On May 18, 2025, the Indian Space Research Organisation (ISRO) faced a significant setback with the failure of the PSLV-C61 mission, intended to launch the EOS-09 Earth observation satellite. The mission encountered issues during the third stage of the flight, marking a rare failure for the highly reliable Polar Satellite Launch Vehicle (PSLV).
Overview of the PSLV
A Cornerstone of ISRO’s Success
The PSLV, operational since the 1990s, is a key launch vehicle for ISRO, designed to deploy satellites into various orbits, including Earth observation, navigation, and geostationary missions. With 63 successful launches prior to this incident, the PSLV has earned a reputation for reliability and cost-effectiveness, supporting both domestic and international satellite deployments.
Structure of the PSLV
Engineering for Precision
The PSLV comprises four stages:
- PS1: Solid rocket motors with six strap-on boosters.
- PS2: Liquid rocket engine (Vikas engine).
- PS3: Solid rocket motor for high thrust.
- PS4: Two Earth-storable liquid engines.
This configuration enables the PSLV to achieve the necessary velocity and altitude for precise satellite placement.
| Stage | Propulsion Type | Key Component |
|---|---|---|
| PS1 | Solid | Six strap-on boosters |
| PS2 | Liquid | Vikas engine |
| PS3 | Solid | High-thrust motor |
| PS4 | Liquid | Two Earth-storable engines |
Details of the PSLV-C61 Mission
EOS-09 and Its Objectives
The EOS-09 satellite was designed for a sun-synchronous polar orbit at 597 km altitude. Equipped with a Synthetic Aperture Radar (SAR) payload, it aimed to provide high-resolution imaging for Earth observation, even in adverse weather conditions. The failure in the third stage prevented the satellite from reaching its intended orbit, raising concerns following the recent GSLV failure during ISRO’s 100th mission.
Historical Context of PSLV Failures
Learning from Past Challenges
The PSLV has faced two prior failures:
- 1993: Inaugural flight failed due to onboard software issues, causing a crash into the ocean.
- 2017: IRNSS-1H mission failed when the heat shield did not separate, preventing orbit deployment.
These incidents highlight the inherent complexities of space missions, even for a vehicle as reliable as the PSLV.
Significance of PSLV in India’s Space Program
A Global Launch Leader
The PSLV has been instrumental in establishing India’s space presence. Its cost-effectiveness and versatility have made it a preferred choice for launching satellites for India and foreign nations. The vehicle’s ability to handle diverse payloads has strengthened ISRO’s reputation as a reliable launch provider.
Future Outlook for ISRO
Resilience and Innovation
Despite the setback, ISRO remains committed to advancing its space capabilities. The agency is focused on identifying the cause of the PSLV-C61 failure and enhancing the reliability of future missions. ISRO’s ongoing innovation will continue to drive India’s ambitions in space exploration and technology development.
Key Highlights
- PSLV-C61 mission failed on May 18, 2025, during the third stage.
- Aimed to launch EOS-09 satellite with SAR payload into a 597 km orbit.
- PSLV has a history of 63 successful launches with only two prior failures in 1993 and 2017.
- Comprises four stages: solid and liquid propulsion systems.
- PSLV’s cost-effectiveness and versatility bolster ISRO’s global reputation.
- ISRO to focus on reliability enhancements for future missions.