A Pioneering View of Earth
Not many geophysicists have beaten three-time America's Cup winner Dennis Conner in a sailing race, but JPL's senior research scientist Dr. Anne Kahle has. The cover of a 1982 issue of Yachting magazine shows her at the helm of her boat Red Shift, named for Einstein's law describing one effect of gravity on light.
Light and radiance are what the instrument she helped create for NASA's Terra satellite measures. Launched in 1998, the Advanced Spaceborne Thermal Emission and Reflection Radiometer, or Aster, views Earth with 14 spectral bands, from the visible to the thermal infrared. It provides high-resolution images of Earth's surface and detailed maps of surface temperature.
Kahle has helped skipper the Aster along since the very beginning and heads Aster's U.S. Science Team. Its dozen members decide what the instrument will observe and make sure it's providing accurate data. They also use the data in their own research. For Kahle, that means using Aster to study lava fields in Hawaii.
From Alaska Homesteader to Pioneer in Remote Sensing
Born in Auburn, Wash., Kahle moved with her family to Alaska when she was 6. Her family homesteaded 160 acres on the Kenai Peninsula, where her father built his own log house.
There were no schools and no roads. "For high school, my brother and I went to the town of Kenai," says Kahle. "They let me graduate when I was 16. My parents looked around-there were ten families in our area-and said that there are no eligible bachelors here, you need to go to college to meet some."
Kahle did find love at the University of Alaska. She started out studying agriculture and switched to wildlife management. "Then I was offered a job in the geological institute, and I fell in love with geophysics." She worked with renowned British mathematician and geophysist Sydney Chapman, a pioneer in geomagnetism.
While completing her master's degree, she fell in love again, this time with a fellow Earth scientist, Jim Kahle. After graduation, they married and moved to Nome. "We had four kids in five years," says Kahle, "I call those my barefoot and pregnant years."
When her husband wanted to go to graduate school at UCLA, the family moved to Southern California. Kahle went to work at the Rand Corporation on geomagnetism and climate modeling. "One major factor in climate modeling is the heat balance of Earth's surface," says Kahle, "modelers want to know just how much heat is being exchanged between the surface and the atmosphere. This is a job for remote sensing."
While at Rand, she competed her Ph.D. in meteorology at UCLA. Her husband, an earthquake expert, went to work for the California State Division of Mines and Geology. "My husband is a fault finder," she jokes, "not every wife would be happy describing her husband that way."
After coming to JPL in 1974, Kahle proposed one of the first multi-spectral thermal missions. The Thermal Infrared Multispectral Scanner, called Tims, flew on a NASA aircraft. "It provided a lot of good geology," says Kahle, "so we decided to go to space with it."
NASA accepted Kahle's proposal for what would become the Aster instrument in 1988, and the Japanese, who were particularly interested in the instrument's potential in mineral exploration, decided to build it. They asked Kahle to lead the U.S. Science Team.
"I'm not an engineer," says Kahle, "I couldn't build an instrument if my life depended on it. But I got to say I want it to do this and to do that and make decisions about the inevitable trade-offs."
Moshe Pniel, now scatterometer projects manager at JPL, was the Aster project manager during launch and the mission's first two years of operations. "Anne is a very warm person and has a very down-to-Earth view of life," he says. "While she can be very aggressive in pushing for the science she believes in, she has a clear balance of work, family and other interests. It is going to be the end of an era when she retires. She is a founding father of thermal infrared remote sensing. "
Flying for three years now, Aster is fulfilling Kahle's expectations. It is being used for studies of geology, natural hazards, urban growth, wetlands and land use. "With its high spatial resolution and multi-spectral thermal data, Aster gives us a zoom lens, something we've never had before," says Kahle. "Since different materials radiate heat in different wave lengths, Aster reveals a lot of geological information about Earth's surface. Plus we have the thermal infrared, which shows us the heat balance at the surface. It helps calibrate our climate models."
Though Aster produces beautiful and striking images, Kahle won't chose a favorite. "They're all nice," she says. However, she will pick out some of Aster's recent accomplishments. "One of Aster's missions is to monitor Earth's glaciers, and it has shown us some dramatic changes in the past few years," says Kahle. "It also provides digital elevation models of glaciers, measurements of their height, that we didn't have before. In addition, we're monitoring all Earth's active volcanoes. Aster's thermal bands were able to identify hot spots in a volcano in Chile that was previously thought to be dormant."
After 28 years at JPL, Kahle still enjoys her job. "I like the team, the people, the data, and the travel." But, as always, she has other interests, including three grandchildren, two in college and one 8 years old. Sailing has given away to another passion." I'm an avid bird watcher," she says. "I've been bird-watching in all 50 states and all over the world." Her lifetime bird list, kept "compulsively," includes 4,260 different species. Now that her husband is retired, he shares the travel, fishing while Kahle adds species to her list.
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