ISRO tests cryogenic engine for LVM3-M7 mission

ISRO on Thursday said it had successfully conducted the flight acceptance hot testing of the cryogenic engine identified for the seventh operational mission of the LVM3 launch vehicle (LVM3-M7), scheduled for the fourth quarter of 2026. The same test demonstrated the performance of a LOX Tank Pressurisation Module (LTPM) designed for the C32 stage, an upgraded cryogenic upper stage planned for India’s Gaganyaan missions, it said.

The Gaganyaan project aims to demonstrate India’s human spaceflight capability by carrying a 3-member crew to a 400-km orbit for a 3-day mission and safely returning them to Earth, with a landing in Indian sea waters. The test was conducted on Wednesday at the Main Engine and Stage Test Facility (MET) at the ISRO Propulsion Complex (IPRC), Mahendragiri.

LVM3, formerly known as GSLV MkIII, is ISRO’s heaviest rocket and uses the CE20 cryogenic engine to power its upper stage.

“Cryogenic engines for every mission undergo hot testing as part of their acceptance for flight. To conduct hot testing of this upper-stage engine under sea-level conditions, despite its nozzle being designed for high-altitude operations, a Nozzle Protection System (NPS) was developed and previously validated through multiple qualification tests,” ISRO said in a post on its website.

The NPS has reduced the time and effort involved in flight acceptance testing of cryogenic engines by enabling hot testing under sea-level conditions, thereby avoiding the need for testing under simulated high-altitude conditions, it said.

Stating that future LVM3 missions are planned with the C32 stage operating at an uprated thrust level of 22 tonnes to enhance the vehicle’s payload capability, the space agency said the flight acceptance test was conducted at the 22-tonne thrust level.

“Performance of the CE20 engine met all test objectives, confirming satisfactory performance of the engine systems. In this test, the LOX Tank Pressurisation Module (LTPM) meant for the C32 stage for Gaganyaan was also successfully demonstrated. The engine will be refurbished and assembled for the C32 flight stage for the LVM3-M7 mission, which is scheduled during the fourth quarter of 2026,” it added.

The LOX Tank Pressurisation Module (LTPM) is a specialised aerospace subsystem designed to maintain the required pressure inside a liquid oxygen (LOX) propellant tank during flight.