Mars Up Close

Mars Up Close

Scott Murchie's team of scientists helps uncover the secrets of the red planet

By Tom Nugent

After a 12,000-mile-an-hour descent through the Martian atmosphere, the unmanned Phoenix spacecraft settled gently onto the planet’s surface. Watching a live webcast in Maryland that Sunday evening in May, planetary geologist Scott Murchie ’81 breathed an enormous sigh of relief.

Like the elated NASA executives on the computer before him, Murchie was feeling “a whole lot of excitement and euphoria” as the tiny spacecraft deployed its solar panels and geared up for the historic excavation project that lay ahead.

As the principal investigator for NASA’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), one of the optical instruments that has been peering at the red planet from space, the former Colby geology major played a role in choosing the site (on the frigid flatlands of the planet’s arctic circle) in the months leading up to the rocket-assisted descent. Murchie, 48, spent the past year and a half studying high-tech snapshots of the Martian surface taken with a powerful camera that is aboard the U.S. space agency’s Mars Reconnaissance Orbiter (MRO).

His team of NASA optical specialists used the imaging spectrometer to look for mineral fingerprints that might have been left behind by water during the planet’s remote past. The images, and others, also were used by the team to pinpoint an ideal landing spot for Phoenix above the planet’s buried ice.

Based on powerful evidence from earlier Mars flybys, Murchie and most other space scientists are convinced that vast quantities of liquid H2O once covered portions of Mars, helping to create the environmental conditions required for life. During the next few months, Phoenix will root through the Martian soil in an effort to retrieve some of the ancient ice so that it can be analyzed for signs of microbial life from eons ago.

Armed with the high-powered CRISM and directing a team of more than 30 scientists affiliated with major U.S. universities, Murchie now is engaged in what he describes as a “truly thrilling task”—taking specialized photos that could play a key role in determining whether mineral deposits on Mars were formed in water, which could have provided habitat for life.

It was the CRISM images that helped put Phoenix on Mars. Images from the same orbiting camera (200 gigabytes worth and counting) are playing an even more central role in determining the landing site for the Mars Science Laboratory, a nuclear-powered, Hummer-sized rover that is scheduled to land on Mars in 2010. The mission: to look for preserved organic carbon and other evidence of biological processes that may have taken place on Mars in the past.

“It’s really the first time since the Viking lander [in 1976] that a lander has gone down on Mars looking for evidence of biology,” Murchie said.

Murchie helped design CRISM at The Johns Hopkins University’s Applied Physics Laboratory (APL) in Maryland, where he’s been doing planetary science since 1994. The camera can take pictures in more than 500 colors to help locate minerals that might show evidence of water in the past, says the veteran investigator. “These mineral traces are important,” he said, “because they tell us about habitability—about whether liquid water existed at some point during the past few billion years on Mars.

“We’ve taken thousands of photos of such minerals by now, and we’ve found lots of evidence—everything from clay deposits to sulfates and other mineral traces—that Mars once had the kind of environment you would need for life. That doesn’t confirm that life actually ever existed there, of course, but it does suggest that organic creatures, including bacteria and other microbes, were certainly possible.”

Murchie points out that scientists won’t know for sure until they bring some Mars rock and soil samples back to earth “and throw entire buildings full of chemistry instruments” at them. “I do think we’re getting closer all the time to answering the question of whether we’re alone in the cosmos,” he said. “As a scientist—as a human being—I think this is a very exciting time to be alive, and I can hardly wait to see where all of this space exploration is going to take us next.”

Murchie’s own scientific exploration began in his boyhood in rural Massachusetts.

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