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Needles and Martian Haystacks

John Grotzinger

John Grotzinger '79

by Cynthia L. McVey

John Grotzinger '79 has the distinction of being the Mission Leader and Project Scientist responsible for planning the Mars Science Laboratory, which launched the Mars Curiosity Rover in November, 2011. Given his position today, it's hard to believe his first application to NASA in 2003 was somewhat of, as he says, a "Hail Mary."

An eminent sedimentologist and stratigrapher, Grotzinger is the Fletcher Jones Professor of Geology at the California Institute of Technology. At the time he prepared his proposal to be included on the Mars Orbiter mission, he had just completed a sabbatical working in Oman, helping the Oman Oil Company find oil and gas in a unique geological setting. His personal mission during the trip was to search for organic molecules.

"The field has evolved from one that looks for direct signs of life, such as conventional fossils, to looking at the chemistry of rocks and finding out if they contain complex organic molecules that are less direct signs of life," explains Grotzinger.

He says searching for organic molecules in Oman put him in the right position to lead the mission on Mars. When he submitted the proposal, however, the correlation between the two projects was more of a hunch.

"At the time, most people viewed Mars as a planet made up of volcanic rock," he says. "I wrote my proposal taking the gamble that sedimentary rocks - those in which 99 percent of the record of life on Earth are preserved - would eventually be found on Mars."

Soon after submitting, a Mars orbiter reported data indicating this might just be the case and Grotzinger was selected as the only sedimentologist on the team.

When the rover Spirit landed on Mars in 2004, Grotzinger spent three months waiting while the vehicle turned up no additional signs of sedimentary rock. Spirit's twin, Opportunity, appeared to hold the same fate until one sol (a Mars day), it sent back images of something different. Grotzinger says he and a paleontologist were the only two people in the room who knew what it was.

"We just looked at each other, 'Oh, my God. Is that really a sedimentary rock?'" he says. "My next thought was, 'Okay, I've got something to do here."

The newest rover, Curiosity, will land on Mars in August 2012. Its mission is to detect organic compounds that may point to the one-time existence of life on Mars. But Grotzinger is keeping his expectations in check.

"Even on Earth, a planet teeming with life, it's not easy to find organic compounds because preservation is very finicky. On Mars, detecting organic compounds is more than a needle in a haystack," he cautions.

The promise, he explains, is in what they can learn if all goes well. Gale Crater, the landing site on Mars, is a mountain more than 15,000 feet high with layers of sedimentary rock.

"Researching those layers from the bottom to the top is like reading a book, beginning to end," says Grotzinger. "We don't know what story it will tell, but I expect it will be about the long-term environmental evolution of Mars."

This will help scientists understand the historic divergence of Earth and Mars. Early Mars was very much like Earth, but became cold, dry and inhospitable. "What happened?" asks Grotzinger. "We can get a better perspective of our own ancestry and the evolution of life on Earth by comparing it to how Mars set out on its own direction."

In his own evolution as a scientist, Grotzinger gives much credit to his time at Hobart and an independent research project in geology. While looking for sources of sodium entering Seneca Lake, Grotzinger says two hypotheses led to community sources as polluters, while a third was based on natural causes - glaciers scraping the surface down to the salt layer as they formed the lake.

"What I found most interesting was the relationship between how a social problem related to an extraordinary event in the history of the Earth," he says. "This experience led directly to my chosen field. I wanted to work on things for which the textbook hasn't been written."

Exploration of Mars fits that bill quite nicely.

Grotzinger explains, "Only with the exploration of Mars will I be able to participate in research where we set down a rover and look at a rock and have no clue what to expect."