C-25 stage with C-20 cryogenic engine in action during the injection phase of the CMS-03 satellite

The LVM3-M5 mission marked a significant milestone for ISRO with the first-ever reignition of the C-25 cryogenic engine during a flight. On November 2, 2025, the LVM3-M5 successfully launched the CMS-03, India's heaviest communication satellite to date, weighing 4410 kg, from the Satish Dhawan Space Centre. The mission was the fifth operational flight of the LVM3 heavy-lift launch vehicle.

Key details of the mission are as follows:

The LVM3-M5 vehicle had a total lift-off mass of 642 tons and a height of 43.5 metres.

The launch sequence began with ignition of two solid S200 strap-on boosters at lift-off, which separated around 131 seconds into the flight at 62.3 km altitude.

The L110 liquid core stage ignited at 106.94 seconds and separated at 304.7 seconds at an altitude of 166.9 km.

The C25 cryogenic upper stage, powered by the indigenous CE-20 engine, was ignited at 307.10 seconds and burned until 950.94 seconds, reaching an inertial velocity of 10.14 km/s.

Importantly, after placing the CMS-03 satellite into the targeted Geosynchronous Transfer Orbit (GTO), the CE-20 cryogenic engine was reignited for the first time in flight. This reignition capability will enable the vehicle to place satellites into multiple orbits in one mission, expanding mission flexibility.

The CMS-03 satellite separated from the vehicle at 965.94 seconds at an altitude of 179.8 km.

The C25 cryogenic stage was loaded with approximately 28.6 tons of liquid hydrogen and liquid oxygen.

ISRO Chairman V Narayanan confirmed the enhanced vehicle performance with a payload capacity increase of about 10%, attributing this partly to the C-25 stage improvements and the cryogenic engine reignition.

The LVM3-M5 mission cemented seven consecutive successes of this launch vehicle configuration.

This mission's successful cryogenic engine restart demonstrated a crucial technological advance for India's space capabilities, ensuring that future launches could deploy satellites more efficiently by accessing multiple orbits from a single launch.​

The timeline of the C25 cryogenic engine reignition sequence during the LVM3-M5 mission on November 2, 2025, is as follows:

T+0 seconds: Lift-off with ignition of S200 solid strap-on boosters.
T+106.94 seconds: L110 liquid core stage ignites.
T+131.14 seconds: Separation of S200 strap-on boosters at altitude of 62.3 km.
T+304.7 seconds: L110 core stage separation at altitude of 166.9 km.
T+307.1 seconds: C25 cryogenic upper stage ignites for the first burn, powered by the CE-20 engine.

The first burn of C25 continues until T+950.94 seconds, achieving an inertial velocity of 10.14 km/s, placing the payload and upper stage near the Geosynchronous Transfer Orbit.

T+965.94 seconds: CMS-03 satellite separation at altitude of 179.8 km.

Post satellite separation, the C25 cryogenic engine (CE-20) was reignited for the first time in-flight, showcasing restart capability.

This reignition thrust allows the cryogenic stage to place satellites into precisely targeted or multiple orbits, increasing mission flexibility—a first for the LVM3 series.

The reignition occurred shortly after satellite separation, within the window following the 950-second point of engine cut-off, as part of the orbital insertion precision and mission enhancement. This capability represents a major technological advance in ISRO's cryogenic propulsion and launch vehicle performance.​

The LVM3-M5 mission uniquely demonstrated ISRO's capability to reignite the CE-20 cryogenic engine (C-25 upper stage) mid-flight—a first for this mission series—and successfully launch the heaviest communication satellite from Indian soil into GTO with enhanced vehicle performance and mission flexibility.

Details: The C25 cryogenic engine reignition on LVM3-M5 happened just after satellite separation around T+965 seconds, following the initial burn from T+307 to T+950 seconds, enabling advanced orbital manoeuvres and marking a major milestone in India's space launch technology.

IDN (With ISRO Inputs)