In a rare setback for the Indian Space Research Organisation (ISRO), its trusted Polar Satellite Launch Vehicle (PSLV-C61) failed during its 101st mission on May 18, 2025, resulting in the loss of the EOS-09 Earth observation satellite.
The launch, which took place at 5:59 AM IST from the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh, encountered an anomaly in the rocket’s third stage, preventing the satellite from reaching its intended Sun Synchronous Polar Orbit (SSPO).
Mission Details and Failure Cause
The PSLV-C61, a 44.5-meter-tall rocket weighing 321 tonnes at liftoff, was carrying the 1,696.24 kg EOS-09 satellite, designed to bolster India’s all-weather surveillance capabilities. Equipped with C-band Synthetic Aperture Radar (SAR), the satellite was intended to provide continuous remote sensing data for applications such as border security, disaster response, and agriculture monitoring, even in adverse weather conditions.
According to ISRO Chairman V. Narayanan, the rocket’s first two stages performed as expected. However, approximately 203 seconds into the flight, the third stage, powered by a solid hydroxyl-terminated polybutadiene (HTPB) motor, experienced a “fall in chamber pressure,” leading to underperformance. This anomaly forced ISRO to terminate the mission, and both the rocket’s fourth stage and the payload were destroyed as per safety protocols.
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A Rare Failure for PSLV
The PSLV, often referred to as ISRO’s “workhorse” rocket, has a remarkable track record, with only three full failures in its 63 launches since 1993. The first failure occurred during its maiden flight in 1993 due to a programming error and retro-rocket malfunction, while the second was in 2017 when a payload fairing failed to separate. This latest incident marks the first PSLV failure since 2017, highlighting the rarity of such events. “The PSLV continues to demonstrate consistent reliability,” ISRO stated, emphasizing their commitment to investigate the failure thoroughly.
Impact on India’s Space Program
The loss of EOS-09 is a temporary setback for India’s ambitious space program, which aims to deploy a 52-satellite surveillance constellation. The satellite was a follow-on to the successful EOS-04 mission launched in 2022 and was equipped with deorbiting fuel to minimize space debris, reflecting ISRO’s focus on sustainable space operations. The mission was also significant as the 27th flight of the PSLV’s XL configuration, designed for heavier payloads, and the second launch from ISRO’s new Payload Integration Facility.
ISRO’s internal failure analysis committee, along with a government-appointed external committee, will now probe the third-stage anomaly to identify the root cause. Chairman Narayanan assured that ISRO would “return after conducting a thorough analysis,” signaling confidence in future missions.
Looking Ahead
Despite this setback, ISRO’s recent achievements, including the successful SpaDeX docking experiment in December 2024 and the 100th launch from Sriharikota in January 2025, underscore India’s growing prowess in space exploration. The agency has planned 10 orbital missions for 2025, including a manned Gaganyaan mission and a privately built PSLV launch by a consortium of HAL and L&T. The failure of PSLV-C61 serves as a reminder of the complexities of space exploration, but ISRO’s resilience and track record suggest a swift recovery.
Stay tuned to The Interview Times for the latest updates on ISRO’s missions and India’s space endeavors.