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Science: NASA’s power couple comes to dinner
By Jason Lesley
Dr. David Crisp’s head is in the stars; Dr. Joy Crisp’s feet are firmly on the ground. Together, they are NASA’s power couple, orchestrating missions in space and on Mars from the Jet Propulsion Lab near Pasadena, Calif.
The Crisps spent Thanksgiving with friends Rob and Susan Polack of the Oak Lea community, happy to get a few days away from their intense work schedules. The couples met snorkeling in the Caribbean over a Thanksgiving holiday about a dozen years ago and got to be travel buddies. Rob Polack and the Crisps are all graduates of Princeton University. “You could spend hours listening to both David and Joy talk about the sky,” said Susan Polack. “It’s magical.”
David and Joy Crisp live in La Cañada, Calif., within walking distance of NASA’s Jet Propulsion Lab. They work long days, directing hundreds of scientists and engineers and when the seasons allow they like to walk to work and decompress on the walk home.
“We’ve been at this business for quite awhile,” David said. “I am truly a graybeard. We know we will have to give it up. The pace is unsustainable. That’s what it takes to make pioneering discoveries. These jobs are intellectually stimulating but at the same time exhausting.”
While the Crisps were visiting, his team was informed by the U.S. Air Force that it would have to change the orbit of a satellite to avoid a collision with some space junk. They moved it 150 meters up and had to start bringing it back down last Friday. That satellite flies in a precise orbital pattern with five others. “I had perfect alignment,” David said, “and we just blew it.”
Since receiving his Ph.D. from the Geophysical Fluid Dynamics Program at Princeton in 1984, David’s research has focused on the development of remote sensing and climate models of Venus, Mars and Earth. In his latest mission, David is concentrating on this planet as the leader of NASA’s Orbiting Carbon Observatory-2. The mission is designed to make precise global measurements of atmospheric carbon dioxide by satellite. It’s not enough to provide the data, he said, it must be interpreted and put in context in order for governments to do policy-making. He was scheduled to attend the United Nations Climate Change Conference in Paris this week, but security concerns caused his plans to change.
“Ask David what time it is and he’ll tell you how to build a watch,” Susan Polack said, “but in terms you can understand.”
Joy got a Ph.D. in geology from Princeton in 1984 — she and David met there as two of the few early risers — and was appointed as a postdoctoral research scientist at the University of California Los Angeles while he had an appointment at Cal Tech studying the atmosphere of Venus. At UCLA, she conducted experiments subjecting rocks from the Canary Islands to high pressures and temperatures, testing the reactions of the rocks at conditions like those experienced beneath volcanoes.
She never thought of working at the Jet Propulsion Lab. “They study space,” she said. “I never even checked about a job until a friend of ours said, hey, there’s an opening for a post-doc looking at volcanoes using NASA infrared technology.” She began looking at lava on Earth and that led her to studying lava on Mars using satellite photos. By measuring the shadows, Joy tried to figure out the height of the lava flows on Mars. It helped that she spent her early years as a math major. “The Mars Pathfinder mission came along in the ’80s,” she said, “and they needed somebody who understood the chemistry of rocks.”
From that beginning, Joy was lead scientist on the twin Mars rovers, Spirit and Opportunity, and then moved to Curiosity, a 1-ton rover that has covered 7.3 miles on Mars in three years. It drills into rocks and scoops up soil for analysis and sends the data to Earth. Scientists are looking for microbial life. “We hit the jackpot not too long after landing,” Joy said, “measuring some lake bed rocks with clays in them. We identified minerals, something we’d never done before on Mars with an X-ray spectrometer.”
Curiosity’s instruments detected evidence of water: rocks with 30 percent clay minerals that can only form in its presence. Joy said the rover found rounded pebbles in a former stream bed and lake sediments where water from rivers formed delta deposits. She said the age of the rock is about 4.2 billion years, about the estimated age of Earth. “Mars is frozen in time,” she said. “We want to learn more about ancient Mars, which might be like ancient Earth.”
The Mars rover is working its way along a giant crater deeper than the Grand Canyon, Joy said. There are 3 miles of exposed rock in layers. “We can detect mineral differences in layers: sulfates, clays, hematite, an iron-rich layer. We know there should be different types of environments locked in the rock record and by drilling and analyzing the samples we can try to distinguish what it was like back then. Billions of years are exposed.”
David said he and Joy often ask “Can you top this?” on their way home from work. He said Joy’s team is five times larger than his: 500 scientists around the world. “Driving a rover around Mars is about a thousand times harder than having an instrument in orbit look down,” he said.
There’s plenty that can go wrong in orbit. The original Hubble Space Telescope sent back pictures that were out of focus. “As astronomers,” David said, “we knew exactly what was wrong with the first images. We have a fine sensitivity for bad optics.”
Hubble was scheduled to get a new camera because scientists didn’t think it would withstand the harsh environment of space for more than five years. David had made the spectral filters for the original camera and helped find a way to correct the lens flaw the width of a human hair. He introduced an opposite flaw, a conjugate error, in another lens. “We stopped what we were doing,” he said, “tore the camera apart and implemented the fix for the Hubble. It would have had the same problem.” The new camera was installed by astronauts on Dec. 7, 1993, and stayed in the telescope for 15 years. “By sheer dumb luck,” he said, “the astronauts put it in within 2 percent of perfect.” The repaired Hubble’s first image of a star was in focus. There’s a YouTube video of David and NASA scientists seeing it for the first time.