PSLV-C61 Mission aborted: Understanding what went wrong

Bengaluru: In the cool predawn hours of May 18, 2025, the Polar Satellite Launch Vehicle — ISRO’s celebrated “workhorse”— stood poised on its launch pad at the Satish Dhawan Space Centre, Sriharikota.

On board was EOS-09, an advanced Earth observation satellite destined to monitor our planet from a sun-synchronous polar orbit. This was the PSLV’s 63rd flight — and its 27th in the high-thrust XL configuration.

Expectations ran high, but minutes after liftoff, the mission ground to an unexpected halt.

A remarkable record

Since its first flight in September 1993, the PSLV had earned a reputation for reliability and affordability. It had carried Chandrayaan-1 to the Moon in 2008, sent the Mars Orbiter Mission on its historic voyage in 2013, and in 2023 even set a world record by deploying 104 satellites in a single launch.

Yet in its three-decade history, it had stumbled twice before.

PSLV-D1 (1993): The very first flight ended in the Bay of Bengal. A programming error and a retro-rocket misfire during stage separation robbed the vehicle of attitude control, sending it off course.

PSLV-C39 (2017): Poised to place the IRNSS-1H navigation satellite into transfer orbit, the vehicle failed to jettison its protective heat shield. Trapped inside its fairing, the satellite never achieved the required velocity and the mission was lost.

A third hiccup in the third stage

On May 18, everything proceeded flawlessly through the first two stages. But during the third stage’s solid-propellant burn, telemetry revealed a sudden drop in chamber pressure. As ISRO Chairman V. Narayanan explained on the live webcast, “The third stage motor started perfectly, but during its functioning we observed a fall in motor-case pressure — and the mission could not be accomplished.”

Though precise details await the Failure Analysis Committee’s report, early signs point to a propulsion-system anomaly — perhaps a nozzle or valve misalignment — that interrupted the steady thrust needed to reach orbit.

Turning failures into stepping-stones

In rocket science, even a fraction of a percent in performance deviation can decide success or failure. Each PSLV setback has prompted rigorous self-examination at ISRO: software safeguards were tightened after 1993, and fairing-separation mechanisms were upgraded post-2017. Now, lessons from the PS3 investigation will feed into design refinements — from pressure-sensor redundancies to enhanced stage-separation protocols.

The next chapter

Despite this rare stall, the PSLV’s legacy endures. Its modular design, proven flight history, and cost-effectiveness continue to attract both domestic and international payloads.

Within weeks of the C61 anomaly, ISRO confirmed that the next PSLV mission remains on track, a testament to the agency’s agility and resilience.

In the unforgiving arena of space launch, every misstep is an opportunity for insight. As EOS-09’s story intertwines with two earlier failures, it joins a lineage of missions that have collectively propelled India to the forefront of affordable, dependable rocket launches — and will guide every successful liftoff yet to come.