GS Paper - 3 (Space Technology)

As part of its preparations for the ambitious India’s first human spaceflight mission (Gaganyaan), the Indian Space Research Organisation (Isro) on 28 August 2021 said it successfully conducted a hot test of the system demonstration model (SDM) of the service module propulsion system.


  1. The first hot test of the SDM of the Gaganyaan Service Module Propulsion System (SMPS) was for duration of 450 seconds at Isro Propulsion Complex (IPRC) in Mahendragiri, Tamil Nadu.
  2. The system performance met the test objectives and there was a close match with the pre-test predictions.
  3. A series of hot tests are planned to simulate various mission conditions as well as off-nominal conditions in the coming months.
  4. The service module is part of the Gaganyaan Orbital module and is located below the crew module and remains connected to it until re-entry.
  5. The service propulsion system consists of a unified bi-propellant system consisting of five 440-N thrust engines and 16 100-N reaction control system (RCS) thrusters with MON-3 and MMH as Oxidizer and Fuel respectively.
  6. The SDM, consisting of five 440-N engines and eight 100-N thrusters, was realised (designed) to qualify the propulsion system performance in ground. A new test facility was established at IPRC, for testing the SDM.