ISRO-NASA Radar to Map Earth's Changing Landscapes in Unprecedented Detail
- NISAR, a joint ISRO-NASA mission, is scheduled to launch in 2025.
- It will use L-band and S-band radar to observe Earth's land and ice surfaces.
- Data will be collected every 12 days, allowing scientists to track changes in forests, wetlands, and glaciers.
- The mission aims to improve understanding of carbon cycles, natural hazards, and climate impacts.
- NISAR's high-resolution imagery will be freely available to global researchers.
The Indian Space Research Organisation (ISRO) and NASA are finalising preparations for the NISAR satellite, a joint mission that promises to transform how scientists observe Earth's shifting surface. Slated for launch in 2025, the satellite will use dual-frequency radar to scan nearly all of the planet's land and ice sheets every 12 days.
NISAR stands for NASA-ISRO Synthetic Aperture Radar. It is the first space mission of its kind to combine two different radar frequencies — L-band and S-band — on a single satellite platform. This combination allows it to see through clouds and darkness, capturing images day and night.
Radar eyes on forests and ice
The satellite's primary goal is to measure changes in Earth's ecosystems, including forests, wetlands, and agricultural lands. It will track deforestation, regrowth, and flooding with far greater precision than current satellites.
In polar regions, NISAR will monitor the movement of ice sheets, glaciers, and sea ice. Scientists expect the data to improve projections of sea level rise. The radar can detect shifts in the ground as small as a few centimetres.
Researchers in India will particularly benefit from the S-band radar, which is sensitive to soil moisture and vegetation structure. This will aid in assessing crop health and water availability across the subcontinent.
Monitoring hazards from space
NISAR will also serve as a tool for disaster monitoring. Earthquakes, landslides, volcanic activity, and subsidence are all within its observational scope. By comparing radar images taken over time, scientists can spot ground deformation before and after such events.
For instance, the satellite can map the extent of floodwaters even during heavy cloud cover — something optical satellites cannot do. This makes it a critical asset for emergency response agencies in India and the United States.
The mission's data policy is open. All imagery and derived products will be made freely available to researchers and the public within days of collection.
A decade of observation
NISAR is designed to operate for at least three years, with a goal of ten. The sheer volume of data — roughly 80 terabytes per day — will be processed using ground stations in India and the US.
ISRO is building the spacecraft bus and the S-band radar. NASA is supplying the L-band radar, the high-gain antenna, and the data recorder. The satellite is being assembled at ISRO's facility in Bengaluru.
The partnership marks one of the most ambitious Earth science collaborations between the two space agencies. Previous joint efforts include the Chandrayaan and Mars Orbiter missions, but NISAR is focused entirely on Earth.
The launch vehicle will be India's Geosynchronous Satellite Launch Vehicle (GSLV) from the Satish Dhawan Space Centre in Sriharikota. The exact launch date is yet to be announced, but officials have indicated it will be in the first half of 2025.
Once in orbit, NISAR will join a constellation of Earth-observing satellites. Its unique capability to map the planet's changing surface every 12 days will fill a critical gap in monitoring environmental change.