ISRO Develops a radar for the Joint Earth Observation Satellite Mission with NASA

ISRO has completed the construction of a Synthetic Aperture Radar (SAR) capable of generating extremely high resolution images for a joint Earth observation satellite mission with the US Space Agency National Aeronautics and Space Administration (NASA). NASA-ISRO SAR (NISAR) is a collaborative partnership between the dual-frequency L and S-band SAR for Earth Observation.

“NISAR will be the first satellite mission to use two separate radar frequencies (L-band and S-band) to monitor shifts in the surface of our planet less than a centimeter wide,” according to NASA. NASA and Bengaluru-based Indian Space Research Organization (ISRO) signed an agreement on 30 September 2014 to collaborate and launch NISAR.

The mission is to launch at the beginning of 2022 from the Sriharikota ISRO spaceport in Andhra Pradesh’s Nellore district, about 100 km north of Chennai. NASA provides an L-band SAR mission, a high-speed communication subsystem for science data, GPS receivers, a solid-state recorder, and a payload data subsystem.

ISRO provides mission launch services for the spacecraft bus, the S-band radar, the launch vehicle and related launch services, the purpose of which is to make global measurements of the causes and effects of land surface changes using advanced radar imaging.

On 4 March, the S-band SAR payload of the NISAR satellite mission was flagged off by the Secretary of the Department of Space and ISRO Chairman K Sivan via virtual mode.

The payload was shipped from ISRO’s Ahmedabad-based Space Applications Center (SAC) to NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, USA, for integration with the latter’s L-band SAR payload, ISRO said.

“NISAR will provide a means of disconnecting highly spatial and temporally dynamic systems, ranging from ecosystem disruptions to ice sheet collapses and natural hazards, including earthquakes, tsunamis, volcanoes and landslides,” ISRO said.

NASA added that the project would calculate Earth’s evolving habitats, complex surfaces, and ice masses, provide information on biomass, natural disasters, rising sea levels, and groundwater, and help a host of other applications.

“NISAR will observe Earth’s land and ice-covered surfaces globally with 12-day regularity on ascending and descending passes, sampling Earth on average every six days for a baseline three-year mission,” NASA said on the mission website.

“This allows the mission to study a broad variety of Earth processes, from the flow of glaciers and ice sheets to the dynamics of earthquakes and volcanoes.” NISAR uses a complex information-processing method known as SAR to achieve extremely high resolution images.

Radar penetrates clouds and darkness, allowing NISAR to collect data day and night in any weather. The width of the data strip collected along the length of the orbit track is greater than 150 miles (240 km), which enables the image of the entire Earth in 12 days, it has been claimed.

In multiple orbits, radar images would enable users to track changes in cropland and hazard sites, as well as to monitor ongoing crises, such as volcanic eruptions. The images will be precise enough to display local changes and broad enough to quantify regional trends.

As the project continues for years, the data will make it possible to better understand the causes and effects of land change, increase our capacity to handle resources and plan for and cope with global change, according to NASA.

“NASA needs a minimum of three years of global science operations with L-band radar, and ISRO requires five years of S-band radar operations across identified target areas in India and the Southern Ocean,” it said.

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