ISRO’s Semi-Cryogenic Milestone: Powering India’s Heavy-Lift Ambitions

The Indian Space Research Organisation (ISRO) has achieved a significant breakthrough with the successful long-duration hot test of its indigenous semi-cryogenic engine. Conducted at the ISRO Propulsion Complex (IPRC) in Mahendragiri, this test marks a pivotal shift in India’s launch vehicle capabilities. The engine, which operates on a Liquid Oxygen (LOX) and refined kerosene (Isrosene) propellant combination, is designed to power the booster stages of future heavy-lift rockets. Unlike traditional cryogenic engines that use liquid hydrogen as fuel, semi-cryogenic engines are more compact, carry higher energy density, and are easier to store at room temperature. This technological leap is expected to increase the payload capacity of India’s heaviest launcher, the LVM3, from its current 4 tonnes to approximately 6 tonnes for Geosynchronous Transfer Orbit (GTO). This enhancement is vital for launching heavier communication satellites and complex interplanetary probes without relying on expensive foreign launch services.