Context: The NASA-ISRO Synthetic Aperture Radar (NISAR) satellite was successfully launched on 30th July 2025 from the Satish Dhawan Space Centre at Sriharikota in Andhra Pradesh.
The Geosynchronous Satellite Launch Vehicle (GSLV-F16) successfully lifted and precisely injected the NISAR satellite weighing 2,392 kg into its intended sun-synchronous orbit.
Relevance of the Topic: Prelims: Key facts about NASA-ISRO Synthetic Aperture Radar (NISAR) Mission.
About NISAR:
- NISAR is a Low Earth Orbit (LEO) observatory which will be placed in sun-synchronous orbit at an altitude of 747 km and an orbit inclination of 98.4°.
- It is a joint project between NASA and the Indian Space Research Organization (ISRO) to develop and launch a radar imaging satellite. The satellite will be the first to use dual frequencies.
- Duration: Baseline mission duration of three years.
- Estimated Mission Cost: $1.5 billion.
- The Earth observation satellite is capable of penetrating cloud cover and operating day and night regardless of the weather conditions, expected to revolutionise earth-observing capability. NISAR will observe nearly all the planet’s land and ice surfaces twice every 12 days.
- The 2,800 kilograms satellite consists of both L-band and S-band synthetic aperture radar (SAR) instruments, which makes it a dual-frequency imaging radar satellite.
- 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 resolution is required, such as monitoring changes in urban areas or coastal zones.
Significance:
- NISAR will observe natural processes and changes in earth’s complex ecosystems.
- 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 earthquakes, tsunamis, volcanoes and landslides.
- Measure groundwater levels, agricultural mapping, vegetation biomass, natural resource mapping and monitor Earth’s forest and agricultural regions to improve understanding of carbon exchange.