ISRO's CE20 Cryogenic Engine Achieves Milestone with Successful Vacuum Ignition Trial

On February 7, 2025, the Indian Space Research Organisation (ISRO) achieved a significant milestone by successfully conducting a vacuum ignition trial of its indigenous CE20 cryogenic engine. This engine powers the upper stage of the LVM3 launch vehicle and was tested using a multi-element igniter under conditions simulating the vacuum of space. The trial took place at the High Altitude Test Facility within the ISRO Propulsion Complex in Mahendragiri, Tamil Nadu.

Understanding the CE20 Cryogenic Engine

The CE20 engine is a critical component of ISRO's LVM3 launch vehicle, serving as the powerhouse for its cryogenic upper stage. Designed and developed by the Liquid Propulsion Systems Centre (LPSC), this engine operates on a gas generator cycle, utilizing liquid oxygen (LOX) and liquid hydrogen (LH2) as propellants. In its standard configuration, the CE20 engine produces a nominal thrust of 186.36 kN (approximately 19 tonnes) in a vacuum, with a specific impulse of 442 seconds. Recent advancements have enabled the engine to achieve an enhanced thrust of up to 22 tonnes, broadening its application for various missions.

The Complexity of In-Flight Re-Ignition

Restarting a cryogenic engine during flight is a complex endeavor. Traditional methods often rely on stored gas systems to initiate turbopumps. ISRO is exploring an alternative approach known as the bootstrap mode, where both the thrust chamber and gas generator are reignited under tank head conditions. This method aims to simplify the restart process and enhance the engine's reliability for multiple ignitions during a single mission.

Advancements in Multi-Element Ignition Technology

A pivotal aspect of the recent test was the evaluation of the multi-element igniter. Unlike single-point igniters, a multi-element igniter uses several small jets or ignition points to evenly distribute the initial combustion energy. This design ensures a more reliable and efficient ignition process, which is crucial for in-flight restarts. In previous ground tests, ISRO demonstrated vacuum ignition of the CE20 engine without nozzle closure. The latest trial further validated the performance of the multi-element igniter under vacuum conditions, marking a significant step forward in the engine's development.

Implications for Future Missions

The successful vacuum ignition trial of the CE20 engine with a multi-element igniter has several important implications:

• Enhanced Mission Flexibility: The ability to restart the engine in space allows for complex mission profiles, including deploying multiple satellites into different orbits and executing orbital corrections.

• Increased Payload Capacity: The uprated thrust capability of up to 22 tonnes enables the LVM3 launch vehicle to carry heavier payloads, expanding its utility for various missions.

• Support for Human Spaceflight: The CE20 engine has been qualified for the Gaganyaan mission, India's ambitious human spaceflight program. The successful demonstration of in-flight re-ignition capabilities enhances the safety and flexibility required for crewed missions.

ISRO's recent achievements with the CE20 cryogenic engine underscore its commitment to advancing space propulsion technology. The successful vacuum ignition trial not only validates the engine's design and performance but also paves the way for more versatile and ambitious space missions in the future.