Gaganyaan Mission: ISRO successfully tests engine that will power Gaganyaan mission

By R Anil Kumar

• ISRO successfully tests engine that will power Gaganyaan mission

• Engineers at ISRO ‘s Propulsion Complex in Mahendragiri carried out a landmark demonstration of the CE20 engine in boot-strap start mode under simulated high-altitude, vacuum conditions

• Successful Demonstration of boot-strap mode start of CE20 cryogenic engine

BENGALURU. The Indian Space Research Organisation (ISRO) has achieved a major breakthrough for its human spaceflight programme with the successful testing of a new start-up method for the CE20 cryogenic engine, which will propel the Gaganyaan mission aboard the LVM3 launch vehicle.

On November 7, 2025, engineers at ISRO ’s Propulsion Complex in Mahendragiri carried out a landmark demonstration of the CE20 engine in boot-strap start mode under simulated high-altitude, vacuum conditions.

This marks the first time ISRO has achieved a boot-strap start for a gas-generator cycle cryogenic engine without relying on any auxiliary stored-gas system — a feat that is likely a global first.

The CE20 engine, already flight-proven at thrust levels between 19 and 22 tonnes, typically uses stored gas to ignite and activate its turbopumps. While reliable, that method requires additional hardware and a dedicated gas bottle for every in-flight restart.

Gaganyaan

For future missions requiring multiple orbital manoeuvres or injections, including deep-space exploration and advanced commercial launches, these extra systems add weight and reduce payload capacity, limiting mission flexibility.

The new test changes that. Instead of using stored gas, Isro deployed a multi-element igniter in both the thrust chamber and the gas generator. After the thrust chamber ignited, the gas generator kicked in using only tank-head pressure, allowing the turbopumps to spin up autonomously.

The engine then ramped up smoothly to a stable, steady operating state, proving that boot-strap starting is reliable and repeatable under real mission conditions.

This innovation significantly enhances the LVM3’s capabilities. By eliminating auxiliary start-up systems, the rocket becomes lighter and more efficient, enabling more payload to be carried into orbit. It also allows Isro to execute multiple in-flight restarts with ease, essential for multi-orbit deployments, complex mission profiles, and human spaceflight requirements.

For the Gaganyaan mission, which aims to send Indian astronauts into space aboard an Indian rocket for the first time, the advancement is a timely boost.

With improved restart capability and greater operational flexibility, the CE20 engine’s new boot-strap mode strengthens Isro’s position in both scientific and commercial space sectors, while pushing India closer to its historic first crewed launch.