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GSLV-F17 places EOS-05, India's first geosynchronous imaging satellite, in transfer orbit

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First brief 4 Sep, 10:55 am IST Updated 8 Sep, 2:56 am IST 5 developments 3 min read Latest ↓

File: GSLV rollout, Sriharikota — Indian Space Research Organisation · GODL-India

Where it stands

EOS-05 completed its third and final orbit-raising manoeuvre on 7 September 2026. ISRO said the operation ended at 8:57 pm IST. The satellite’s Liquid Apogee Motor fired for 1,247 seconds to raise the perigee. The estimated orbit was 34,903 km by 35,884 km. ISRO reported normal health. GSLV-F17 launched the satellite on 4 September, followed by orbit-raising operations on 5, 6 and 7 September. The new notice reports a completed manoeuvre, not a declaration that imaging services are operational.

Background

Most Earth imaging satellites use low or sun-synchronous orbits. Low-orbit satellites pass over the same place at intervals. A geosynchronous satellite completes one orbit in the time Earth takes to rotate once. The satellite can therefore observe the same broad region repeatedly. A transfer orbit is only an intermediate path. The spacecraft uses its own propulsion to raise and shape the final orbit. GSLV uses three stages. The GSLV third stage uses liquid hydrogen and liquid oxygen at very low temperatures.

How it developed

4 September 2026, 2:55 am

How it started
GSLV-F17 lifts off from Sriharikota with the 2,367 kg EOS-05

GSLV-F17 lifted off at 2:55 am on 4 September 2026. The rocket departed from the second launch pad at Sriharikota. The rocket carried the 2,367 kg EOS-05 Earth observation spacecraft.

Indian Space Research Organisation Akashvani News Business Standard
4 September 2026, about 18 minutes after lift-off

New fact
Rocket places EOS-05 in the intended sub-geosynchronous transfer orbit

GSLV-F17 placed EOS-05 in its intended orbit after lift-off. The nominal transfer orbit has a 170 km perigee and a 28,934 km apogee. The elliptical path is not the satellite's final working orbit.

Indian Space Research Organisation
4 September 2026

Consequence
EOS-05 becomes India's first imaging satellite for geosynchronous orbit

ISRO describes EOS-05 as a state-of-the-art Earth observation spacecraft. EOS-05 is India's first imaging satellite designed for geosynchronous orbit. The successful insertion starts the spacecraft's journey towards its working orbit.

Indian Space Research Organisation
5 September 2026, 8.19 pm

New fact
EOS-05 completes its first orbit-raising burn, ISRO says

ISRO said EOS-05's Liquid Apogee Motor fired for 5,406.4 seconds on 5 September 2026. The planned first orbit manoeuvre ended at 20:19 hours Indian time. The orbit after the burn is '20000 km x 31129 km', as stated by ISRO. ISRO said more manoeuvres in the coming days will place EOS-05 in geosynchronous orbit. The final position is the 85.5° East orbital slot. ThePrint reported on 4 September 2026 that GSLV-F17 placed EOS-05 higher than planned.

Indian Space Research Organisation ThePrint
6 September 2026, 7:00 pm IST

New fact
EOS-05 completes second orbit-raising burn; health is normal

ISRO completed EOS-05's second orbit-raising operation at 7:00 pm IST on 6 September 2026. The Liquid Apogee Motor fired for 338.9 seconds, raising the estimated apogee to 35,786 km. ISRO said the satellite's health was normal; this update does not announce arrival at the final operating orbit.

Indian Space Research Organisation
7 September 2026, 8:57 pm IST

New fact
EOS-05 completes its third and final orbit-raising manoeuvre

ISRO completed EOS-05’s third and final orbit-raising manoeuvre at 8:57 pm IST on 7 September 2026. The Liquid Apogee Motor fired for 1,247 seconds to raise the perigee. ISRO estimated the resulting orbit at 34,903 km by 35,884 km and reported normal satellite health. Perigee is the orbit’s closest point to Earth; apogee is the farthest. This notice does not declare the satellite operational.

Indian Space Research Organisation

Why it matters for UPSC

GS3 · Space technologyGS3 · Earth observationPrelims · Orbits and launch vehicles

For GS3, distinguish launch, orbit adjustment and operational service. For Prelims, perigee is the closest point to Earth and apogee is the farthest. Every geostationary orbit is geosynchronous, but a geosynchronous orbit need not appear fixed over one point.

Key terms

Geosynchronous Satellite Launch Vehicle (GSLV)GSLV is an Indian launch vehicle for placing heavier satellites into high transfer orbits. GSLV-F17 was the 19th GSLV flight. The rocket is 51.7 metres high and has three stages. The lift-off mass was about 420.5 tonnes. The final CUS15 stage is cryogenic.

Geosynchronous orbitA satellite in geosynchronous orbit takes one sidereal day to circle Earth. A sidereal day is about 23 hours and 56 minutes. The satellite returns to the same position in the sky at the same time each day. A geosynchronous path need not be circular or directly above the equator.

Geostationary orbitA geostationary orbit is a special geosynchronous orbit. The orbit is circular and lies above the equator. The satellite moves in the same direction as Earth's rotation. The satellite therefore appears fixed above one longitude.

Sub-geosynchronous transfer orbitA transfer orbit is an intermediate elliptical orbit. GSLV-F17 placed EOS-05 in a sub-geosynchronous transfer orbit. ISRO's nominal figures were a 170 km perigee and a 28,934 km apogee. EOS-05 must use onboard propulsion to move towards its working orbit.

Earth observation satelliteAn Earth observation satellite collects images or measurements of Earth's land, water and atmosphere. Governments use such data for mapping, resource management, weather services and disaster response. EOS-05 is India's first imaging satellite designed to work from geosynchronous orbit.

Cryogenic upper stageA cryogenic stage burns propellants stored at extremely low temperatures. The GSLV CUS15 stage uses liquid hydrogen and liquid oxygen. Cryogenic propulsion gives the upper stage the efficiency needed for high-energy satellite missions.

Liquid Apogee Motor (LAM)The Liquid Apogee Motor is the satellite's own rocket engine. The engine burns liquid fuel to push the satellite into a higher orbit. EOS-05 fired the motor for 5,406.4 seconds on 5 September 2026, ISRO said.

Orbital slotAn orbital slot is a fixed position in the geosynchronous belt above the equator. Each slot is named by its longitude. Slots are assigned so that satellites do not interfere with each other. EOS-05 will take the 85.5° East slot.

Sources (8)

Indian Space Research Organisation · official · GSLV-F17/EOS-05 mission page4 Sep, 10:50 am
Business Standard · ISRO launches EOS-05, India's first imaging satellite in geosynchronous orbit4 Sep, 10:50 am
Akashvani News · official · ISRO successfully launches EOS-05 from Sriharikota4 Sep, 10:50 am
Indian Space Research Organisation · official · GSLV-F17/EOS-05 mission brochure4 Sep, 10:50 am
Indian Space Research Organisation · official · Orbit manoeuvring of EOS-05 spacecraft (5 September 2026)6 Sep, 2:20 am
ThePrint · ISRO's 'naughty boy' performs better than expected: what it means for the EOS-05 satellite (4 September 2026)6 Sep, 2:20 am
Indian Space Research Organisation · official · Second orbit manoeuvring of EOS-05 (6 September 2026)7 Sep, 10:06 am
Indian Space Research Organisation · official · Third and final orbit manoeuvring of EOS-05 (7 September 2026)8 Sep, 2:53 am

GSLV-F17 places EOS-05, India's first geosynchronous imaging satellite, in transfer orbit

Where it stands

Background

How it developed

GSLV-F17 lifts off from Sriharikota with the 2,367 kg EOS-05

Rocket places EOS-05 in the intended sub-geosynchronous transfer orbit

EOS-05 becomes India's first imaging satellite for geosynchronous orbit

EOS-05 completes its first orbit-raising burn, ISRO says

EOS-05 completes second orbit-raising burn; health is normal

EOS-05 completes its third and final orbit-raising manoeuvre

Why it matters for UPSC

Key terms