'Earth's Imagery Down To The Centimetre': Why NISAR Is Like No Mission Before

The US-India NASA-ISRO Synthetic Aperture Radar or NISAR mission will observe the Earth down to the centimetre, monitoring its land and ice surfaces, NASA's Jet Propulsion Laboratory Scientist Paul Rosen said.

The agreement was inked on 2014 to track changes in wetlands to ice sheets to infrastructure damaged by natural disasters through the dual band radar satellite, which will launch from ISRO's Satish Dhawan Space Centre in Sriharikota in March.

How NISAR Will Work

The drum-shaped radar antenna reflector, measuring about 39 feet (12 meters) across, is among NASA's contributions to the joint mission. It has been specially designed to help focus the transmitted and received microwave signals to and from the surface of the Earth.

NISAR will feature an L-band system with a 10-inch (25-centimeter) wavelength and an S-band system with a 4-inch (10-centimeter) wavelength. Microwaves can reflect or penetrate an object depending on their wavelength. Shorter wavelengths are more sensitive to smaller objects such as leaves and rough surfaces, whereas longer wavelengths are more reactive with larger structures like boulders and tree trunks.

This will enable NISAR to scan roughly all of the Earth's land and ice surfaces twice every 12 days to collect scientific data.

A NASA-ISRO Collaboraton

Space Applications Centre Ahmedabad, ISRO's lead center for payload development, is providing the mission's S-band SAR instrument and is responsible for its calibration, data processing, and development of science algorithms to address the scientific goals of the mission. U R Rao Satellite Centre in Bengaluru, which leads the ISRO components of the mission, is providing the spacecraft bus. The launch vehicle is from ISRO's Vikram Sarabhai Space Centre, launch services are through ISRO's Satish Dhawan Space Centre, and satellite mission operations are by ISRO Telemetry Tracking and Command Network. National Remote Sensing Centre in Hyderabad is primarily responsible for S-band data reception, operational products generation, and dissemination.

NASA is providing the mission's L-band Synthetic Aperture Radar (SAR), radar reflector antenna, the deployable boom, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder and payload data subsystem.

What Will Be The Outcome?

Key observations from NISAR will help researchers worldwide get unprecedented insights into the changes in the Earth's surface, including the ice sheets, sea ice and glaciers. It will also monitor changes in the forest and wetland ecosystems, besides tracking the movement and deformation of the crust like landslides, earthquakes as well as volcanic activities.

"With NISAR, we'll measure that change roughly every week, with each pixel capturing an area about half the size of a tennis court. Taking imagery of nearly all Earth's land and ice surfaces this frequently and at such a small scale - down to the centimeter - will help us put the pieces together into one coherent picture to create a story about the planet as a living system," Mr Rosen said.

The coverage from NISAR will help shape disaster response, producing data to assist in mitigating and assessing damage, with observations before and after catastrophic events available in short time frames.

How Will The Data Be Made Accessible?

Mr Rosen said that NASA decided the data would be processed and stored in the cloud, where it'll be free to access.