ISRO's launch of India's first imaging satellite will help keep a permanent eye on its border from 36,000 km away

ISRO’s EOS-05 is set to give India a new kind of view from space when the Earth observation satellite launches aboard the GSLV-F17 mission from Sriharikota at 2:55 am on September 4. Positioned in geosynchronous orbit around 36,000 km above Earth, the satellite is designed to repeatedly observe the same region continuously rather than capture brief snapshots while passing overhead, according to a TOI report.

ISRO has described EOS-05, also known as Gisat-1A, as India’s first state-of-the-art imaging satellite from geosynchronous orbit. Its ability to maintain persistent coverage could support monitoring of the Indian subcontinent, including remote border areas, strategic assets, severe weather and environmental events. The satellite is intended for both civilian and military applications.

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Why EOS-05’s orbit matters for India

Most of India’s Earth observation and imaging satellites, including the Cartosat and Risat series, operate in low Earth orbit, generally between 60 km and 2,000 km.

A GEO satellite offers a fundamentally different advantage. At roughly 36,000 km altitude, a satellite can match Earth’s rotational speed and remain positioned over the same location. That allows it to maintain a continuous view of a particular part of the planet rather than returning to the same area only after completing multiple orbits.

For EOS-05, this means the satellite can provide ongoing observation of a fixed region and track rapidly changing events such as severe storms, lightning and fires.

Once operational, the spacecraft is therefore expected to function as a persistent “eye in the sky” over the Indian subcontinent, providing uninterrupted observation rather than occasional imagery.

GEO vs LEO: What changes in satellite surveillance?

Satellites placed in LEO or even sun-synchronous orbit travel around Earth while the planet rotates beneath them. As a result, a particular location may not be visible again until the satellite makes another pass, with the revisit potentially taking days.

A geosynchronous imaging platform works differently. By operating at a much higher altitude and moving in sync with Earth’s rotation, it can continue watching the same broad region.

This distinction is particularly useful for applications where changes need to be observed as they happen. Instead of relying on separate images collected during periodic passes, a GEO-based system can follow the evolution of an event over time.

EOS-05 carries two multispectral imagers

The satellite is equipped with two multispectral imagers designed to produce detailed observations of Earth.

One of the cameras has a spatial resolution of 42 metres per pixel, which, according to the information provided, will make it the highest-resolution camera ever placed in geostationary orbit.

EOS-05 is intended to collect detailed imagery and generate data for Earth monitoring and other uses requiring frequent observation of land and environmental conditions.

The combination of persistent coverage and multispectral imaging is expected to expand the type of information that can be collected from a geostationary vantage point.

EOS-05 follows the failed Gisat-1 mission

The upcoming spacecraft also marks a return to an earlier effort to place an Indian Earth-imaging satellite in geostationary orbit.

EOS-05, or Gisat-1A, is set to replace Gisat-1, which was lost during launch on August 12, 2021. The mission failed after a technical anomaly in the cryogenic upper stage of the GSLV-F10 rocket prevented proper ignition.

Had that launch succeeded, Gisat-1 would have become India’s first Earth-imaging satellite operating from geostationary orbit.

The new mission therefore carries both a technological objective and the significance of revisiting an earlier attempt.

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GSLV-F17 marks ISRO’s return after launch break

The September 4 launch is also notable for ISRO’s launch schedule. The GSLV-F17 mission from Sriharikota will mark the agency’s major return to the launchpad after a break of nearly eight months.

With EOS-05, ISRO is attempting to add a new persistent Earth-observation capability to its satellite fleet, combining a geosynchronous orbit with high-resolution multispectral imaging and continuous monitoring of the same region.