Surface changes

NASA is evaluating a compact L-Band synthetic aperture radar that can detect and measure small changes in the Earth’s surface.

The radar will allow scientists to examine areas of scientific interest, such as volcanoes, earthquake faults, landslides and glaciers.

NASA’s Dryden Flight Research Center and the Jet Propulsion Laboratory (JPL) joined forces to develop the so-called Unmanned Aerial Vehicle Synthetic Aperture Radar (UAVSAR).

During validation flights, a modified NASA Gulfstream III aircraft will carry the radar in a custom-built pod about 10ft (3.048m) in length under the aircraft’s fuselage. The pod also contains a two-terabyte recorder to store the large amounts of data generated by the radar.

The Gulfstream III will make two passes across sections of the Earth’s surface. Data captured by the the synthetic aperture radar will then be used to highlight surface displacement with a sensitivity equal to a fractional part of the radar wavelength.

The radar’s electronically steered antenna compensates for aircraft attitude changes as the radar makes repeated passes over areas of interest.

The UAVSAR underbelly pod is in clear view as NASA’s Gulfstream-II research aircraft banks away over Edwards AFB during aerodynamic clearance flights

The instrument itself has its own navigation system consisting of a inertial navigation unit and a differential GPS developed at JPL that provides the aircraft’s location to an accuracy of less than three feet.

The radar is currently undergoing a one-year development and test period to improve robustness and validate its ability to meet its objectives. The UAVSAR will be extensively tested through 2008, after which it will become a so-called community science tool for NASA.