Indo-US advanced imaging satellite NISAR completes orbital tests, declared operational

Over five months after it was launched from India's eastern seaboard, the NASA-ISRO Synthetic Aperture Radar (NISAR) satellite has entered its ‘science phase’, implying that it is now fully operational and beaming usable scientific data to Earth.

The satellite co-developed by the US’ National Aeronautics and Space Administration (NASA) was launched onboard Indian Space Research Organisation’s (ISRO) GSLV-F16 from the Satish Dhawan Space Centre on July 30 and has been undergoing tests and calibrations since.

“On the 100th day of NISAR in-orbit, the S-SAR images are released to the public by the Chairman, ISRO, and Secretary, Department of Space. With this, the commencement of the science phase has also been announced,” ISRO said on Friday.

After the successful launch of NISAR, the 12-meter diameter antenna reflector was successfully deployed, which plays a key role for both ISRO’s S-Band and NASA’s L-Band Synthetic Aperture Radar (SAR) Payload. The antenna was launched in a stowed condition on a 9-meter-long boom, which was tucked close to the satellite. The antenna and the boom were developed by NASA.

The unfolding of the joints of the boom commenced on August 9, and was carried out over a period of five days. The reflector assembly mounted on the end of the boom was deployed successfully on August 15, and the performance of the antenna systems is satisfactory, ISRO said.

The entire operations were carried out from ISRO Telemetry Tracking and Command Network (ISTRAC), with the support from NASA’s Jet Propulsion Laboratory.

Since the first acquisition of data on August 18, NISAR S-Band SAR is regularly imaging over Indian landmass and global calibration-validation sites in various payload operating configurations.

Reference targets such as corner reflectors were deployed around Ahmedabad, Gujarat and a few more locations in India for calibration of the images. Data acquired over the Amazon rainforests were also used for calibration of spacecraft pointing and images.

Based on this, payload data acquisition parameters were fine-tuned resulting in high quality images. Initial analysis by scientists and engineers revealed the potential of S-Band SAR data for various targeted science and application areas like agriculture, forestry, geo-sciences, hydrology, polar/Himalayan ice/snow and oceanic studies.

NISAR’s first image captured the fertile Godavari river delta in Andhra Pradesh. Various vegetation classes like mangroves, agriculture, arecanut plantations, acquaculture fields, etc are clearly seen in the image. “The image highlights NISAR’s S-Band SAR ability to map river deltas and agricultural landscapes with precision,” ISRO said.

The 2,392-kg satellite is the first space platform to observe the earth with a dual frequency and detect changes in the planet’s surface down to “fractions of an inch”. It is focused on Earth observation for scientific purposes, particularly for understanding changes in ecosystems, ice mass, vegetation and natural hazards.