ISRO Successfully Completes Final EOS-05 Orbit-Raising Manoeuvre

The Indian Space Research Organisation has successfully completed the third and final orbit-raising manoeuvre of the EOS-05 Earth-observation satellite, bringing India’s newest geosynchronous imaging spacecraft close to its intended operational orbit.

The final manoeuvre was completed at 8:57 pm on September 7, 2026. According to ISRO, the satellite’s Liquid Apogee Motor, or LAM, fired for 1,247 seconds, raising the spacecraft’s perigee and placing EOS-05 in an estimated orbit of 34,903 km × 35,884 km. ISRO confirmed after the operation that the satellite’s health remained normal.

The successful operation concludes a carefully sequenced series of orbital manoeuvres conducted over three days following the satellite’s launch aboard GSLV-F17 on September 4.

EOS-05 is particularly significant because ISRO describes it as India’s first imaging satellite designed to operate from geosynchronous orbit. Unlike most Indian Earth-observation satellites, which operate much closer to Earth in low-Earth or sun-synchronous orbits, EOS-05 is being positioned approximately 36,000 kilometres above the planet, allowing it to continuously observe a very large region from its assigned orbital location.

GSLV-F17 Begins the Journey

EOS-05 was launched from the Second Launch Pad at the Satish Dhawan Space Centre in Sriharikota aboard GSLV-F17 in the early hours of September 4.

The mission marked the 19th flight of India’s Geosynchronous Satellite Launch Vehicle. ISRO confirmed that GSLV-F17 successfully placed EOS-05 into its intended Sub-Geosynchronous Transfer Orbit, establishing the initial trajectory from which the spacecraft could progressively raise and circularise its orbit using its own propulsion system.

The launch vehicle’s role ended after spacecraft separation. From that point onward, EOS-05’s onboard propulsion system assumed responsibility for moving the satellite toward its final geosynchronous position.

This process is standard for satellites launched into transfer orbits. Instead of requiring the launch vehicle to place a heavy spacecraft directly into a circular orbit near 36,000 km altitude, the rocket injects it into an intermediate elliptical orbit. The spacecraft subsequently fires its own apogee motor at carefully selected points to progressively change the orbit.

For EOS-05, ISRO planned three major manoeuvres between September 5 and September 7.

First Manoeuvre Produces Major Increase in Orbital Altitude

The first orbit-raising operation took place at 8:19 pm on September 5.

It was by far the longest of the three burns. EOS-05’s LAM operated for 5,406.4 seconds, or roughly 90 minutes. Following the manoeuvre, ISRO estimated the spacecraft’s orbit at 20,000 km × 31,129 km.

ISRO stated at the time that further manoeuvres would eventually position EOS-05 in geosynchronous orbit at the 85.5° East orbital slot.

The long first burn therefore accomplished much of the initial orbital energy increase required after the spacecraft’s Sub-GTO injection.

Second Manoeuvre Raises the Apogee

The second operation followed on September 6 at 7:00 pm.

During this manoeuvre, the LAM fired for 338.9 seconds. ISRO reported that the operation successfully raised the spacecraft’s apogee to an estimated 35,786 km, placing the high point of EOS-05’s orbit close to geosynchronous altitude. The agency again confirmed that the satellite remained healthy following the burn.

With the apogee close to its required altitude, the remaining task was principally to raise the lower point of the orbit, or perigee, so that EOS-05 could enter an almost circular geosynchronous orbit.

That was achieved through the third manoeuvre on September 7.

Final Burn Brings EOS-05 Close to Circular Geosynchronous Orbit

The final 1,247-second engine firing substantially increased EOS-05’s perigee.

The resulting 34,903 km × 35,884 km orbit is now close to circular and close to the approximately 35,786-km altitude associated with geosynchronous operation.

The progression illustrates how dramatically the orbit changed over just three days.

Following the September 5 manoeuvre, the spacecraft’s perigee remained at roughly 20,000 km. By the evening of September 7, that figure had risen to nearly 35,000 km while the apogee approached 35,900 km.

With the major orbit-raising phase completed, EOS-05 can proceed through the remaining stages required before operational utilisation, including orbital positioning, spacecraft configuration and payload-related activities.

ISRO has not yet announced completion of the satellite’s commissioning process, so the successful final manoeuvre should not be confused with the beginning of full operational imaging.

A Different Kind of Indian Earth-Observation Satellite

EOS-05 stands apart from most of India’s previous remote-sensing spacecraft because of the orbit from which it is designed to operate.

ISRO officially describes EOS-05 as a state-of-the-art Earth-observation spacecraft and India’s first-ever imaging satellite from geosynchronous orbit.

Most high-resolution Earth-observation satellites operate in relatively low orbits. As they circle Earth, they pass over different regions and collect imagery along their ground tracks. Such orbits offer advantages in spatial resolution because the spacecraft operates relatively close to the surface.

A geosynchronous imaging satellite offers a different capability.

Operating near 36,000 km altitude and moving in synchronisation with Earth’s rotation allows a spacecraft to maintain persistent visibility over a very large geographical region. This can provide an important advantage when repeated or sustained observation is more important than simply obtaining a single image during a satellite pass.

The 85.5° East orbital location identified by ISRO places EOS-05 in a position suitable for observing India and surrounding regions from geosynchronous altitude.

The precise operational capabilities, imaging modes and utilisation strategy will become clearer as ISRO completes the spacecraft’s commissioning and begins releasing mission data.

Another Successful GSLV Mission

EOS-05 also adds another successful flight to India’s GSLV programme.

GSLV-F17 was the 19th GSLV mission, following GSLV-F16, which launched the joint NASA-ISRO NISAR satellite in July 2025.

The GSLV family occupies an important position between India’s highly experienced PSLV and the heavier LVM3. Its indigenous cryogenic upper stage enables the vehicle to inject larger spacecraft into the high-energy transfer orbits required for geosynchronous missions.

For EOS-05, GSLV-F17 performed the critical first stage of the orbital journey successfully by placing the spacecraft into Sub-GTO. The satellite’s onboard propulsion system then completed the transition through three precisely executed burns.

The sequence therefore demonstrates not only launch-vehicle performance but also spacecraft propulsion, navigation, tracking and mission-control capability.

EOS-05 Moves Into the Next Phase

With the final major orbit-raising manoeuvre complete and spacecraft health reported as normal, EOS-05 has crossed one of the most important post-launch phases of its mission.

The sequence has unfolded rapidly: launch on September 4, the first orbit manoeuvre on September 5, the second on September 6 and the final manoeuvre on September 7.

The successful completion of the orbital-raising campaign is therefore more than a routine post-launch milestone. It brings India closer to operating a new class of indigenous Earth-observation spacecraft capable of observing the planet from geosynchronous altitude and expands the range of orbital architectures available to the country’s increasingly sophisticated space programme.

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