The Indian Space Research Organisation (ISRO) on Thursday successfully conducted a ground static test of the modified third stage of its Polar Satellite Launch Vehicle (PSLV) at the Satish Dhawan Space Centre in Sriharikota, marking an important step towards restoring the rocket's operational reliability following two consecutive mission failures.
The test involved the PSLV's third-stage solid motor, known as PS3, which had undergone design modifications and strengthened quality-control procedures after anomalies were detected during the PSLV-C61/EOS-09 and PSLV-C62/EOS-N1 missions.
ISRO said the test was conducted successfully at the Static Test Facility on November 12, following a comprehensive review of the third-stage configuration.
The development is significant for India's space programme, as the PSLV has long served as one of the country's principal launch vehicles for deploying Earth observation, scientific and commercial satellites.
๐๐๐ฌ๐ข๐ ๐ง ๐ฆ๐จ๐๐ข๐๐ข๐๐๐ญ๐ข๐จ๐ง๐ฌ ๐ฏ๐๐ฅ๐ข๐๐๐ญ๐๐
Following the anomalies observed in the two missions, ISRO undertook a detailed examination of the third-stage motor's design margins, raw material acceptance criteria, assembly procedures and quality checks.
The review resulted in modifications aimed at improving the motor's structural integrity and operational reliability.
According to the space agency, essential improvements were introduced in the nozzle configuration to strengthen design margins.
Mechanical interfaces were also reinforced, while redundancy was incorporated into sealing systems to improve reliability during operation.
The agency further revised procedures governing the acceptance of raw materials, component assembly and quality inspections.
These modifications were incorporated into the revised PS3 solid motor configuration that underwent Thursday's successful ground test.
๐๐ญ๐ซ๐ข๐๐ญ๐๐ซ ๐ช๐ฎ๐๐ฅ๐ข๐ญ๐ฒ ๐๐ก๐๐๐ค๐ฌ
ISRO said the improvements extended beyond the motor's physical design to include changes in manufacturing, integration and transportation procedures.
Updated non-destructive testing methods were introduced at different stages of integration and transportation to identify potential defects without damaging the components.
The agency also verified the adequacy of the revised design margins and strengthened the mechanical interfaces.
The revised procedures are intended to reduce the possibility of defects affecting the motor's performance during flight.
The successful static firing provided an opportunity to assess the modified configuration under controlled ground conditions before its use in a future launch.
๐๐๐ซ๐ฅ๐ข๐๐ซ ๐ฆ๐ข๐ฌ๐ฌ๐ข๐จ๐ง๐ฌ ๐๐๐ข๐ฅ๐๐
The latest test followed setbacks involving the PSLV-C61 and PSLV-C62 missions, both of which experienced anomalies associated with the third stage.
The PSLV-C61 mission, launched on May 18, 2025, was intended to place the EOS-09 Earth observation satellite into orbit.
Although the vehicle performed normally during its first two stages, an anomaly developed during the operation of the third-stage solid motor, preventing the mission from achieving its objective.
ISRO subsequently constituted a national-level committee comprising experts from academia and industry to investigate the failure and recommend corrective measures.
The agency had also conducted successful static tests of a modified third-stage motor in October and November 2025.
However, another third-stage anomaly during the PSLV-C62/EOS-N1 mission in January 2026 prompted further examination of the rocket's configuration and operational procedures.
The successive setbacks increased the importance of validating the revised third-stage motor before resuming regular PSLV launches.
๐ ๐ฎ๐ซ๐ญ๐ก๐๐ซ ๐ญ๐๐ฌ๐ญ๐ฌ ๐ฉ๐ฅ๐๐ง๐ง๐๐
ISRO said the newly configured PS3 solid motor had been successfully realised and tested following the implementation of the design and procedural changes.
The agency will now undertake a detailed analysis and review of the test data to assess the motor's performance and the effectiveness of the modifications.
Further tests are planned based on the findings of these reviews.
The successful ground test does not, by itself, constitute clearance for the rocket's return to flight, as additional validation and technical assessments remain necessary.
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The PSLV is a four-stage launch vehicle that uses alternating solid and liquid propulsion systems.
Its third stage employs a solid-propellant motor that provides thrust after the separation of the second stage, making its performance essential for achieving the required flight trajectory.
Over several decades, the rocket has played a central role in India's satellite launch programme and has also carried spacecraft for international customers.
It has supported major Indian space missions, including Chandrayaan-1 and the Mars Orbiter Mission.
The latest successful test represents progress in ISRO's efforts to address the technical issues affecting the launch vehicle and restore confidence in its performance.
The agency's next steps will depend on the detailed evaluation of Thursday's test results and the outcome of additional planned trials.