New Radar Map and Spy Satellites Expose Antarctica

In 1963, six years after the Russians launched Sputnik to begin the era of satellites, the U.S. Department of Defense was busy with the new technology. Satellites orbiting the planet took detailed photographs of the entire world, including Antarctica.

Because those images have recently been declassified, scientists are learning an incredible amount about Antarctica by comparing the photos with the first radar map of the continent, a project scientists at the Geophysical Institute are helping to complete.

Antarctica, a snow-covered land mass three times the size of Alaska, was a last frontier of radar mapping until last fall. From September 26 to October 14, 1997, a Canadian satellite orbiting at 500 miles above Earth sent down radar pulses, received the bounced signals from the surface of Antarctica, then transmitted the information to several sites in Canada and the U.S., including the big blue dish on top of the Geophysical Institute at the University of Alaska Fairbanks.

Led by Nettie Labelle-Hamer, coordinator of the Antarctica Mapping Mission, scientists at the Alaska Synthetic Aperture Radar Facility have been compiling the data from the satellite to give the first-ever clear look at the entire continent of Antarctica. Though older maps had been made with conventional radar, those included areas of cloud cover that block parts of the surface. Because synthetic-aperture radar penetrates through clouds, the Antarctic Mapping Mission produced what researchers hoped would be a good look at the polar ice cap for future comparison. Now, with the availability of satellite photos from the 1960s, researchers are able to see what's happened to Antarctica in the past 30 years.

Ken Jezek, director of the Byrd Polar Research Center at Ohio State University, is one of the scientists retrieving the photos for use in scientific research. "A committee convened by Vice President Gore declassified this data and made it available to the science community," Jezek said from Columbus, Ohio. "We didn't know it existed before that."

The old military photographs cover the entire continent, Jezek said, but in many of the photos the icy surface of Antarctica is hidden by clouds. He said the photos were taken from the satellite with a camera that featured a huge lens and wide-format film. Because the satellites were orbiting several hundred miles above Earth, retrieving the film was an adventure. "The film was jettisoned back to Earth in canisters attached to parachutes," Jezek said. "An aircraft would fly by and snag the parachute on its way down."

With the film now safely on the ground and available for comparison to the images of the Antarctic Mapping Mission, researchers will be able to note the many changes in Antarctica over three decades.

Jezek said for a long time the continent was seen as a static cap of ice, unchanging for thousands of years. However, early looks at the photographs versus the radar images have shown researchers significant changes in the continent, especially where ice sheets flow across the boundary separating rocks beneath glaciers and the ocean.

Changes in Antarctica, especially increased melting, are of concern to anyone who lives near the ocean. Antarctica contains about 70 percent of the world's fresh water supply. When glaciers in Antarctica melt, the ocean responds with a rise in sea level. How much of Antarctica is melting may be a question soon answered by the Antarctic Mapping Mission and satellites from the early 1960s.