India-US advanced Earth observation satellite NISAR completes tests, ready to beam scientific data

The NASA-ISRO Synthetic Aperture Radar (NISAR) Earth-observing radar satellite mission, has completed its tests in orbit and is now on track to start beaming scientific data back to ground stations.

After launching on July 30, the NISAR, a joint effort between the US National Aeronautics and Space Administration (NASA) and the Indian Space Research Organisation (ISRO), is on schedule to start science operations this fall, NASA posted on its website on Friday.

Following the deployment of its 39-foot-wide radar antenna reflector on August 15, engineers powered on the satellite’s L-band and S-band synthetic aperture radar (SAR) systems. Together, these systems will track movement of Earth’s ice and land surfaces in unprecedented detail.

“In addition, the spacecraft, including the radar payload, has passed all preliminary checks performed by NASA and ISRO mission teams to ensure they are operating normally. The mission began raising the satellite to its operational orbit at 747 kilometres mean altitude on August 26,” the post said.

“The mission team anticipates having science-quality radar images in the coming weeks. Full science operations have been scheduled to begin about 90 days after launch,” it added.

Launched by ISRO’s GSLV F-16 rocket from Sriharikota on the south-eastern coast, the NISAR mission is the first to carry two SAR systems. The L-band radar transmits and receives signals at a 10-inch wavelength, enabling it to penetrate forest canopies and measure soil moisture, forest biomass and the motion of land and ice surfaces.

The S-band radar, which uses a 4-inch wavelength, is more sensitive to smaller vegetation and ideal for observing certain types of agriculture, grassland ecosystems, and moisture in snow. Both systems can collect data through clouds and precipitation, day and night.

The satellite will monitor most of Earth’s land and ice surfaces twice every 12 days, tracking changes in the planet’s forests, frozen surfaces, major infrastructure, and crust with sub-inch precision. The lattermost is a key measurement in understanding how the land surface moves before, during, and after earthquakes, volcanic eruptions, and landslides, NASA said.

ISRO’s Space Applications Centre provided the mission’s S-band SAR. The UR Rao Satellite Centre provided the spacecraft bus, that is, the satellite platform on which the sensors are mounted. After launch, key operations, including boom and radar antenna reflector deployment, are being executed and monitored by ISRO’s Telemetry, Tracking and Command Network via a global system of ground stations.

NASA’s Jet Propulsion Laboratory (JPL) in Southern California was responsible for the L-band SAR, reflector, boom, high-rate communication subsystem for science data, solid-state data recorder, and payload data subsystem. NISAR’s L-band data is received by NASA’s Near Space Network at the Goddard Space Flight Center in Maryland.