The Indian Space Research Organisation (ISRO) has marked a significant step forward in its ambitious Gaganyaan mission by successfully conducting two hot tests of the Service Module Propulsion System (SMPS) at the ISRO Propulsion Complex in Mahendragiri, Tamil Nadu, on July 3, 2025. These tests are crucial for validating the propulsion system that will power India’s first human spaceflight mission, scheduled for 2027.
The two short-duration hot tests lasted 30 seconds and 100 seconds, respectively. The primary objective was to validate the current configuration of the SMPS test article under conditions that closely simulate actual flight. According to ISRO, the propulsion system performed normally, with all parameters aligning with pre-test predictions.
During the 100-second test, ISRO successfully demonstrated the simultaneous operation of all five Liquid Apogee Motor (LAM) engines and all sixteen Reaction Control System (RCS) thrusters in both steady-state and pulsed modes. This comprehensive test ensured that the propulsion system can handle the complex demands of orbital maneuvers and emergency abort scenarios.
The system comprises five LAM engines, each generating 440 Newtons of thrust, and sixteen RCS thrusters, each producing 100 Newtons. The Liquid Propulsion Systems Centre (LPSC) leads the development of the SMPS, incorporating design improvements based on previous test campaigns.
The successful hot tests represent a major milestone in India’s journey to send astronauts into space. These live demonstrations, using real fuel and hardware, are essential for verifying the propulsion system’s readiness for actual flight. The validation of both individual and combined engine operations gives ISRO the confidence to proceed to a full-duration hot test in the near future.
ISRO Chairman V. Narayanan emphasized the importance of these step-by-step preparations, stating that each test parameter is being meticulously checked to ensure mission success on the first attempt.
