ISRO EOS-05 Reaches Intended Geosynchronous Orbit After Final Orbit-Raising Manoeuvre

India's latest Earth-observation satellite, EOS-05, has successfully reached its intended geosynchronous orbit after ISRO completed the third and final orbit-raising manoeuvre.

The final manoeuvre was carried out using the satellite's Liquid Apogee Motor, which fired for 1,247 seconds from 8:57 pm on September 7. The operation placed EOS-05 into a near-circular orbit at an altitude of around 35,000 kilometres.

ISRO confirmed that the spacecraft remains healthy and is functioning as expected in orbit. While EOS-05 has completed a major stage of its journey, further activities are required before the satellite begins regular Earth-observation operations.

EOS-05 was launched from Sriharikota at 2:55 am on September 4 aboard the GSLV-F17 rocket. Weighing 2,367 kg, the satellite is the heaviest payload carried by the GSLV so far.

The satellite was initially deployed into a sub-geosynchronous transfer orbit rather than being placed directly into its final operational orbit. It subsequently used its onboard Liquid Apogee Motor to gradually raise its orbit through a series of manoeuvres.

The first orbit-raising manoeuvre on September 5 lasted 5,406.4 seconds and raised the satellite's orbit to an estimated 20,000 km by 31,129 km. A second manoeuvre on September 6 further increased the apogee to approximately 35,786 km.

The final manoeuvre on September 7 raised the perigee and placed EOS-05 into a near-circular orbit of around 34,903 km by 35,884 km. The satellite is expected to eventually operate from its designated 85.5° East orbital position.

EOS-05 is India's first imaging satellite designed to operate from geosynchronous orbit. Positioned at an altitude of approximately 36,000 km above Earth, the satellite can observe broadly the same region as the planet rotates, offering a different capability compared with conventional Earth-imaging satellites operating in low-Earth orbit.

The geosynchronous position is expected to allow EOS-05 to repeatedly observe large portions of the Indian subcontinent without waiting for the satellite to make another pass over a particular region.

The satellite is designed to capture images of broad areas at intervals of around 30 minutes, while priority locations can potentially be revisited in as little as five minutes.

This rapid observation capability could support the monitoring of fast-changing events such as cyclones, floods and forest fires. EOS-05 is also designed for applications related to agriculture, forestry, water resources and other Earth-observation requirements.