What Makes This Satellite a 'First'?
While India has a sophisticated fleet of Earth observation satellites, they have traditionally operated in Low Earth Orbits (LEO). These satellites, like those in the Cartosat series, fly a few hundred kilometres above the planet, capturing extremely
high-resolution images. However, because they are constantly moving around the globe, they can only revisit a specific location after a few days. EOS-05 is different. It is India's first dedicated imaging satellite designed to operate from a geosynchronous orbit, roughly 36,000 kilometres away. This mission successfully realises a goal that ISRO has pursued for years, most notably with the GISAT-1 (also known as EOS-03) mission, which was lost due to a launch vehicle failure in August 2021. The success of EOS-05, also known as GISAT-1A, finally delivers this long-awaited capability.
The Geosynchronous Advantage Explained
A satellite in a geosynchronous orbit has an orbital period that matches Earth's rotation. From our perspective on the ground, this allows the satellite to remain over the same broad region continuously. If a satellite is also placed directly above the equator in a circular orbit, it becomes 'geostationary,' appearing fixed in the sky. This is the principle used by communication and DTH television satellites. By placing an imaging satellite like EOS-05 in such a high orbit, ISRO gains the ability to monitor a large area of the Indian subcontinent and its surroundings almost constantly. Instead of getting a snapshot of a location every few days, EOS-05 can provide images of a selected area every five minutes, and of the entire Indian landmass every 30 minutes. This is a game-changer for tracking rapidly developing events.
A Powerful Eye in the Sky
Dubbed the 'Eye in the Sky,' the 2,367 kg EOS-05 satellite is equipped with state-of-the-art imaging instruments. It carries multi-spectral and hyperspectral cameras that can see in various wavelengths of light, beyond what is visible to the human eye. This allows it to gather detailed information about the Earth's surface. One of its imagers has a spatial resolution of 42 metres, which is considered very high for a satellite positioned so far away. While satellites in lower orbits provide finer detail, the strength of EOS-05 is not pinpoint resolution but its constant watchfulness over a vast area. The satellite was launched aboard ISRO's GSLV-F17 rocket and subsequently placed into its final orbital slot through a series of complex manoeuvres conducted by ISRO's ground control.
Applications for Nation Building and Security
The capabilities of EOS-05 have wide-ranging applications for both civilian and strategic purposes. For disaster management, it is an invaluable asset. The satellite can provide near real-time imagery of natural disasters like cyclones, floods, forest fires, and landslides, enabling authorities to respond faster and more effectively. Its frequent revisit capability can help monitor the progression of a flood or the spread of a wildfire. In agriculture, it can be used for monitoring crop health, assessing soil conditions, and predicting yields on a large scale. Beyond these civilian uses, ISRO has also described the satellite as having strategic importance. The ability to continuously monitor borders, ports, and maritime areas provides a significant boost to the nation's security and surveillance architecture.
