On May 18, 2025, the Indian Space Research Organisation (ISRO) faced a major setback with the PSLV-C61 mission, which was intended to launch the Earth Observation Satellite (EOS-09) into a sun-synchronous polar orbit from the Satish Dhawan Space Centre in Sriharikota.

The mission marked ISRO’s 101st launch from the facility and the 63rd flight of its highly reliable Polar Satellite Launch Vehicle (PSLV), this time in the XL configuration.

The PSLV-C61, standing 44.5 meters tall and weighing 321 tons at lift-off, was carrying the heaviest satellite ever built by ISRO, signalling the organisation’s readiness for even more ambitious missions such as Gaganyaan, Chandrayaan-5, and Mangalyaan in the near future.

The launch commenced precisely at 5:59 am IST and initially proceeded flawlessly, with the first and second stages performing nominally. However, during the operation of the third stage, ISRO Chairman V Narayanan announced that an anomaly had been observed-a pressure issue in the third stage motor. 

This technical problem prevented the vehicle from achieving its intended orbit, and as a result, the mission objectives could not be accomplished. The announcement came shortly after the launch, around 6:15 am, when the mission director officially declared the mission a failure.

The PSLV’s third stage is a critical component, responsible for imparting the necessary velocity to place the payload into its designated orbit. Any pressure anomaly in this stage can lead to insufficient thrust or improper trajectory, jeopardising the satellite’s deployment. While the specific details of the anomaly were not immediately disclosed, Chairman Narayanan assured that the situation was under discussion and further information would be provided after a thorough analysis.

This incident is a rare setback for ISRO, which has built a reputation for reliability and success in satellite launches, especially with the PSLV series. The failure is particularly disappointing given the mission’s significance: EOS-09 was designed as an all-weather military grade earth observation satellite, expected to bolster India’s remote espionage capabilities. The mission’s failure underscores the inherent challenges and complexities of space exploration, even for seasoned organisations like ISRO.

Despite this setback, ISRO’s commitment to transparency and its resolve to investigate and address the issue reflect its robust organizational ethos. The lessons learned from the PSLV-C61 mission will undoubtedly contribute to future improvements, ensuring the continued progress of India’s ambitious space program. As ISRO prepares for landmark missions such as Gaganyaan, Chandrayaan-5, and Mangalyaan, the agency’s resilience and dedication to scientific excellence remain undiminished.

PTI