New Delhi: ISRO experienced a rare setback on Thursday morning after an in-flight failure caused its Polar Satellite Launch Vehicle (PSLV-C61) mission to veer off course during its third-stage burn. The launch was at 5:59 a.m. from the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh. It was delivering the Earth Observation Satellite, EOS-09, but the rocket subsequently lost velocity and could not insert EOS-09 into orbit.
This was ISRO’s 101st PSLV launch mission. The failure is concerning, especially given that EOS-09 was an important all-weather imaging satellite to support India's military and disaster management capabilities.
What happened mid-air?
Judging by ISRO’s preliminary data, the PSLV third stage (PS3) did not perform as expected. The velocity fell sharply at a rate of change from 6 km/s down to 2.45 km/s, which in turn reflects a potential loss of thrust, or at a minimum, deviation in trajectory.
ISRO’s Chair, V Narayanan, admitted to this anomaly when appearing together with ISRO's scientists on an official live stream. Narayanan confirmed that "the rocket did not achieve the intended orbit". Heretofore, this sort of live admission is extremely rare at ISRO, reflecting the additional transparency that ISRO is beginning to develop.
What happens now?
ISRO is now starting a complete investigation, with the failure analysis process already having been started. An official Failure Analysis Committee (FAC) has been set up. This is standard practice for ISRO anytime there is a major anomaly.
Speaking to ETV Bharat, Manish Purohit, former ISRO scientist, explained, “The FAC will look into all telemetry data, test records of the third stage, conduct simulations, and even examine the flex nozzle under similar load conditions. These investigations usually take a few weeks to a month.”
He added that the FAC will also audit guidance software, propulsion systems, and structural integrity based on real-time flight data, and cross-reference it with ground-based tracking and radar inputs.
Learning from failure: ISRO’s track record
This isn’t the first time ISRO has bounced back from a setback. After the PSLV-C1 failure in 1993 due to a software bug and the GSLV-F02 crash in 2006 because of a gas generator malfunction, ISRO overhauled its protocols. Each failure became a stepping stone for major upgrades in testing, quality control, and design validation.
“Even the EOS-03 failure in 2021 due to tank pressurisation issues led to improved systems. ISRO learns fast,” said Purohit.
Why this mission mattered
EOS-09 was intended to be a crucial addition to India’s remote sensing fleet. It would have provided all-weather, day-night imagery for strategic and civilian use, from monitoring floods and landslides to tracking military activity along India’s borders. Its loss is not just technical, but strategic.
What to expect next?
The FAC will submit a detailed report in a few weeks. Based on its recommendations, ISRO is expected to redesign faulty systems, upgrade safety checks, and release a public summary of the findings, just as it did after previous failures. Meanwhile, the Indian space community remains optimistic.
“Setbacks are part of the space game,” said Purohit. “What matters is how fast and how smart you recover.”
With Gaganyaan, Aditya-L1, and Chandrayaan-4 lined up, ISRO is likely to double down on validation tests before the next launch.
Read more: 13 More Rockets Will Be Launched This Year, Says ISRO Chief V Narayanan
