# NISAR (satellite)

The NASA-ISRO Synthetic Aperture Radar (NISAR) mission is a joint project between NASA and ISRO to co-develop and launch a dual-frequency synthetic aperture radar on an Earth observation satellite in 2025. The satellite will be the first radar imaging satellite to use dual frequencies. It will be used for remote sensing, to observe and understand natural processes on Earth. For example, its left-facing instruments will study the Antarctic cryosphere. With a total cost estimated at US$1.5 billion, NISAR is likely to be the world's most expensive Earth-imaging satellite.

## Overview

The NASA-ISRO Synthetic Aperture Radar, or NISAR satellite, will use advanced radar imaging to map the elevation of Earth's land and ice masses four to six times a month at resolutions of 5 to 10 meters. It is designed to observe and measure some of the planet's most complex natural processes, including ecosystem disturbances, ice-sheet collapse, and natural hazards such as earthquakes, tsunamis, volcanoes and landslides.
The mission is a partnership between NASA and ISRO. Under the terms of the agreement, NASA will provide the mission's L-band synthetic aperture radar (SAR), a high-rate telecommunication subsystem for scientific data GPS receivers, a solid-state recorder, and a payload data subsystem. ISRO will provide the satellite bus, an S-band synthetic aperture radar (SAR), the launch vehicle, and associated launch services.
All data from NISAR will be freely available one to two days after observation and within hours in case of emergencies like natural disasters. Data collected from NISAR will reveal information about the evolution and state of Earth's crust, help scientists better understand our planet's natural processes and changing climate, and aid future resource and hazard management.
The satellite will be three-axis stabilized. It will use a 12 m (39 ft) deployable mesh antenna and will operate on both the L- and S- microwave bands. The aperture mesh reflector (antenna) will be supplied by Astro Aerospace.
ISRO's share of the project cost is about ₹788 crore (US$90 million), and NASA's share is about US$1,118 million.

## Launch

The satellite was originally scheduled to be launched from India aboard a GSLV Mark II on 30 March 2024, but it was postponed until further notice due to a needed hardware update. The orbit will be a sun-synchronous, dawn-to-dusk type. The planned mission life is three years. The satellite was fully integrated in January 2024 and was performing its final testing and analysis in preparation for launch. However, in an interview with the Times of India, Chairman of ISRO Sreedhara Panicker Somanath said that though the GSLV for NISAR will be built by March-April, the satellite is still undergoing tests and they were expecting some delay. Tests found that the reflector might face higher-than-expected temperatures when stowed during flight and so it was returned to the manufacturer in California to apply a reflective coating to mitigate the risk of overheating.
On 15 October 2024, after the completion of all checks and tests, NASA's C-130 took off from Wallops Flight Facility in Virginia to embark on the multi-leg, multi-day journey to India. The flight will first stop at March Air Reserve Base to retrieve the spacecraft followed by strategic stops at Hickam Air Force Base, Hawaii; Andersen Air Force Base, Guam; Clark Air Base, Philippines and reach HAL Airport in Bengaluru, India. By late January 2025, the satellite had finished all preliminary checkout in Bengaluru and was shipped to SDSC.
As of December 2024, NISAR is expected to be launched in March 2025.

## Gallery

* NISAR diagram
* NISAR undergoing tests
* NISAR solar array
* NISAR's DGA antenna

## Payload

* L-band (1.25 GHz; 24 cm wavelength) polarimetric SAR, to be produced by NASA.
* S-band (3.20 GHz; 9.3 cm wavelength) polarimetric SAR, to be produced by ISRO.