What Is GISAT-1? EOS-05 Set to Give India a New Eye in Space

India is preparing to launch EOS-05 on September 4, marking a major step in its effort to strengthen continuous Earth-imaging capabilities from geostationary orbit. The satellite is designed as the successor to the earlier GISAT-1 mission, which was lost during a launch attempt in 2021.

EOS-05 is scheduled to fly aboard the GSLV-F17 rocket from the Second Launch Pad at the Satish Dhawan Space Centre in Sriharikota. The mission aims to place an advanced Earth observation satellite in geostationary orbit, enabling repeated monitoring of India and nearby regions.

GISAT stands for Geo Imaging Satellite. The concept was developed to provide India with a persistent view of large areas of the Earth's surface. Unlike Earth observation satellites in low-Earth orbit, which see a particular location only when they pass over it, a geostationary satellite can remain positioned over roughly the same region.

EOS-05 is planned to operate at an altitude of approximately 36,000 kilometres above the equator. At this distance, its orbital period matches Earth's rotation, allowing the satellite to appear almost stationary relative to the ground.

This orbital position will enable EOS-05 to repeatedly capture images of the Indian subcontinent and surrounding areas. Its planned imaging capability could provide observations at intervals of about 30 minutes, while priority locations may potentially be monitored at intervals as short as five minutes.

Such frequent observations could be particularly useful for tracking rapidly changing situations. Weather systems, cyclones, floods and forest fires can develop or change quickly, making frequent satellite observations valuable for monitoring and response efforts.

Earth observation satellites also play an important role in agriculture, environmental monitoring and disaster management. They can help track changes in farmland, water bodies and land use while providing information about developing weather and natural disasters.

EOS-05 could additionally strengthen India's ability to maintain persistent observation of strategically important areas. Continuous or near-continuous imaging can provide a different capability from satellites that only observe locations during periodic passes.

Operating an imaging satellite from geostationary orbit presents significant technological challenges. At nearly 36,000 kilometres from Earth, the spacecraft must capture detailed images over an enormous area while maintaining accurate pointing, stable operations and reliable image acquisition.

The upcoming mission also represents a renewed attempt at the GISAT concept after the failure of the original GISAT-1 mission. GISAT-1 was lost when the GSLV-F10 launch failed to place the satellite into orbit in August 2021.

Five years later, EOS-05 is set to revive the objective through a new mission. If the September 4 launch and subsequent operations are successful, the satellite could provide India with a powerful new capability for near-continuous Earth observation from space.