The oddly shaped pod slung beneath NASA's Gulfstream-III research aircraft houses a sophisticated synthetic aperture radar developed by NASA's Jet Propulsion Laboratory. (NASA / Tony Landis) NASA's Gulfstream III environmental research aircraft completed its brief mission to radar image volcanoes in Alaska the first week in August, and now the lengthy work of analyzing the data begins.
During the four-day mission from Aug. 1 through Aug. 4, the G-III flew several flights from its deployment base at Elmendorf Air Force Base near Anchorage, Alaska. The UAVSAR synthetic aperture radar installed in a pod slung under the belly of the G-III imaged volcanoes in the Aleutian Island chain to detect and measure small changes in the Earth's surface of geophysical interest. While the aircraft was en route from its home base at NASA's Dryden Aircraft Operations Facility in Palmdale, Calif., the radar imaged volcanoes in the Cascade Range over California, Oregon and Washington.
"All indications are that data were collected successfully," said scientist Paul Lundgren of NASA's Jet Propulsion Laboratory in Pasadena, Calif., where the specialized radar was developed. "However, to detect changes in activity requires computation of differential interferograms from the new and previously collected data. This processing....typically [takes] several months, so we will know months from now whether there was any volcanic deformation over the past year."
Differential Global Positioning System satellite information is being used in conjunction with the aircraft's precision autopilot to enable the aircraft to repeat flight lines within 15 feet of the originals flown in August 2010. The system depends on corrections received from Iridium and Inmarsat satellites. The radar's electronically steered antenna compensates for aircraft altitude and heading changes as the radar makes repeat passes over areas of interest.