Isro successfully launches Gisat-1A (EOS-05) satellite on GSLV-F17

Gisat-1A is the programme's second attempt, and its success finally gives India the capability that Gisat-1 was meant to establish.

BENGALURU: When Isro’s GSLV-F17 lifted off from Sriharikota early Friday and successfully placed Gisat-1A or EOS-05 into its intended orbit, the mission did more than add another Earth observation satellite to India’s growing fleet. It ended a difficult chapter for a programme that had been repeatedly delayed and then lost in space, gave Isro its first successful launch of 2026, and put the agency back on the launch pad after its previous mission, PSLV-C62, failed on Jan 12. For Isro, the successful launch of Gisat-1A is therefore both a technical and psychological milestone. The GSLV-F17 precisely injected the 2,367kg satellite into its intended orbit in the 19th mission of the GSLV and the 107th launch from Sriharikota. But the significance of the mission is best understood through both the troubled history of the Gisat programme and what the satellite adds to India's capabilities.

Breaking Gisat Jinx

India’s attempt to place an imaging satellite in geostationary orbit (GEO) has been marked by setbacks for more than six years. The original Gisat-1, later designated EOS-03, was scheduled to launch on March 5, 2020. The mission was scrubbed shortly before the countdown was to begin. A subsequent launch planned for 2021 was also delayed because of a voltage problem. When the satellite finally lifted off aboard GSLV-F10 on Aug 12, 2021, the first two stages performed normally. But the cryogenic upper stage (CUS) failed to ignite because of a technical anomaly, resulting in the loss of the satellite. Gisat-1A is the programme's second attempt, and its success finally gives India the capability that Gisat-1 was meant to establish. “It gives a little more than what Gisat-1 would have,” a senior scientist said.

What Gisat-1A Gives

Most Indian Earth observation satellites operate in low-Earth orbit, circling the planet roughly every 90 minutes. They can provide high-resolution images, but their ability to observe a particular location depends on when the satellite passes overhead. Gisat-1A operates from a geosynchronous vantage point about 36,000km above Earth. Instead of repeatedly flying over India and moving away, it can continuously watch the Indian subcontinent and surrounding region. That geometry involves a trade-off. Observing from such a great distance does not offer the same level of spatial detail that specialised LEO satellites can provide. What it offers instead is persistence: the ability to repeatedly image very large areas and watch fast-changing events as they develop. Once operationalised, EOS-05 will become India’s first dedicated imaging satellite from geo-orbit. Isro chairman V Narayanan said it would provide “strategic data” for the country. Narayanan also stressed its civilian purpose: “The satellite will continuously scan India for safety, security of citizens, it’s not a ‘spy satellite’.” But the same persistent, wide-area observation that makes the satellite useful for civilian applications also gives the data strategic value. The satellite can be used to monitor specific regions of interest along India’s borders on both the Western and Northern sectors.

From disasters to national security

One of the most immediate uses of such a capability is disaster monitoring. Cyclones over the Bay of Bengal or Arabian Sea, rapidly evolving cloud systems, floods, forest fires and other events can change significantly between successive passes of conventional Earth observation satellites. A geosynchronous imaging satellite can repeatedly observe the same broad region, allowing agencies to follow developments more closely. This can help track storm evolution, monitor the spread of flooding, observe fire and smoke patterns, and provide updated information during fast-moving emergencies. Such repeated observations could also support response agencies in prioritising evacuations and relief operations. The capability has longer-term civilian applications too. Agriculture, drought progression, snow cover, glaciers, water bodies and other environmental indicators can be observed repeatedly over large areas, supplementing India's existing Earth observation systems. For planners, the value lies not just in obtaining an image, but in seeing how conditions change. The “strategic data” reference also reflects the dual-use nature of Earth observation. Persistent monitoring of large areas can contribute to better situational awareness during security crises, while observation of surrounding seas and maritime approaches can complement other systems used to monitor economic activity, environmental events and unusual developments.

Morale boost after a difficult start

The timing of the success is equally important. Isro’s last launch attempt before Thursday was the PSLV-C62 mission on Jan 12, which failed. That left the agency without a successful launch for nearly eight months and made Gisat-1A its first success of 2026. A launch failure involving one vehicle does not necessarily indicate a problem with other launch systems. But after a long gap — waiting for clearance from Govt for launch of other missions as PSLV went under review — without a successful mission, the next launch inevitably carries greater institutional pressure. Gisat-1A has now broken that sequence. The mission also reinforces confidence in the GSLV-Mk2, whose cryogenic upper stage had been at the centre of the 2021 Gisat-1 failure. Since then, the vehicle has recorded successive successful missions, including the launch of the joint Nasa-Isro Nisar satellite in July 2025. The successful GSLV-F17 mission adds another flight to that record. The 2,367kg Gisat-1A is the heaviest satellite meant to reach a Geostationary Transfer Orbit (GTO) — a highly elliptical temporary orbit used to deliver satellites from Earth up to a high GEO — Isro has mounted on a GSLV-family rocket. However, it is noteworthy that the targeted orbit for the launch itself was a sub-GTO orbit, 6,000-12,000km lower apogee (farthest point from Earth) than a nominal GTO, which allows for the additional payload weight. Earlier, Isro has more than once put a 2,200-class satellite into GTO using this family of rockets. Isro is now preparing for a demanding final phase of 2026, with missions including the first uncrewed Gaganyaan flight and the launch of navigation satellite NVS-03 in the pipeline. In that sense, Gisat-1A is more than the successful return of one satellite programme. It gives Isro something it needed after the Jan 12 failure and months away from the launch pad: momentum. For India, it finally delivers a capability first attempted in 2020 and lost in 2021. For Isro, it closes the Gisat chapter on a success and opens the next phase of its 2026 launch campaign with some of its most consequential missions still ahead.