Scientists flying high above the South Pole have made the first high-altitude radar measurements of the snow and ice beneath the pole's Scott-Amundsen Research Station.
A radar beam transmitted from a four-engine NASA jetliner flying at 39,000 feet penetrated nearly 3 kilometers of ice to the bedrock, then returned to the plane. The radar echoes were converted into a shadowy profile of the layered ice and the bedrock.
The feat was part of the second season of Operation IceBridge. It's a six-year NASA mission to measure changes in Antarctic sea and land ice, led by Michael Studinger of the Goddard Earth Sciences and Technology Center at the University of Maryland, Baltimore County.
"It is a remarkable accomplishment and a milestone in radar technology that we are able to do this," Studinger said by phone Monday from the mission's base in Punta Arenas, Chile. "It's an important data set for the international community. Little is known about the rock beneath the ice sheet and the ice thickness at the pole."
While polar-orbiting satellites can provide views of most of Antarctica 365 days a year, they cannot reach the pole itself with down-looking laser altimeter measurements and cannot carry ice-penetrating radar equipment. "The measurements we have taken there from 39,000 feet we can't do from space," Studinger said. "We don't have the technology at the moment to do this."
This year's IceBridge flights from southern Chile to Antarctica began Oct. 26. The plane is equipped with ice-penetrating radar, laser altimeters and five other instruments. When the weather permits, the aircraft and its crew of 24 make 11- and 12-hour flights over sea ice on both sides of the Antarctic Peninsula, and the glaciers and snowcover on the continent itself.
With repeated flights over the same trajectories, precisely guided by global-positioning satellites and inertial guidance systems, the scientists hope to gather a seven-year record of changes in the height and thickness of the ice and snow below.
"This is important because we really need to understand how ice sheets and glaciers respond to changing climate," Studinger said.
The aircraft data will fill the gap between measurements collected by NASA's ICESat satellite from 2003 to 2009, and more data anticipated from ICESat 2, scheduled to launch in 2015.
"We wanted to avoid an 'Oh, my God' moment when we come back in six years with ICESat 2. We wanted continuity," said Seelye Martin, an IceBridge research scientist from the University of Washington, Seattle.
Data from the first ICESat satellite has revealed "very dramatic" changes in the height of the Crane Glacier on the Antarctic Peninsula, said UMBC research scientist Chris Shuman. The losses averaged 15 inches a day, with a drop of 557 feet between 2002 and 2009.
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