GISAT-1A, also designated EOS-05, is ISRO’s agile geo-imaging Earth observation satellite designed to operate from geostationary orbit, about 36,000 km above the equator, so that it stays fixed over the Indian subcontinent and provides continuous, near real-time imagery. ISRO is preparing to launch it on the GSLV-F17 (GSLV Mk-II) rocket, giving India a second attempt at a capability lost when GISAT-1 failed to reach orbit in 2021.
Context
- ISRO is preparing to launch GISAT-1A (EOS-05) aboard GSLV-F17, a GSLV Mk-II with the indigenous CE-7.5 cryogenic upper stage and a 4-metre Ogive payload fairing.
- The first satellite of the series, GISAT-1 (EOS-03), was lost on 12 August 2021 when the cryogenic upper stage of GSLV-F10 failed to ignite.
What GISAT-1A Is
- An agile Geo-Imaging Satellite in geostationary orbit – the satellite’s orbital period matches the Earth’s rotation, so it appears fixed above one point on the equator.
- Key difference from ordinary remote-sensing satellites: conventional Earth observation satellites (Cartosat, Resourcesat, RISAT) fly in low Earth orbit at 500-900 km, circling the planet and revisiting a given place only every few days. GISAT-1A stays over India and can image the same region repeatedly through the day.
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Purpose
- Near real-time, high-frequency imaging of the Indian subcontinent and surrounding seas.
- Disaster monitoring: cyclones, floods, forest fires and cloudbursts as they develop.
- Agriculture and forestry: crop condition, drought and vegetation monitoring in near real time.
- Security: continuous surveillance of borders and the Indian Ocean region.
The Launch Vehicle
- GSLV Mk-II is ISRO’s three-stage medium-lift rocket – a solid first stage with liquid strap-ons, a liquid second stage and the indigenous CE-7.5 cryogenic upper stage – that carries about 2.2 tonnes to geosynchronous transfer orbit.
- The larger 4-metre Ogive fairing accommodates the satellite’s large aperture.
Important Facts for Examsmost asked
- GISAT-1A = EOS-05; agency ISRO; orbit geostationary (about 36,000 km); launch vehicle GSLV-F17 (GSLV Mk-II).
- First geo-imaging satellite GISAT-1 (EOS-03) failed on GSLV-F10, 12 August 2021 (cryogenic stage anomaly).
- EOS series = ISRO’s renamed Earth observation satellites; LEO satellites revisit periodically, a GEO imager watches continuously.
FAQs
Why put an Earth observation satellite in geostationary orbit?
For continuous coverage: a LEO satellite passes over India only a few times a day, while a GEO satellite can image the subcontinent every few minutes – essential for tracking fast-moving disasters.
What is the trade-off?
Distance. From 36,000 km the ground resolution is coarser than from LEO, so GISAT complements, rather than replaces, high-resolution Cartosat-class satellites.
Why is GISAT-1A important for exams?
It combines ISRO’s GSLV programme, the EOS naming series and disaster-management applications – all frequent question areas.
