Rocket Falters, Dream Doesn’t: PSLV-C61’s Hiccup, ISRO’s Spirit Unshaken
Sriharikota: India’s trusted rocket, PSLV, faced a rare setback during its 101st mission. The PSLV-C61, launched at 9:32 AM IST from Sriharikota, aimed to place the EOS-09 Earth observation satellite into orbit. While the first two stages worked perfectly, the mission faltered when the third stage lost chamber pressure, leading to mission failure. But as history shows, ISRO’s spirit is stronger than any failed ignition.
Understanding PSLV and Its Third Stage
The Polar Satellite Launch Vehicle (PSLV) is India’s space workhorse, with over 60 successful missions. It has four stages, each propelling the satellite higher. The third stage (PS3) runs on solid fuel called HTPB (Hydroxyl-Terminated Polybutadiene).
- HTPB Fuel: A rubber-like substance, it’s packed with chemicals that burn to release powerful gases.
- Chamber Pressure: The force created by burning fuel inside the motor. Like steam in a pressure cooker, it must stay high to push the rocket.
In PSLV-C61, this pressure suddenly dropped, and the third stage couldn’t generate the thrust needed to reach orbit.
What Could Have Gone Wrong?
ISRO hasn’t revealed the exact reason yet, but experts suggest several likely causes:
- Fuel Defect: If HTPB fuel had air bubbles or was packed unevenly, it wouldn’t burn properly—like a faulty Diwali rocket.
- Motor Case Leak: A tiny crack or hole in the rocket’s body could let gases escape—like a leaking tyre losing pressure.
- Thermal Stress: The motor faces extreme heat and cold during flight. Sudden changes can crack the casing—like a hot clay pot cracking when cooled.
- Nozzle Damage: If the nozzle was blocked or deformed, gases couldn’t escape properly—like a jammed exhaust pipe.
- Uneven Burning: The solid fuel must burn evenly. If not, pressure drops—like a gas stove with a weak flame.
- Testing Miss: Every part is tested, but if a small flaw escaped notice, it could fail mid-flight—like a bat breaking from a hidden crack.
Why This Matters, But Doesn’t Break Us
The third stage is critical. It gives the final push for the satellite to reach its orbit. The failure meant EOS-09, meant to help in agriculture, planning, and security, was lost. But setbacks are part of space exploration. ISRO’s track record of bouncing back is unmatched.
PSLV’s Legacy of Success
This was only the third PSLV failure in over three decades:
- 1993 – PSLV-D1: Stage separation and control issues.
- 2017 – PSLV-C39: Heat shield failed to open.
- 2025 – PSLV-C61: Third stage chamber pressure loss.
In 2021, GSLV-F10 failed too, but that involved liquid fuel. PSLV-C61’s issue is unique and will be studied closely.
What’s Next for ISRO?
ISRO is already working to find the root cause. Experts are:
- Reviewing telemetry data from the rocket’s flight.
- Inspecting the fuel composition, motor casing, and nozzle design.
- Rechecking pre-launch tests for overlooked issues.
ISRO’s journey from SLV rockets to Moon and Mars is built on resilience. This is just a pause, not a defeat.
What is HTPB Fuel?
Hydroxyl-Terminated Polybutadiene (HTPB) is the solid fuel used in PSLV’s third stage. It holds other chemicals together like glue and burns steadily, producing 240 kN of thrust. It’s durable, easy to mold, and perfect for high-speed missions.
Final Thought
PSLV-C61’s setback reminds us that space is tough, but India is tougher. From every failed launch, ISRO has returned stronger. This is not an end—it’s a learning curve. Just like a kite that snaps mid-air, our scientists will tie it back and make it soar higher. India’s space dreams are far from over.
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