The Indian Space Research Organisation (ISRO) has officially announced the successful completion of two hot tests of the Gaganyaan Service Module Propulsion System (SMPS) at its Propulsion Complex in Mahendragiri on July 3, 2025. These tests mark a significant milestone in India’s ambitious human spaceflight program, Gaganyaan, which aims to send Indian astronauts into space.

Overview of The Hot Tests

The hot tests involved firing the SMPS under controlled conditions to validate its performance, reliability, and safety. The Service Module Propulsion System is a critical component of the Gaganyaan spacecraft, responsible for providing the necessary thrust for orbital maneuvers, attitude control, and de-orbiting operations. The two tests conducted were designed to simulate the rigorous conditions the system will face during an actual mission.

The primary objectives of the hot tests were:

Verification of System Integrity: Ensuring that the propulsion system operates as intended under high-pressure and high-temperature conditions.

Performance Assessment: Measuring thrust levels, fuel consumption, and system response to various commands.

Reliability Checks: Identifying and addressing any potential issues that could compromise mission safety.

ISRO reported that both tests were completed successfully, with the SMPS demonstrating stable combustion, consistent thrust output, and robust structural integrity throughout the duration of the firings. The data collected from these tests will be thoroughly analysed to further refine the system and ensure its readiness for the upcoming uncrewed and crewed missions under the Gaganyaan program.

Importance For the Gaganyaan Mission

The successful hot tests of the SMPS are crucial for the overall progress of the Gaganyaan mission. The Service Module’s propulsion system must function flawlessly to ensure the safety of astronauts and the success of mission-critical manoeuvres. These achievements reaffirm ISRO’s commitment to adhering to the highest standards of engineering and safety in human spaceflight.

Following the successful tests, ISRO will continue with a series of additional qualification and integration tests. The insights gained from the July 3 hot firings will inform further enhancements to the propulsion system and contribute to the final preparations for the Gaganyaan mission’s launch phase.

ISRO’s successful execution of the two hot tests at Mahendragiri represents a major step forward in India’s journey toward its first indigenous human spaceflight, reinforcing the nation’s capabilities in advanced space technology and mission assurance.

ISRO