PSLV’s Second Consecutive Failure

ISRO’s PSLV-C62 mission failed to reach its intended orbit due to a malfunction in the third stage, marking the second consecutive failure of the PSLV after a similar incident in May 2025.

About PSLV C62 Mission

• Multi-Payload Mission: PSLV-C62 was designed to deploy one primary satellite (EOS-N1) along with 18 secondary payloads from Indian startups, universities, and international partners.
• Return After Setback: The mission marks the return of the PSLV programme after the PSLV-C61 failure in May 2025, caused by a technical anomaly in the third stage of the launch vehicle

EOS-N1 (Anvesha) Satellite

• EOS-N1, codenamed Anvesha (meaning “exploration” in Sanskrit), is an advanced Earth observation satellite.
• It is developed by Defence Research and Development Organisation (DRDO) primarily for strategic and defence applications.
• Key Features: 
  • Equipped with hyperspectral imaging sensors that capture data across hundreds of narrow spectral bands (beyond visible light, into infrared and other wavelengths).
  • It also supports civilian applications like agriculture, urban mapping, environmental monitoring, and resource assessment.

Secondary Payloads on PSLV-C62

• International Collaboration: The mission includes Europe’s Kestrel Initial Demonstrator (KID), a small re-entry capsule developed with a Spanish startup, expected to splash down in the South Pacific Ocean.
• Indian Startups and Academia: Payloads include AayulSAT, CGUSAT-1, DA-1, SR-2, Lachit-1, Solaras-S4, and DSAT-1, reflecting ISRO’s support to NewSpace India

About Polar Satellite Launch Vehicle (PSLV)

• Overview: The PSLV is India’s third-generation orbital launch vehicle, primarily designed to deploy satellites into Polar and Sun-Synchronous Orbits, and is globally recognised as ISRO’s most reliable “workhorse” rocket.
  • Due to its unmatched reliability, PSLV has also been used to launch various satellites into Geosynchronous and Geostationary orbits, like satellites from the IRNSS Constellation
• Number of Stages: 4
• Key Stages of PSLV:
  • First Stage (Solid Propellant): The first stage uses a large solid rocket motor (S139) with strap-on boosters, powered by HTPB solid fuel, to lift the rocket off the launch pad and propel it through the densest layers of the atmosphere.
  • Second Stage (Control and Stability Stage): The second stage is powered by the Vikas liquid engine using UDMH and Nitrogen Tetroxide, providing smooth and controlled thrust to maintain stability and guide the rocket along its intended trajectory.
  • Third Stage (High-Speed Booster Stage): The third stage employs a solid motor (S7) using HTPB fuel to deliver a strong acceleration, pushing the vehicle close to orbital velocity before satellite deployment.
  • Fourth Stage (Precision Stage): The fourth stage uses two liquid engines running on MMH and MON, enabling precise orbital insertion and fine adjustments to accurately place satellites into their designated orbits.

What Went Wrong

• Role of the Third Stage: The third stage is responsible for rapid horizontal acceleration, enabling the rocket to maintain a stable sub-orbital trajectory before final orbital insertion.
• Required Velocity: To avoid being pulled down by gravity, the vehicle must achieve speeds of around 26,000–28,000 km per hour during this phase.
• Pressure Drop Issue: In the May 2025 failure, ISRO attributed the anomaly to an unexpected drop in combustion chamber pressure, reducing thrust and acceleration.
• Possible Cause in PSLV-C62: Although the exact cause is still under investigation, the failure is suspected to be similar, potentially involving leakage or manufacturing defects in the solid motor

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Why the Third Stage Is Critical

• Combustion Dynamics: Solid fuel combustion generates high-pressure gas in the chamber, expelled through a nozzle to produce thrust.
• Sensitivity to Defects: Any leakage or pressure drop leads to insufficient thrust, preventing the vehicle from maintaining orbit.
• Previous Findings: The 2025 failure was reportedly linked to a manufacturing defect.

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