The GEO Imaging Satellite (GISAT) is India's most powerful GEO earth observation satellite. GEO satellites stay above a fixed landmass thus providing continuous 27x7 surveillance of a geographic area. The area covered by the satellite will include entire Indian territory and surrounding region including Pakistan, western China, and portions of the Indian ocean. There will be two satellites in GISAT family.
GISAT will carry multi-spectral, multi-resolution payload. It will have a mission life of 7 years (limited to fuel reserves required for steering) and a design life of 15 years (limited to radiation shielding). The satellite will have a liftoff mass of 2100kg. The spacecraft is based on a modified version of I-1K bus. GISAT-1 will be launch aboard GSLV MK2 in early 2019.
Imaging sensors on GISAT :
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| Artist's rendition of GISAT in orbit |
GISAT overview
Core objectives of GISAT satellites are :
- Fast revisiting
- Real-time monitoring
- High-resolution multispectral and hyperspectral imaging
Imaging system :
The electro-optical payload of satellite consists of four imaging channel (Multi-spectral VNIR (visible-near infrared) & LWIR (Long-wave infrared), Hyperspectral VNIR & SWIR (short-wave infrared) ) and modified version of the telescope used in CARTOSAT-2A satellite (700 mm Ritchey-Chretien telescope).Imaging sensors on GISAT :
- Multi-spectral VNIR: 50-meter ground resolution
- Multi-spectral LWIR: 1500 meter ground resolution
- Hyperspectral VNIR: <500 meter " "
- Hyperspectral SWIR: <500 meter " "
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| Exploded view |
A major advantage of GISAT over LEO-based CARTOSAT satellites is that it has a very high temporal resolution. Satellites orbiting in LEO are faster than earth's rotation. As a result, they stay over area-of-interest only for a very short time and revisit (successive observation by same satellite) may take days. In the case of GISAT, the time delay between successive observation of two different targets is only limited to the time taken to steer the satellite and data rate.
Civilian Applications :
- Near real-time monitoring of disasters and coordination of relief efforts
- Agriculture planning
- Meteorological observations
- Environmental monitoring
Military Application :
With 50m resolution GISAT will be able to detect and classify large naval ships. Another application of Infrared imaging could be the detection of the enemy aircraft (afterburner heat) and missile launches.
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