AIRSAR-NG, a reconfigurable, multi-frequency (L, P, Ka-band) synthetic aperture radar (SAR), is specifically designed to acquire airborne repeat track SAR data for differential interferometric measurements. Differential interferometry can provide key deformation measurements, and is important for studies of landslides, flooding, fire burn areas, earthquakes, volcanoes and other dynamically changing phenomena.
Using precision real-time GPS and a sensor controlled flight management system, the system can fly predefined paths with great precision (to be within a 10 m diameter tube about the desired flight track).
The radar is designed to be portable between different aircraft platforms, but will initially be demonstrated on a NASA Gulfstream IV. The program began as an Instrument Incubator Project (FlexDSAR IIP) funded by NASA Earth Science Technology Office (ESTO).
The L-band radar is fully polarimetric, with a range bandwidth of 80 MHz (2m range resolution), and a range swath greater than 16 km. The L-band antenna may be electronically steered along track utilizing a new digital beam-steering algorithm to assure that the antenna beam can be directed independently, regardless of speed and wind direction. Other features supported by the antenna include elevation monopulse and pulse-to-pulse re-steering capabilities that will enable some novel modes of operation. The system will nominally operate at 41,000 ft (13800 m).
The P-band RF hardware is inherited from UAVSAR and the AirMOSS EVS-1 mission to observe sub-canopy and subsurface root zone soil moisture. Most of the P-band (420-440 MHz) RF Hardware will translate directly from UAVSAR to AIRSAR-NG with some modifications to signal condition the RF signals going in and out of the new digital system.
The Ka-band single-pass interferometric SAR capability (GLISTIN-A) was added through NASA's Advanced Instrument Technology Transition program (AITT). The horizontally polarized GLISTIN-A (35.62-35.70 GHz) instrument generates high-precision, high resolution, large-swath digital surface models for ice surface topography mapping. Similar to the P-band RF Hardware, the Ka-band GLISTIN-A hardware will be largely inherited to AIRSAR-NG with some modifications to adapt to the new digital system.
