2008 Annual Report - NASA Airborne Science Program

NASA
G-3
During FY 2008, the DFRC
Gulfstream III (C-20) aircraft
flew 43 sorties for 146
flight hours supporting the
integration and testing of
System 1 of the Unmanned Aerial Vehicle
Synthetic Aperture Radar (UAVSAR).
The UAVSAR is a pod-mounted L-band
polarimetric imaging radar, designed and built
by the Jet Propulsion Laboratory to perform
repeat-pass interferometric measurements.
An electronically steerable antenna is used to
compensate for aircraft motion and reduce
phase errors. Within the aircraft system, a
Platform Precision Autopilot (PPA) controls
the flight path of the aircraft to within a 10-
meter variation from the programmed flight
path. These two systems work together to
allow very precise repeat pass interferometric
measurements. A second, identical system
has been developed and will be tested and
used for science missions in FY 2009.
Testing of the PPA was completed in
January of 2008, and subsequent testing of
the UAVSAR began. Flights were initially
conducted over corner reflector arrays at
the Rosamond Dry Lake in the Mohave
Desert of California. Additional flight lines
were collected over the Hayward and San
Andreas Faults, the Salton Sea, Long Valley,
Kings Canyon, and Mt. St. Helens. The data
demonstrated the instrument to be one of
the finest of its kind in the world. The subset
of an image below shows the caldera of Mt.
St. Helens with two merging glacier lobes
(center left). The UAVSAR is expected to
produce imagery supporting breakthrough
science in the areas of surface deformation,
volcanoes, ice movement, and vegetation
structure.
69