The Indian Space Research Organisation (ISRO) celebrates a significant milestone in its journey into the cosmos. On July 19, 2023, the Gaganyaan Service Module Propulsion System (SMPS) underwent a successful hot test. This high-stakes operation took place at the ISRO Propulsion Complex (IPRC) situated in Mahendragiri.

This test was truly a testament to human ingenuity, as it involved the use of five liquid apogee motor (LAM) engines, each delivering a thrust of 440 Newton (N). Additionally, sixteen reaction control system (RCS) Thrusters, each exerting a force of 100 N, were also utilised in this impressive feat.

Let's delve a little deeper to understand these components better. The Service Module of Gaganyaan is a carefully regulated propulsion system that works on the principle of bi-propellant-based combustion. Its primary function is to serve the demands of the Orbital Module. This involves the performance of several intricate tasks like orbit injection, circularization, on-orbit control, de-boost manoeuvring, and managing SM-based abort, if such a situation arises, during the ascent phase.

The LAM engines, each generating a thrust of 440 N, are the powerhouses that provide the primary propulsive force that drives the mission's ascent phase. In contrast, the RCS thrusters play a crucial role in making fine adjustments to the spacecraft's attitude, ensuring precision in maintaining the correct orientation in space.

The hot test performed on the System Demonstration Model (SDM) replicated the fluid circuit of the Service Module Propulsion System. It included the propellant tank feed system, helium pressurization system, flight-qualified thrusters, and the various control components that keep the system functioning seamlessly.

The first hot test of the Phase-2 test series symbolised a monumental achievement, showcasing the integrated performance of the Gaganyaan Service Module Propulsion System. This test had a duration of 250 seconds and involved the LAM engines working in continuous mode alongside the RCS thrusters, according to the planned test profile.

It is worth noting that as part of the Phase-1 test series of SM SDM, ISRO had previously carried out five hot tests that together spanned a duration of 2750 seconds. The earlier phase deployed five 440 N LAM engines and eight 100 N RCS thrusters. However, for the Phase-2 test series, the upgraded configuration featured a full set-up of five 440 N LAM engines and sixteen 100 N RCS thrusters.

The mastermind behind the design, development, and realization of the Gaganyaan Service Module Propulsion System is the Liquid Propulsion Systems Centre (LPSC), an integral part of ISRO.

The successful completion of this hot test signifies a huge leap forward for the SMPS, as it has proven its integrated performance in the full configuration, which is indeed a moment of great pride for ISRO and the nation.

The journey is far from over, though. Looking ahead, ISRO has meticulously planned five additional tests to further demonstrate the system's capabilities under both normal and off-nominal mission scenarios. This approach echoes ISRO's dedication to rigorous testing, an unwavering commitment to mission success, and a firm belief in the spirit of exploration, marking a significant milestone in India's journey to space.