NISAR: NASA-ISRO Radar Satellite Mission Explained
Why in the news
India and the US prepared to launch an advanced radar-based Earth observation satellite able to track surface changes in fine detail.
Key facts
- Resolution: 3-10 metres, with vertical accuracy in centimetres.
- Products: annual biomass maps at 1 ha resolution and quarterly cropland maps.
- ISRO’s role: reserved routine S-band operations over India, for soil moisture, crop health, biomass, and less atmospheric distortion.
| Parameter | NISAR detail |
|---|---|
| L-band SAR (NASA) | 1.257 GHz; ground deformation, forests, subsurface |
| S-band SAR (ISRO) | 3.2 GHz; vegetation, moisture, crops, surface texture |
| Orbit | Sun-synchronous polar, 747 km, 98.4 degree inclination |
| Antenna | 12 m mesh reflector |
| Swath | 240 km with SweepSAR |
| Revisit | 12 days |
Objectives
- Track earthquakes, landslides and subsidence, ecosystems and biomass, ice sheets and glaciers, croplands, flooded versus dry land and dam or levee stability.
- Aid climate research, disaster management and resource monitoring.
How it works
- Radar pulses measure return time and phase of the signal.
- Synthetic Aperture Radar combines successive echoes to mimic a large antenna.
- Penetrates clouds, smoke and vegetation; works day or night.
- Horizontal and vertical polarisation helps tell soil, water, crops and snow apart.
Exam angle
- Launch vehicle: GSLV Mk-II from Sriharikota.
- Frequency split: L-band (NASA), S-band (ISRO).
- Revisit: 12 days.