The Indian Space Research Organisation (ISRO) has been constantly testing a powerful semicryogenic engine at the ISRO Propulsion Complex (IPRC) in Mahendragiri, Tamil Nadu. This engine is set to make India’s Launch Vehicle Mark-3 (LVM3) rocket much stronger, helping it carry bigger satellites into space.
The LVM3, also called GSLV Mk III, is one of India’s most powerful rockets. It is used to launch satellites for communication, weather monitoring, and even scientific missions. The rocket has three stages that work together to push it into space:
The S200 Solid Boosters (First Stage) are two giant solid-fuel boosters that give the rocket the initial power to lift off from the ground. In the second stage, there is the L110 Liquid Core Stage, which is the liquid-fuelled stage with two Vikas engines that use special fuels (UDMH and N2O4) to keep the rocket moving. Then there is the C25 Cryogenic Upper Stage which is a super-cool stage that uses liquid hydrogen and liquid oxygen to place satellites into their final orbits.
"Currently the LVM3 can carry about 4 tons (4,000 kg) to a high orbit called Geostationary Transfer Orbit (GTO) and up to 8 tons (8,000 kg) to a lower orbit called Low Earth Orbit (LEO). But ISRO wants to make the LVM3 even better by replacing the L110 stage with a new semicryogenic stage called SC120," explained space expert Girish Linganna.
A semicryogenic engine is a special type of rocket engine that uses a mix of refined kerosene (like a super-clean fuel) and liquid oxygen. Unlike the current L110 stage, which uses complex chemicals, or the C25 stage, which needs super-cold liquid hydrogen, the semicryogenic engine is easier to handle and store. This makes it cheaper and more practical. The engine ISRO is building, called the SE2000, is super strong, producing a thrust of 2000 kN—enough to lift very heavy satellites into space.
"The SC120 stage, powered by the SE2000 engine, will replace the L110 stage. This upgrade is expected to boost the LVM3’s GTO payload capacity to 6 tons (6,000 kg) or more. That means India can launch bigger satellites for things like faster internet, better TV signals, or even space exploration," added Linganna.
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Experts say that to make sure the semicryogenic engine works perfectly, ISRO is testing a part of it called the Power Head Test Article (PHTA). The PHTA includes all the engine’s key systems, like fuel pumps, the pre-burner, and control parts, except the thrust chamber (where the fuel burns). These tests began in March 2025 and are checking if the engine starts smoothly and runs safely.
The tests are like rehearsals to ensure the engine is ready for real rocket launches. Each test teaches ISRO’s scientists how to make the engine better and safer.
"Rockets are very complex, and even a tiny mistake can cause a mission to fail. By testing the semicryogenic engine, ISRO is making sure it works perfectly before putting it into the LVM3. The new SC120 stage will make the LVM3 much stronger, allowing it to carry heavier satellites. This is a big deal because with a 6-ton GTO capacity, India can launch advanced satellites for communication, navigation, or scientific research. Also the semicryogenic engine uses kerosene, which is cheaper and easier to handle than other fuels, saving money. At the same India can offer to launch satellites for other countries, earning money and showing off our technology," said Linganna.
Experts point out that a stronger LVM3 could help ISRO send astronauts to space or explore the Moon and Mars.
ISRO will keep testing the semicryogenic engine to make it ready for the LVM3. Once the SC120 stage is complete, it will replace the L110 stage, making the LVM3 one of the world’s top rockets. This will open the door to bigger and bolder space missions for India.
