'A solid motor, once ignited, burns until the propellant is exhausted. It cannot simply stop mid-burn,' said a retired senior ISRO official. 'That is what makes this failure puzzling.'
Venkatachari Jagannathan reports on the latest PSLV failure.
Preliminary assessments suggest that the third stage of the PSLV-C62 rocket, which went off course during its January 12, 2026, launch, did not explode and was structurally intact when it descended, according to multiple informed sources. A former senior Indian Space Research Organisation (ISRO) official, who spoke on condition of anonymity, said engineers are continuing to analyse telemetry and flight data.
"The data from the vehicle is being examined in detail and internal reviews are underway," the source said.
"So far, there is no indication of an explosion in the third stage. The stage appears to have remained intact."
The anomaly occurred after the solid-fuel third stage ignited roughly four minutes after liftoff and subsequently shut down -- an outcome experts describe as highly unusual.
"A solid motor, once ignited, burns until the propellant is exhausted. It cannot simply stop mid-burn," said a retired senior ISRO official. "That is what makes this failure puzzling."
Independent experts observing the live broadcast of the mission said the flight behaviour closely resembled that of PSLV-C61, which failed in May 2025.
"From the trajectory deviation visible on the video feed, the similarity with PSLV-C61 is striking," one rocket expert said, declining to be named.
The PSLV-C61 mission failed on May 18, 2025, while carrying EOS-09, a strategic synthetic aperture radar satellite intended to bolster India's all-weather surveillance capability.
The spacecraft, comparable to EOS-04 launched in 2022, was lost, with the mission valued at approximately ₹850 crore.
ISRO did not make public the findings of the Failure Analysis Committee that investigated the PSLV-C61 failure.
However, sources familiar with the internal deliberations said one key recommendation was to replace the graphite nozzle in the third stage with a carbon-carbon composite nozzle.
The change was aimed at mitigating the risk of "burn-through", a catastrophic condition in which extreme heat from combustion gases breaches the nozzle or motor casing, leading to loss of structural integrity and thrust control.
Carbon-carbon composites offer higher thermal resistance, lower weight, and improved mechanical strength compared to graphite.
According to sources, ISRO incorporated this change in the third stage of PSLV-C62.
From workhorse to question mark
The PSLV has long been regarded as ISRO's most dependable launch vehicle. However, a growing number of failures involving strategically significant missions has raised questions about whether that reputation still holds.
Within ISRO, the Geosynchronous Satellite Launch Vehicle (GSLV) was once informally labelled the "naughty boy" because of its early reliability issues.
Now, some insiders privately wonder whether that moniker is shifting to the PSLV.
The C62 failure
The PSLV-DL variant, designated PSLV-C62, lifted off on Monday morning carrying Anvesha (EOS-N1), a hyperspectral satellite with strategic applications.
Midway through the mission, the vehicle deviated from its planned trajectory and began tumbling after an apparent cut-off during third-stage operation.
ISRO Chairman and Secretary, Department of Space, Dr V Narayanan, confirmed that the anomaly occurred toward the end of the third-stage burn, even as the first two stages performed normally.
"There was a deviation in the vehicle's trajectory toward the end of the third-stage performance," Narayanan said, adding that data from ground stations would be analysed to determine the cause.
Unlike in past failures, however, Narayanan did not take questions from the media following the announcement.
Echoes of an earlier failure
The resemblance to PSLV-C61 has unsettled many within the space community.
During that mission, the PSLV-XL variant veered off course about six minutes after liftoff, shortly after the third stage ignited.
At the time, ISRO acknowledged a drop in chamber pressure during third-stage operation but did not elaborate further.
A former senior official said such a pressure drop could result from a malfunctioning main valve, a redundant valve failure, or another upstream component.
A pattern takes shape
The PSLV-C62 failure marks the third setback in a row involving missions linked to national security objectives.
In January 2025, the NVS-02 navigation satellite was successfully inserted into Geosynchronous Transfer Orbit but later became inoperable when a pyro valve failed to open, blocking oxidiser flow.
Although a faulty electrical connector was cited as a possible cause, ISRO did not release the final findings of the Failure Analysis Committee.
This departure from past transparency has drawn quiet concern within the scientific community.
Stakes beyond reputation
The PSLV is a four-stage launch vehicle that alternates between solid and liquid propulsion systems. The January 12 failure involved the PSLV-DL configuration.
Apart from four failures -- its inaugural mission in 1993, a 2017 launch in which the payload fairing failed to separate, and the two recent third-stage-related mishaps -- the PSLV has enjoyed an otherwise strong success record.
ISRO has historically been meticulous in its approach, even dismantling fully integrated launch vehicles in the past to investigate potential faults.
While recent failures may marginally affect ISRO's commercial launch prospects, the more serious implication lies in the repeated loss of strategically sensitive missions.
Whether these incidents represent isolated technical anomalies or point to deeper systemic issues is a question ISRO will now have to address -- both internally and publicly.
"Once may be an accident, twice a failure," said a retired senior ISRO official. "But when it happens a third time, people begin to ask harder questions."
"There appears to be little clarity on accountability when missions worth hundreds of crores of rupees fail," the official added.
Venkatachari Jagannathan can be reached at venkatacharijagannathan@gmail.com
Feature Presentation: Aslam Hunani/Rediff
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