ISRO Successfully Ground-Tests a Redesigned PSLV Third Stage After Two Launch Failures
On 12 November 2026, ISRO carried out a successful ground static test of the redesigned third stage of the PSLV (called PS3) at the Static Test Facility of the Satish Dhawan Space Centre, Sriharikota (Andhra Pradesh). In a static test, the rocket motor is fired while firmly fixed to the ground, so engineers can measure how it behaves.
The test follows two PSLV failures in a row, both linked to the third stage: PSLV-C61/EOS-09 (18 May 2025), when the pressure inside the third-stage motor suddenly fell, and PSLV-C62/EOS-N1 (12 January 2026), when the rocket showed an unusual spin (roll disturbance) near the end of the third stage and went off its path.
After the failures, ISRO reviewed the whole PS3 stage: design margins (the safety buffer built into a design), checks on raw materials, assembly steps and quality checks.
Changes made: an improved nozzle design with bigger safety margins, extra (backup) sealing in the mechanical joints, and updated rules for raw-material acceptance, assembly and non-destructive testing (checking parts without damaging them) during integration and transport.
ISRO said the test data is being analysed and more tests are planned before the PSLV flies again.
Polar Satellite Launch Vehicle (PSLV)
The Polar Satellite Launch Vehicle (PSLV) is ISRO's medium-lift rocket, best known for placing satellites into low orbits that pass over the poles. It has four stages that burn one after another, and they alternate between solid and liquid fuel. Because of its long record of success, it earned the name "ISRO's workhorse", and it has flown India's famous missions as well as many foreign satellites.
Both recent PSLV failures happened in the solid third stage (PS3). The successful ground test of a redesigned PS3 is the key step before ISRO can return its workhorse rocket to flight and restore customer confidence.
Solid Rocket Motor: How Solid-Fuel Rocket Stages Work
A solid rocket motor is a rocket stage whose fuel is a solid, rubbery block packed inside a strong tube. When it is lit, the block burns from the inside, produces a huge amount of hot gas, and the gas rushes out of a nozzle at the back. That rush of gas pushes the rocket forward. A simple way to picture it: it works like a very large, very carefully engineered Diwali rocket.
Both recent PSLV failures were traced to the solid third-stage motor, first a drop in chamber pressure and then a loss of roll control. ISRO's redesign targets exactly the classic weak points of a solid motor (the nozzle, the seals and manufacturing quality), and the 12 November 2026 static test is how such a fix is proven before flight.
- Ground static test of the redesigned PSLV third stage (PS3): 12 November 2026, Static Test Facility, Satish Dhawan Space Centre, Sriharikota
- Changes: improved nozzle design with larger margins; redundant (backup) mechanical sealing; tighter raw-material acceptance, assembly and NDT checks
- PSLV-C61/EOS-09 failure: 18 May 2025; fall in PS3 chamber pressure
- PSLV-C62/EOS-N1 failure: 12 January 2026; roll disturbance near end of PS3; 16 satellites lost
- PSLV stages: PS1 solid (S139), PS2 liquid (Vikas), PS3 solid (HTPB), PS4 liquid
- PSLV first flight PSLV-D1 (1993) failed; first success PSLV-D2 (1994)
- Further tests planned before PSLV returns to flight