Context: NISAR satellite jointly developed by the Indian Space Research Organisation (ISRO) and the National Aeronautics and Space Administration (NASA) will map the most earthquake-prone regions in the Himalayas. The data generated can potentially give an advance warning of land subsidence, as recently observed in Joshimath, Uttarakhand, and point places that are at greatest risk from earthquakes.
- NISAR (NASA-ISRO Synthetic Aperture Radar) is an Earth-observation satellite expected to be launched in January 2024 from Satish Dhawan Space Centre in Andhra Pradesh into a sun-synchronous orbit.
- The 2,800 kilograms satellite consists of both L-band and S-band synthetic aperture radar (SAR) instruments, which makes it a dual-frequencyimaging radar satellite. SAR is capable of penetrating clouds and can collect data day and night regardless of the weather conditions.
- L-band SAR operates at a frequency of around 1 to 2 GHz. The lower frequency (higher wavelength) of L-band SAR allows it to penetrate through vegetation and soil, making it useful for monitoring changes in forest cover, soil moisture etc.
- S-band SAR operates at a frequency of around 2 to 4 GHz. S-band SAR has a higher resolution than L-band SAR and is typically used for applications where higher detail is required, such as monitoring changes in urban areas or coastal zones.
- The spacecraft will orbit the Earth in a sun-synchronous orbit of 747 Km with a 12-day repeat cycle.
- The NISAR satellite with two frequency bands: L-band and S-band will image the seismically active Himalayan region that will create a “deformation map” every 12 days and provide high-resolution, all-weather data.
- While satellite imagery to study deformation in land is already employed in India, the frequency at which observations are taken and the clarity of the images is critical.
- With a frequency of 12 days and the ability to be able to provide images even under cloudy conditions, NISAR would be a valuable tool to study deformation patterns, such as in Joshimath.
- Study Earth’s dynamic land and ice surfaces in greater detail and observe subtle changes in Earth’s surfaces. E.g., Track flow rates of glaciers and ice sheets, landslide-prone areas and changes in the coastline etc.
- Spot warning signs of natural disasters, such as volcanic eruptions, earthquakes and landslides.
- Measure groundwater levels, agricultural mapping, natural resource mapping and monitor Earth’s forest and agricultural regions to improve understanding of carbon exchange.