Isro’s GSLV-F17 successfully places EOS-05 Earth observation satellite in geosynchronous orbit
ISRO's GSLV-F17 rocket successfully placed the EOS-05 Earth observation satellite into its intended orbit, marking a step toward India's own geosynchronous Earth-imaging capability.
EOS-05 (GISAT-1A) is fitted with multi-spectral and hyperspectral imaging payloads intended to support near-continuous monitoring of a large area of Earth's surface.
The mission follows an earlier, unsuccessful attempt to place a similar satellite (GISAT-1/EOS-03) in orbit in 2021.
Once operational, the satellite is expected to support weather tracking, disaster management, and agricultural monitoring applications.
Remote Sensing: Multi-Spectral and Hyperspectral Imaging
Remote sensing satellites gather information about Earth's surface by recording electromagnetic radiation reflected or emitted from the ground, without physical contact. Multi-spectral sensors capture data in a limited number of broad wavelength bands (e.g., visible, near-infrared), useful for distinguishing land cover types. Hyperspectral sensors capture data across hundreds of narrow, contiguous spectral bands, allowing much finer discrimination of materials, crop health, mineral composition, and water quality than multi-spectral imaging permits.
Key Details
- Multi-spectral imaging: typically a handful of broad bands (e.g., red, green, blue, near-infrared).
- Hyperspectral imaging: hundreds of narrow, continuous bands, enabling spectral-signature-based identification of specific materials.
- Applications of hyperspectral data include precision agriculture, mineral exploration, environmental monitoring, and defence surveillance.
- EOS-05 is designed to carry advanced imaging across visible, infrared, multi-spectral, and hyperspectral bands.
EOS-05's imaging suite spans both multi-spectral and hyperspectral bands, illustrating how a single Earth observation platform can serve multiple end uses, from weather tracking to agricultural assessment, using different parts of the imaging spectrum.
Geosynchronous Earth Observation: Why Orbit Choice Matters
Most Indian remote-sensing satellites (the IRS/EOS series prior to this program) operate in Sun-synchronous polar orbits at a few hundred kilometres altitude, passing over any given location only once or a few times a day. A geosynchronous imaging satellite instead sits near geosynchronous altitude (about 35,786 km) and can observe the same broad region continuously or at very short intervals, useful for time-critical applications like tracking a developing cyclone or a spreading fire, at the cost of coarser spatial resolution than a low-orbit satellite.
Key Details
- Geosynchronous/geostationary altitude: approximately 35,786 km above the equator.
- Sun-synchronous polar orbit satellites (India's older IRS/Cartosat/EOS missions) typically orbit at 500–900 km, revisiting a location once every day or few days.
- A geosynchronous imaging satellite trades spatial resolution for temporal frequency, enabling repeated imaging of the same region at short intervals.
- India's first attempt at such a satellite, GISAT-1/EOS-03, was lost in an August 2021 GSLV-F10 launch failure caused by a cryogenic-stage valve leak.
EOS-05/GISAT-1A succeeds where the 2021 GISAT-1/EOS-03 mission failed, giving India its first operational geosynchronous imaging satellite and a new capability layer alongside its existing constellation of polar-orbiting Earth observation satellites.
Disaster Management and Satellite-Based Early Warning
Satellite Earth observation is a recognised input to India's institutional disaster management framework under the Disaster Management Act, 2005, which established the National Disaster Management Authority (NDMA). Near-real-time imagery from satellites supports flood mapping, cyclone tracking, and post-disaster damage assessment, feeding into NDMA and state disaster management authorities' response planning.
Key Details
- The Disaster Management Act, 2005 established the NDMA, chaired by the Prime Minister, as India's apex disaster management body.
- ISRO's Disaster Management Support Programme uses satellite data (optical, hyperspectral, and radar) for hazard mapping and monitoring.
- Rapid-revisit imaging, such as that promised by a geosynchronous satellite, is particularly valuable for monitoring fast-evolving hazards.
ISRO has positioned EOS-05 as a tool for improving disaster management support, aligning satellite capability development with the institutional disaster response architecture built under the 2005 Act.
- Satellite: EOS-05, also designated GISAT-1A.
- Launch vehicle: GSLV-F17, from Satish Dhawan Space Centre, Sriharikota.
- Time to orbit insertion: approximately 18 minutes after lift-off.
- Reference geosynchronous altitude: approximately 35,786 km.
- Predecessor mission GISAT-1/EOS-03 was lost in the GSLV-F10 launch failure of August 2021.
- NDMA was established under the Disaster Management Act, 2005.