India's ISRO Successfully Tests Its Next-Generation Rocket Engine at 88% Power

India's space agency, the Indian Space Research Organisation (ISRO), has taken a significant step forward in building more powerful rockets. On June 24, ISRO successfully fired the power head — the core rotating machinery that drives the engine — of its new semi-cryogenic engine at a thrust level of 175 tonnes, which is 88% of its full target power of 200 tonnes. This was the eighth in a series of gradually escalating tests, following earlier trials at 47% and 60% thrust, showing that engineers are carefully and systematically pushing the engine toward its full capability.

The engine at the centre of all this is called the SE-2000 (previously known as the SCE-200). It belongs to a class of engines capable of producing 2 MN (meganewtons) of thrust — roughly 200 tonnes-force — making it one of the most powerful liquid rocket engines India has ever developed. It is being built by ISRO's Liquid Propulsion Systems Centre (LPSC), a specialised unit that designs and develops rocket engines using liquid fuels. The test was carried out at the ISRO Propulsion Complex, located in Tamil Nadu.

To understand why this engine matters, it helps to know how rocket engines work. Rockets burn fuel and an oxidiser together to produce hot gases that shoot out and push the rocket forward. The SE-2000 uses liquid oxygen (LOX) as the oxidiser and a purified form of kerosene called Isrosene as the fuel. This combination is described as semi-cryogenic because liquid oxygen must be stored at extremely cold temperatures (hence 'cryogenic'), while the kerosene is stored at normal temperatures. The engine uses a method called an oxidizer-rich staged combustion cycle, which means some of the propellant is burned first to drive the turbopumps — powerful pumps that force fuel and oxidiser into the engine at enormous pressure — before the main combustion happens. This cycle is highly efficient but technically very complex to engineer.

The test that was conducted used something called a Power Head Test Article (PHTA). This is a specially built test version that includes all the major rotating and pumping components of the engine — such as turbopumps and preburners — but leaves out the thrust chamber, which is where the final combustion and thrust generation happen. Testing the power head separately allows engineers to verify that the most mechanically demanding parts of the engine work correctly before assembling the full engine.

The engine is being built to power a new rocket stage called the Semi-Cryogenic Propulsion Stage (SC120). This stage is designed to replace the existing L110 liquid core stage in India's current most powerful rocket, the Launch Vehicle Mark-3 (LVM3). The LVM3 is India's heaviest operational rocket and has already launched large satellite missions, including India's Chandrayaan-3 Moon mission. Swapping in the SC120 stage is expected to meaningfully boost how much cargo the LVM3 can carry — raising its capacity to Geostationary Transfer Orbit (GTO, the path used to place communication satellites in high orbit) from 4 tonnes to 5 tonnes, and to Low Earth Orbit (LEO, the nearer orbit used for Earth observation and broadband satellites) from 8 tonnes to 10 tonnes.

The current version of the LVM3 uses an L110 stage that burns a propellant called UDMH (unsymmetrical dimethylhydrazine) paired with nitrogen tetroxide. These chemicals are toxic and hazardous to handle. In contrast, the SE-2000 runs on liquid oxygen and Isrosene, which are far less toxic and considered environmentally cleaner — an additional advantage beyond just raw performance.

Looking ahead, the next major goal is to conduct a full integrated engine hot test, which means firing the complete assembled engine — power head and thrust chamber together — at full rated thrust. This is targeted to happen by the end of 2026, supported by newly built test facilities. Beyond the LVM3, the SE-2000 engine is also expected to play a role in powering future reusable rockets that ISRO is developing under its Reusable Launch Vehicle (RLV) programme. However, it will not be part of Gaganyaan, India's first crewed spaceflight mission, as that programme has its own timeline and cannot wait for the SE-2000 to be fully qualified.

Right now, India faces a practical problem: when it needs to launch very heavy communication satellites, it often has to hire foreign launch providers because no Indian rocket is powerful enough. This is expensive and means India loses out on commercial launch contracts. The SE-2000 and the upgraded LVM3 are central to solving this problem by giving India the muscle to launch bigger payloads independently — which is why getting this engine right is both a technical and a strategic priority.