ISRO PSLV-C61 Mission Fails to Deploy EOS-09 Satellite
Sriharikota, India – May 18, 2025 – The Indian Space Research Organisation (ISRO) faced a rare setback as its 101st mission, the PSLV-C61, failed to place the Earth Observation Satellite (EOS-09) into its intended Sun Synchronous Polar Orbit (SSPO) on Sunday morning. The launch, which took place at 5:59 AM IST from the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh, encountered a critical anomaly in the rocket’s third stage, resulting in mission failure.
Mission Details and Failure
The PSLV-C61, the 63rd flight of ISRO’s trusted Polar Satellite Launch Vehicle and the 27th in its XL configuration, was tasked with deploying the 1,696.24 kg EOS-09 satellite, also known as RISAT-1B. The satellite, equipped with a C-band Synthetic Aperture Radar (SAR), was designed to provide all-weather, day-and-night imaging for applications such as agriculture, forestry, disaster management, and national security.
ISRO Chairman V. Narayanan addressed the media post-launch, stating, “The PSLV is a four-stage vehicle, and up to the second stage, the performance was normal. The third stage motor ignited perfectly; however, during its operation, we observed a fall in chamber pressure, and the mission could not be accomplished.” Initial analysis points to a suspected flex nozzle malfunction in the third-stage propulsion system, which uses Hydroxyl-Terminated Polybutadiene (HTPB) solid fuel to generate 240 kN of thrust.
ISRO’s official statement on X read, “Today 101st launch was attempted, PSLV-C61 performance was normal till 2nd stage. Due to an observation in 3rd stage, the mission could not be accomplished.” The satellite failed to reach its intended 525 km orbit, and its status remains unclear, with ISRO yet to confirm whether it was damaged or placed in an incorrect orbit.
Significance of EOS-09
EOS-09 was a follow-on to the EOS-04 satellite launched in 2022, designed to enhance India’s remote sensing capabilities. Its advanced SAR enabled high-resolution imaging through clouds and darkness, complementing ISRO’s fleet of satellites like Resourcesat, Cartosat, and RISAT-2B. The satellite, with a mission life of five years, was also equipped with deorbiting fuel to ensure safe disposal, aligning with ISRO’s commitment to sustainable space practices.
A Rare Setback for PSLV
This marks only the third failure in 63 PSLV missions, underscoring the rocket’s reliability. Previous failures include the PSLV-D1 in 1993, due to stage separation and control issues, and a 2017 mission where the payload fairing failed to separate. Space scientist PK Ghosh commented, “While it’s an unfortunate incident, it should not be seen as a major setback, given ISRO’s minimal setbacks compared to other space agencies.”
Next Steps
ISRO has initiated a detailed investigation to identify the root cause of the third-stage anomaly. Former ISRO scientists note that the Failure Analysis Committee (FAC) will examine telemetry data, including the sharp decline in velocity (from 6 km/s to 2.45 km/s) and trajectory deviations, to pinpoint the issue. Chairman Narayanan assured, “We are studying the entire performance, and we shall come back at the earliest.” ISRO plans to reattempt the EOS-09 mission with a replacement satellite after completing the analysis.
Looking Ahead
Despite the setback, ISRO’s track record remains strong, with successes like Chandrayaan-1 and the Mars Orbiter Mission. The failure is a reminder of the complexities of space exploration, but ISRO’s resilience and rigorous analysis processes are expected to pave the way for future success. The agency’s commitment to advancing India’s space capabilities, particularly in Earth observation and national security, remains unwavering.
