The story so far:

On January 12, the Indian Space Research Organisation’s (ISRO) PSLV-C62 mission lifted off from Sriharikota carrying the EOS-N1 satellite along with 15 co-passenger satellites. Within minutes, ISRO said the mission had “encountered an anomaly during end of the PS3 stage”, and that a detailed analysis was initiated.

What was the anomaly?

In a televised briefing after the launch, ISRO chairman V. Narayanan described what mission control was seeing: that performance was “as expected” up to near the end of the rocket’s third stage, called PS3, then that there was increased “disturbance in the vehicle roll rates”, followed by a deviation in the flight path. In other words, towards the end of the third stage, the rocket was spinning uncontrollably, enough for it to not be able to continue on its planned path. As of January 16, ISRO hasn’t published a statement about the root cause of the mishap.

Following the incident, Thailand’s space agency GISTDA, whose THEOS-2A satellite was on board PSLV-C62, said a malfunction late in the third stage caused an attitude-control abnormality and the vehicle deviated from its trajectory, preventing the rocket from deploying the satellites it was carrying. GISTDA also said the rocket and satellites were expected to fall back and burn up over the southern Indian Ocean. The anomaly resembled the events preceding the failure of the PSLV-C61 mission on May 18, 2025.

What happened to PSLV-C61?

ISRO’s PSLV-C61 mission was carrying the EOS-09 satellite. The rocket failed after the first two stages, with the third stage not performing nominally. ISRO noted a drop in chamber pressure in the third-stage motor case during the PS3 operation, after which it said the mission “could not be accomplished”.

Based on what has been reported publicly so far, both the C62 and the C61 missions suffered decisive anomalies on PS3 after a nominal early ascent and neither could deploy their payloads into the designated orbit (with a qualification for the KID payload). In C62, the main symptom was a “roll rate disturbance” late in the PS3 stage operation; in C61, the symptom was a chamber-pressure drop in the PS3 motor casing.

ISRO’s initial communications in both cases also stressed that an anomaly had occurred and that analysis was underway, but it did not publish a detailed list of corrective actions it would have to take. After the C61 mission failed, Dr. Narayanan constituted a Failure Analysis Committee (FAC) to look into the causes of the mishap. The FAC submitted its report to the Prime Minister’s Office in mid-2025.

What does the FAC do?

The FAC is not a standing body of experts within ISRO but instead an entity the ISRO chairman constitutes in the event of a major incident. Its responsibility is to reconstruct the chain of events leading up to the failure using telemetry and subsystem data and in conversation with people involved in that mission. It’s expected to identify the causes, and recommend corrective action before the vehicle is cleared for a ‘return to flight’.

The Committee members include experts within ISRO as well as relevant experts from academia. It has also been known to include former ISRO chairmen. The FAC submits its final report to the Indian government. The ISRO chairman is Secretary to the Department of Space, which functions directly under the PMO.

The aftermath of the GSLV-F10 mission provides an instructive window into the FAC’s efforts. After that mission failed in 2021, here’s an excerpt of what the FAC found: “The FAC concluded that the lower liquid hydrogen tank pressure at the time of cryogenic upper stage engine ignition, caused by the leakage of vent and relief valve resulted in the malfunctioning of the fuel booster turbo pump, leading to mission abort command and subsequent failure of the mission.”

Where is the PSLV-C61 FAC report?

Although the PSLV-C61 FAC submitted its report to the PMO, the PMO hasn’t cleared it for public release yet. Independent experts criticised the decision to withhold it after PSLV-C62 also suffered an anomaly in its third stage. ISRO has also not said whether it has constituted an FAC for the C62 mission, although a short statement on its website says “a detailed analysis has been initiated”. On November 15, 2025, during an unrelated lecture, Vikram Sarabhai Space Centre director A. Rajarajan had attributed the loss of the PSLV-C61 mission to a “slight manufacturing error”.

That said this isn’t the first time details of the FAC’s findings of a mishap have been withheld. Previous instances include the PSLV-C39 mission in 2017. ISRO has also been terse about the issues leading up to the underperformance of the NVS-02 satellite.

Earlier, even when the FAC report hadn’t been released into the public domain, ISRO had issued statements with detailed summaries of the FAC’s findings, for example, after the GSLV-F10 mission in 2021 and the GSLV-F02 mission in 2006. The aftermath of PSLV-C61 is a break from the past in this sense as well, since no such statements have been issued.

What happened to satellites on PSLV-C62?

The mission’s primary payload was EOS-N1, a surveillance satellite from the Defence Research and Development Organisation. The co-passengers comprised payloads involving Thailand, the U.K., Nepal, France, Spain, and Brazil, plus seven satellites from Indian enterprises.

The PSLV has failed four times so far, but PSLV-C62 was the first time it failed while carrying customer satellites provided by Indian and foreign entities. The mission had been facilitated by ISRO’s commercial arm, NewSpace India, Ltd. While the ISRO didn’t say whether the mission had failed after the anomaly on January 12, the statement from Thailand’s GISTDA suggested that the rocket’s remaining stages and the payloads would fall back down towards the earth and burn up.

The KID payload was a reentry demonstrator — a device designed to fall back down from orbit and splash into the southern Pacific Ocean. In a statement released after January 12, Orbital Paradigm, its Spain-based co-developer, said KID had transmitted “off-nominal” data for about three minutes.

GISTDA said its THEOS-2A satellite had been insured. The Indian private sector payloads onboard PSLV-C62 reportedly hadn’t been insured, so the cost of the loss would have been absorbed by the developers of each satellite. The cost of losing EOS-N1 will be borne by India.

Published – January 18, 2026 03:16 am IST

PSLV-C62 will carry EOS-N1 and 15 co-passenger satellites. Photo: YouTube/ISRO Official

The PSLV-C59/PROBA-3 mission takes off from the Satish Dhawan Space Centre in Sriharikota on December 5, 2024.
| Photo Credit: Ragu R

The Indian Space Research Organisation (ISRO) on Thursday (December 5, 2024) announced that it has successfully launched the PSLV-C59 mission with the European Space Agency’s Proba-3 satellites from Sriharikota in Andhra Pradesh. The two satellites onboard PSLV rocket of Proba-3 mission separated successfully, ISRO said.

“Mission Success! The PSLV-C59/PROBA-3 Mission has successfully achieved its launch objectives, deploying ESA’s satellites into their designated orbit with precision,” ISRO said in a post on X.

“PSLV-C59 has successfully soared into the skies, marking the commencement of a global mission led by NSIL, with ISRO’s technical expertise, to deploy ESA’s groundbreaking PROBA-3 satellites,” it said.

The launch was rescheduled to 4:04 pm on Thursday (December 5, 2024) and a revised countdown was set after sorting out an anomaly detected in the propulsion system of one of the satellites on Wednesday (December 4, 2024), minutes before the launch.

Proba-3 (Project for Onboard Anatomy) consists of two satellites in which two spacecraft would fly together as one, maintaining precise formation down to a single millimetre to study the Corona, the Sun’s outer atmosphere. NewSpace India Ltd, the commercial arm of ISRO has bagged the order from the ESA for the launch.

The mission objective is to demonstrate precise formation flying and two spacecraft – ‘Coronagraph’ and ‘Occulter’ would be launched together in a stacked configuration, ISRO said. ISRO had successfully launched the Proba-1 rocket by the European Space Agency in 2001.

(With PTI inputs)