Rocket Falters, Dream Doesn’t: PSLV-C61’s Hiccup, ISRO’s Spirit Unshaken
On a bright morning at 9:32 AM IST, from the iconic launch pad in Sriharikota, the Indian Space Research Organisation (ISRO) sent off its trusted rocket—the PSLV-C61—on what was supposed to be another success story. The mission aimed to place the EOS-09 Earth observation satellite into orbit, a satellite designed to aid in agriculture, urban planning, and national security. But even rockets, like people, sometimes falter.
The first and second stages of the PSLV-C61 performed flawlessly, lifting the mission with the precision that has defined over 60 previous PSLV launches. However, as the rocket transitioned into its third stage—its final big push to space—something went wrong. A sudden and significant drop in chamber pressure meant that the third stage couldn’t generate enough thrust. The result: the satellite never reached its intended orbit.
A Closer Look: What Is the PSLV and Why the Third Stage Matters?
The Polar Satellite Launch Vehicle (PSLV) is the backbone of India’s space missions. With over six decades of reliability and success, the PSLV has built India’s reputation as a cost-effective and efficient space power. It’s a four-stage rocket, with each stage contributing to propelling the payload higher and faster.
The third stage (PS3) is especially crucial. It runs on solid fuel—specifically, Hydroxyl-Terminated Polybutadiene (HTPB)—and provides the burst needed to transition from Earth’s gravity to space orbit.
Key Components of the Third Stage:
- HTPB Fuel: A rubber-like polymer, it serves as the engine’s energy core. Once ignited, it burns steadily and powerfully.
- Chamber Pressure: This is the internal force generated as the fuel burns. Like steam in a pressure cooker, it must remain consistent to create thrust.
In PSLV-C61’s case, the chamber pressure dropped mid-flight. The rocket, though perfectly aligned and functioning in earlier stages, was left underpowered at a critical moment.
Possible Reasons for the Failure
Though ISRO has yet to release a detailed analysis, aerospace experts propose several plausible causes:
- Fuel Defects: If the HTPB mixture had trapped air bubbles or was unevenly packed, it would burn inconsistently, affecting pressure generation—like a Diwali rocket that fizzles out.
- Motor Case Leak: A tiny breach in the solid rocket casing could allow pressurized gases to escape, reducing thrust—comparable to a slow leak in a tire.
- Thermal Stress Damage: Rockets endure extreme temperature shifts. The stress could lead to microcracks—similar to how heated glass shatters under cold water.
- Nozzle Malfunction: A deformed or blocked nozzle disrupts the smooth exit of gases, leading to low efficiency—just like a car’s muffler jam.
- Uneven Fuel Burning: If the HTPB didn’t burn uniformly, it could cause pressure fluctuations—like an inconsistent flame on a gas burner.
- Missed Flaws During Testing: Despite exhaustive pre-launch tests, a small manufacturing defect might have been overlooked.
Why This Failure Hurts—But Doesn’t Defeat
Losing the EOS-09 satellite is a significant setback. It was a vital asset meant to aid precision agriculture, climate monitoring, and security operations. However, failure is not foreign to space agencies. NASA, Roscosmos, and ESA have all faced mission losses. What defines a space agency is how it bounces back—and ISRO has a history of rising from its setbacks with renewed vigor.
PSLV’s Exceptional Legacy
PSLV-C61 marks only the third failure in the PSLV’s storied history:
- 1993 – PSLV-D1: Stage separation issues during the debut flight.
- 2017 – PSLV-C39: Payload fairing failed to separate, trapping the satellite.
- 2025 – PSLV-C61: Third stage lost chamber pressure, ending the mission prematurely.
Each of these failures brought major lessons. They led to technical upgrades, better simulations, and tighter quality controls. PSLV’s success rate still exceeds 95%, making it one of the most reliable launch vehicles globally.
What Happens Next?
ISRO’s response is already underway. Their engineers and scientists are:
- Analyzing telemetry data from the mission to understand the failure timeline.
- Testing fuel samples, inspecting the motor casing, and examining the nozzle assembly.
- Revisiting pre-launch procedures to find any missed clues.
This isn’t just damage control. It’s how ISRO evolves. From the early SLV-3 failures to the triumphs of Chandrayaan, Mangalyaan, and Aditya-L1, ISRO has shown it doesn’t just launch rockets—it launches determination.
What Makes HTPB Special?
HTPB is not just fuel—it’s a sophisticated blend of science. It acts as both binder and energy source, holding the oxidizers and metals together in a solid mass. When ignited, it burns with high intensity, releasing gas at tremendous velocity. It’s also:
- Easy to mold and store
- Stable at room temperature
- Capable of producing up to 240 kN thrust
But like all engineered materials, it demands perfection in manufacturing and testing.
Read This: Top 10 ISRO Missions that Changed the Face of Space Exploration
Final Thought: When a Rocket Falls, a Dream Rises
The failure of PSLV-C61 is not a defeat; it’s a reminder of the complexity of spaceflight. Every rocket carries not just metal and fuel, but hopes and learning. ISRO’s strength lies not only in its successes but in its unyielding resolve when faced with adversity.
As India watches this mission with a heavy heart, it also looks to the sky with unwavering faith. Just as a kite may snap but be re-tied to fly again, ISRO will regroup, refine, and relaunch. PSLV-C61 may have faltered, but the dream it carried soars on—undaunted and undiminished.
India’s journey to the stars continues—one setback at a time, one success after another.
