Key Highlights
- Both 30‑second and 100‑second hot tests of the SMPS were executed successfully.
- All 16 reaction‑control thrusters and 5 liquid apogee engines fired simultaneously in steady‑state and pulsed windows.
- Measured thrust, pressure and temperature data agreed with pre‑flight predictions, underscoring system reliability.
- Design tweaks to the test article replicated real‑flight conditions, sharpening confidence for full‑duration qualification.
Detailed Insights
The Service Module Propulsion System (SMPS) forms the heart of the Gaganyaan orbital module, enabling orbital adjustments, emergency aborts and trajectory corrections that are vital for crew safety. It consists of a single 440 N liquid apogee motor (LAM) array of five units and a 16‑piece reaction‑control system (RCS) capable of 100 N bursts. The engine units operate in both steady‑state and pulsed modes, allowing the module to maneuver in low‑Earth orbit and to react to emergency conditions.
On July 3, 2025, ISRO ran two “hot” tests at Mahendragiri. A 30‑second run verified steady‑state performance of the RCS under nominal thermal loads, while a 100‑second run exercised the integrated operation of all LAMs and RCS thrusters in both firing regimes. The test article was built with flight‑like propellant loads and hardware geometry so that the data gathered would be representative of conditions encountered during a crew‑carrying mission.
All telemetry matched the expected thrust curves and temperature envelopes, indicating that the engine design and control electronics continue to mature with each successive test cycle. With these results, ISRO is paving the way toward a full‑duration qualification test that will certify the propulsion module for the crew flight.
Key Concepts
- SMPS – Service Module Propulsion System; the propulsion branch of the Gaganyaan orbital module.
- RCS – Reaction Control System; a set of small thrusters that adjust attitude and orbit.
- LAM – Liquid Apogee Motor; a high‑thrust engine used for orbit‑raising burns.
- Hot Test – An in‑flight condition test conducted in a pressurized environment.
- Steady‑State vs Pulsed – Two operating modes differing in thrust duration and power consumption.