ISRO’s PSLV-C61 Mission Fails to Deploy EOS-09 Satellite

On May 18, 2025, the Indian Space Research Organisation (ISRO) launched its 101st mission—PSLV-C61—from the Satish Dhawan Space Centre in Sriharikota. This mission marked the 63rd flight of the Polar Satellite Launch Vehicle (PSLV), which has been the backbone of India’s space exploration program for over two decades. The PSLV series is known for its reliability and versatility in deploying satellites into various orbits.

The primary payload for this mission was the EOS-09 satellite, designed as a remote sensing Earth observation satellite. This satellite was intended to enhance ISRO’s capabilities in monitoring various natural and environmental parameters, supporting sectors such as agriculture, forestry, water resource management, and disaster relief.

Satellite Purpose

EOS-09 was equipped with advanced sensors to capture detailed images and data related to soil moisture levels, forest cover, crop health, and atmospheric conditions. The satellite’s data would have been invaluable for early warning systems, helping farmers plan better, forest officials track deforestation, and disaster management authorities respond promptly to natural calamities like floods and droughts.

Technical Failure During Launch

Cause of Failure

Unfortunately, during the launch sequence, the third stage of the PSLV rocket experienced a significant drop in chamber pressure. Chamber pressure is a critical parameter within the rocket engine that ensures optimal combustion and thrust. Any sudden decrease in this pressure can cause a severe loss of propulsion power.

In this case, the drop in chamber pressure occurred unexpectedly, which led to the third stage failing to provide the necessary thrust to place the EOS-09 satellite into its designated orbit. Without achieving the correct velocity and altitude, the satellite could not be deployed as planned, leading to the mission’s failure.

Impact on the Mission

The failure means that the EOS-09 satellite either fell short of its intended orbit or did not reach orbit at all, rendering it ineffective for its mission objectives. This technical setback affects ISRO’s Earth observation capabilities and delays the benefits the satellite was supposed to provide to various sectors dependent on its data.

Importance and Impact of EOS-09 Satellite

Applications of EOS-09

The EOS-09 satellite was designed to play a critical role in multiple areas of Earth monitoring. For agriculture, it would have enabled precise tracking of crop conditions, soil moisture, and drought-prone areas, helping optimize irrigation and increase yields. For forestry, the satellite’s imagery would help detect illegal logging, forest fires, and changes in forest density.

In disaster management, EOS-09 was expected to be a vital tool for early detection and assessment of floods, cyclones, and other natural calamities. This satellite’s data would have enhanced India’s preparedness and response capabilities, potentially saving lives and reducing damage.

Consequences of Failure

The failure of this mission is a considerable setback. The absence of the EOS-09 satellite means that current monitoring programs relying on satellite data may experience gaps. This could affect the accuracy of weather predictions, agricultural advisories, and disaster response planning in the short term.

Moreover, the delay in enhancing India’s remote sensing infrastructure may slow progress in environmental protection efforts and scientific research that depend heavily on consistent satellite data.

ISRO’s Response and Future Plans

Investigation Launched

Immediately after the failure, ISRO constituted a Failure Analysis Committee comprising leading scientists and engineers. This team is responsible for thoroughly investigating the cause of the pressure drop in the chamber during the third stage of the PSLV.

The committee is analyzing telemetry data, reviewing the design and performance of the propulsion system, and evaluating all pre-launch checks and ground operations to understand what went wrong. The insights gained will be crucial to implementing design or procedural changes that can prevent similar failures in future missions.

Commitment to Future Missions

Even with this challenge, ISRO is still committed to pursuing its ambitious space program.The agency has reaffirmed plans to maintain a robust launch schedule, targeting approximately one mission every month throughout 2025. These upcoming missions include communication satellites, navigation satellites, scientific payloads, and additional Earth observation satellites.

ISRO’s resilience and commitment to learning from failures have been key to its success as a world-class space agency. The PSLV-C61 failure serves as a reminder of the complexities and risks involved in space exploration, but also underscores the importance of rigorous testing, continuous improvement, and innovation.