The NASA-ISRO SAR Mission: An International Partnership for Science and Society (Invited Presentation)

The National Aeronautics and Space Administration (NASA) has partnered with the Indian Space Research Organisation (ISRO) to launch a dual frequency (L- and S-band) SAR to observe dynamic changes on Earth. The NASA-ISRO Synthetic Aperture Radar (NISAR) mission will determine Earth change in three science disciplines (solid earth, ecosystems, and cryospheric sciences) using SAR interferometry and polarimetry, and support other science and applications areas. The NISAR instrument utilizes an array-fed reflector (12-m diameter) SAR configuration to enable ~240 km imaging swath at full radar resolution; the L-band SAR (provided by NASA) and the S-band SAR (provided by ISRO) share the reflector.

To characterize changes on Earth, often occurring at unpredictable times and locations, the science plan calls for a highly repetitive global observation strategy, covering all land and ice-covered surfaces on both ascending and descending parts of the orbit every 12 days. Science data at various product levels (raw, imagery, polarimetric, and interferometric products) will be provided through the NASA and ISRO data centers, according to an open data policy. These mission characteristics – ubiquitous open data acquired with a regular and reliable sampling strategy – create excellent opportunities for improving disaster monitoring and rapid response applications. Since disasters are extreme cases of the unpredictable changes NISAR is designed to measure, the consistency of the data set from before to after a disaster will facilitate change detection: The time series prior to an event can be compared to new data acquired after an event, with the changes evident. With NISAR's long wavelength radars, small changes in the surface due to natural variability will be less prominent, allowing ground processing systems to develop automated, robust detection algorithms. NISAR is being designed with the capability to prioritize data takes so they can be rapidly transmitted to the ground after acquisition. This capability is specifically for urgent response requests. A rapid response data system is envisioned as the means for delivering rapid response products to the community. In addition to response products for earthquakes and volcanic eruptions, there are a number of products that could be developed for weather-related disasters, including flood inundation maps, hurricane/typhoon inundation and damage assessments, rain-induced landslides, and high-resolution ocean winds of approaching storms.