Dr. Robert Crippen expects the Grand Canyon to be delivered to his office any day. Fortunately, it will be a much smaller version of the fifty-two-foot model that he recently helped create for Explorer's Hall at the National Geographic Society's newly remodeled headquarters in Washington, D.C.
Crippen is part research geologist and part geographer. He is a specialist in using remote sensing data, usually images and measurements collected by satellites, to study Earth.
Pictures Tell a Story
For the past two years, he has been working extensively with elevation data gathered by JPL's Shuttle Radar Topography Mission. During its 11-day flight in February 2000, the mission used radar to map more than 80 percent of Earth's landmass. Crippen has created dozens of images (most of which can be viewed on NASA's Planetary Photojournal) with data from the shuttle mission often in combination with other satellite imagery.
Some of his favorites are panoramic and stereoscopic views of Russia's Kamchatka Peninsula.
He generated the images with topographic data from the shuttle radar mission and an enhanced true-color image from the Landsat 7 satellite. "They're not just pretty pictures," Crippen said, "If you look at the Landsat scene, you can see a large lake. But when you put the Landsat scene over the elevation data, you can see that a landslide has created a natural dam and that's why the lake is there. I like them for what they're telling me as well as the artistry."
He also paired shuttle radar mission elevation data with a Landsat image to create a large Patagonia exhibit in Explorer's Hall. The result reveals the complex geology of this remote spot, a place like many on Earth that had been poorly mapped before the shuttle mission. It also showcases the remarkable level of topographic detail the mission was able to gather.
|Dr. Robert Crippen at National Geographic Society
"The engineers have thanked me for making them look good," said the soft-spoken Crippen. "They are good. The Shuttle Radar Topography Mission has been another of those amazing things that JPL has done. People have been trying to map the world for centuries. JPL improved most of that mapping with a mission that lasted just 11 days. Also, the mission established a year 2000 global baseline against which future topographic change can be measured."
Born to Rock
A Seattle native, Crippen grew up in Southern California. His favorite subjects in school were geology, geography and geometry. "My parents should have named me George," he quipped.
His grandparents were rock hounds and owned a rock shop for a time. "My father knows more geography trivia than anybody else I know, including all my geography professors," Crippen said. "A lot of my role in the Shuttle Radar Topography Mission has been terrain visualization, which involves graphic arts. My grandmother and her sisters were excellent artists, and my brother is a graphic artist, so maybe that runs in the family too."
Crippen completed his undergraduate degree with a double major in geology and geography at the University of California Los Angeles and a master's degree in geology and a Ph.D. in Earth science remote sensing at the University of California Santa Barbara. He began working at JPL while he was a graduate student doing research along the San Andreas Fault.
"My first project with JPL included field work in the Mojave Desert, digging with a shovel in 112 degree Fahrenheit heat to find evidence that the Seasat satellite had imaged bedrock beneath a thin cover of sediment. I still do occasional fieldwork, but with all the new data types and desktop computing capabilities, many discoveries can be made while digging through data in the comfort of an air-conditioned office."
Crippen has "a knack for matching wits with satellite data and coming up with unforeseen data," wrote documentarian Nicholas Clapp in his book about the search for the lost city of Ubar. In 1986, Crippen and JPL colleague Ron Blom manipulated Landsat images to reveal an ancient road, a caravan route through the Arabian desert, that helped lead to the rediscovery of the fabled walled city.
A few years later, thinking about what you can and cannot see from a satellite led Crippen to find a way to show the motion of an earthquake fault with satellite imagery for the first time. "I got to thinking that if the ground moved, you might be able to see it in satellite pictures even if the pixels, the digital dots that make up a satellite image, are larger than the movement. We needed the right earthquake to test the idea," he said.
The 1992 Landers quake was such an earthquake. "The Spot satellite provides a 10-meter resolution (each pixel in the image represents an area 10 meters or 33 feet across), and the earthquake created several fault offsets of three to five meters (10 to 16 feet). "By "flickering" an image of the region from before the earthquake with one taken afterwards, you're able to see the effect," said Crippen. The result was the first visual observation of fault motion from space.
Recently, Crippen and Ron Blom devised a new way of processing satellite images that "removes" vegetation to reveal the rocks below. With some sophisticated tweaking, they can, in effect, look through the trees in an image to see what would otherwise be obscured by the forest canopy.
"When I began my career in the 1970s, we had simple crude images to work with. Now we're seeing the Earth in ways we've never seen it before. We always wanted more detail, more spectral bands. Now from space we can see small ground movements and can identify minerals and plants by their distinctive 'colors' in visible and invisible light. A lot of what we dreamed about 20 years ago has come true," said Crippen. "This is the golden age of Earth observation from space."
June 7, 2002