.Ric Francis / AP file
/ Source: Special to

There is a little rock on Mars, just a few inches high and pointy at the top like a tiny mountain, called Adirondack. John Grotzinger named it. And there are pictures of Adirondack we can all see back here on Earth, thanks to the cameras on the Spirit rover. John Grotzinger had a lot to do with the decision to take those pictures.

On the other side of the Red Planet, the Opportunity rover is getting ready to roll off its platform and over to a nearby small ridge. Grotzinger will play a key role here, too. Among the hundreds of scientists working at the Jet Propulsion Laboratory on the Mars mission, Grotzinger is the sedimentologist, an expert in rocks that build up in layers, often layers deposited by water.

Images taken by Opportunity show regular lines in the 18-inch (45 cm) high ridge, suggesting the rock is sedimentary. If investigations by Opportunity in the days to come determine that the rock is layered, and that water -- as opposed to wind or volcanic activity -- laid down those layers, than Grotzinger will be a key part of the science team that announces one of the great discoveries of modern science, the distinct possibility of life “out there.”

From the Arctic to Mars
It’s a long way from the Arctic, where Grotzinger, a geologist at the Massachusetts Institute of Technology, did his first field work more than 20 years ago.

“That was the ultimate romance. In the Arctic three months a year, just five of us hacking at rocks and taking samples, covering a lot of ground, making maps, ” Grotzinger says, just a bit wistfully. And yet, it’s not such a long way from what he did in the tundra to what he’s helping direct now more than 120 million miles away.

As one of the leaders of the long-term planning group for the Spirit mission, Grotzinger is helping to decide where the rover will go and what scientific experiments it will conduct as it explores the Gusev Crater on Mars.

“Being in this position now is a natural match with my early experience in all that open territory,” he says. “My natural tendency is to roam, to get the complete context in which observations are being made, then go back and get details.”

Grotzinger and his planning team meet three times in the course of each "sol,” or Martian day, which is 39.5 minutes longer than the Earth day.

“Our job is to talk about science ideas, to consider what we’ve learned in the mission so far and what we’re learning, to step back and look at where we stand, and consolidate ideas about what we should do next,” he says.

“We don’t want to just go from one rock to another and get caught up in the excitement of each day and each new discovery. I have to prevent day-to-day curiosity from interfering with our long-term scientific objectives. Our job is to help focus the thinking of the science planning. It leads to decision-making about where rover goes, and what kind of science it will do.”

In addition to telling the rover’s “drivers” exactly where they should send the golf cart-sized robot, Grotzinger and his fellow team members have to consider how much time and electrical power it will take for Spirit to get there. They also must consider how much time and energy Spirit will take to do certain experiments and how much information will have to be stored in the rover’s memory before it can be uploaded to the Mars Odyssey or Mars Global Surveyor spacecraft for relay back to Earth. And they have to figure out which locations and what kinds of experiments are likely to reveal the most important information.

Then they have to pack all that into a mission schedule of 90 sols, at a rough cost of $4 million per sol, and balance the demands of science team members who include atmospheric physicists, mineralogists, climatologists, mineral spectroscopists and a lot of other ‘”ists.”

“It’s all very collegial,” Grotzinger says. “Everybody listens to everybody else’s ideas for what kind of science makes sense. Still, we can’t do what everybody wants. What our small committee does is constantly remind everybody that this is a mission to look for water. That prevents any one discipline from arguing for their own narrow focus too much.”

So does the rule laid down by the mission's overall science director, Cornell University's Steve Squyres, that anybody who suggests an idea that turns into an experiment can be a co-author on the paper about that experiment, regardless of their field of expertise. That encourages teamwork, because publication is an important career builder for scientists.

The science moves more slowly on Mars than on Earth: It can take days to conduct a handful of experiments on just one small specimen.

“Sometimes I think, ‘This is nuts,’” Grotzinger says. “I want to just walk over there and use my hands. It’s very frustrating. If this was on Earth we could take care of some of this stuff in two or three days.

“But it’s a tradeoff, too,” he says. “There is no field geologist on Earth who goes out with a panorama cam with eight high-quality filters from infrared to ultraviolet, and pocket-sized mass spectrometers, and miniature thermal emission spectrometry, and microscopes and all this gear.”

On a high during down time
It is midafternoon in Pasadena, but night on Mars and down time for most mission scientists. Grotzinger slouches casually in the media room on the JPL campus. Behind him, a TV monitor silently replays video of various parts of the mission: a rocket blasting off, interviews with officials, computer animations of Spirit chugging around on Mars. We ignore it.

But when a line of dirt-covered rock appears on the screen, Grotzinger quickly stands and goes over to the screen, and the few remaining journalists in the room become his students as he excitedly starts to point at the screen. He is describing features on the ridge of rocks that Opportunity has imaged. These rocks could be some of the most important rocks ever found. The excitement rises in Grotzinger’s voice.

“See these lines over here, where it looks like some of the layers intersect at an angle with the lines of these other layers?” he asks. “Those are significant indications of cross bedding, where the layers don’t all run at the same angles.”

Cross bedding, Grotzinger explains, means the layers were laid down at different times by different directions of flow of whatever was carrying the sediment that formed the layers. It could have been the wind, if the particles were small enough. It could have been volcanic ash. And it also could have been water.

“That’s what I think it is,”  he says with a gleam, “sedimentary rock formed by flowing water.”

“But we can’t start jumping up and down,” he quickly adds. “We have to work through it slowly. Do it right.  Careful science. Develop hypotheses. Design experiments to test and falsify those hypotheses.”

Oman vs. Opportunity
Two years ago, Grotzinger was spending a good chunk of his time in the deserts of Namibia and Oman. Pipeline excavations were revealing layers of sedimentary rock embedded with fossils from the pre-Cambrian era, a period 540 million ago when there was an explosion of life forms on the planet that gave rise to all the animals alive on the Earth today. It is one of the best places on the planet to do geobiology, which combines geology, biology and a little paleontology to unravel the origins of life. Geobiology is Grotzinger's passion.

“We were in the middle of major phases of discovery. I dropped that to do this work,” he says.

He admits he's had doubts since, as he split his time between his family back in Massachusetts and his work in Pasadena.

“If we were to go from rock to rock to rock and all we found were different kinds of basalt (volcanic rocks), we wouldn’t learn that much. ... It’s a hell of a commitment if it comes to nothing. I thought about that.”

But those doubts have been erased, in part by the emotional intensity of the past few weeks. First there was the elation of the successful landing and deployment of Spirit. Then, days later, just as Spirit was out on Martian soil and beginning to use its geologic instruments, it suddenly stopped working.

“It was just terrible,” Grotzinger recalls. “We were sitting there just a few sols before the landing of Opportunity, at this moment of great anticipation of another success at another location. And then you have to deal with this black cloud.”

Computer engineers figured out Spirit’s problem before its batteries went beyond the point of no return. That rescue also revived the hopes of Grotzinger and the Spirit team.

“What they did in resurrecting Spirit is phenomenal. Incredibly brilliant,” he says. “They work like dogs. And they are so cool under pressure. I’ve worked at MIT for a long time, around lots of engineers I never really interacted with much. Nothing I’ve ever done has come close to the feeling I’ve got about engineers now.”

Nor has any science he’s done matched this work, he says.

“It’s incredible. It’s changed my life.  I’ve never done anything like this before. We geologists work in the field, usually alone or with a couple students or colleagues. Here we interact with and benefit from 50 other people, literally minute by minute.”

Oh, and there is that small matter of being a key member of a team that may well establish the plausibility of life on another planet.

“I feel so lucky to be a part of this," Grotzinger says. “There’s nothing like it.”