The engine is a key part of Isro’s Avatar programme—a concept vehicle launch platform that can be reused, unlike the costly, less-efficient ‘expendable’ (single-use) platforms like PSLV. (PTI)

Isro’s Dual Mode Ramjet (DMRJ) engine—this uses both ramjet and scramjet engine technology designed to deliver supersonic and hypersonic speeds—successfully achieved Mach 6 (six times the speed of sound) speeds and put India in an exclusive club of four nations that have developed such capability.

The engine is a key part of Isro’s Avatar programme—a concept vehicle launch platform that can be reused, unlike the costly, less-efficient ‘expendable’ (single-use) platforms like PSLV.

While ‘expendables’ carry fuel and oxidiser, light-weight ramjets and scramjets rely on burning fuel using ambient air for oxidation.

Without the need to carry an oxidiser, ramjets and scramjets create room for higher payloads than expendables can carry—current efficiency in terms of payload-to-lift-off-mass is just 2-4%, with 85% of the lift-off mass being propellant and the oxidiser, in turn constituting 70% of the propellant mass.

Avatar will use ramjets, scramjets and cryogenic engines for launch—with ramjets powering the low-speed thrust after blast-off, scramjets powering the launch at the hypersonic stage and cryogenic engines kicking in at the edge of the Earth’s atmosphere.

This launch platform is also likely to bring down risks by replacing the multiple-stage launch of the expendables with a two-stage one. Avatar, Isro says, will bring down launch costs by half.

Though this is not the first-time India has ventured into hypersonic speed, or scramjet technology for that matter—DRDO, The Indian Express reports, has been working with a Russian agency to develop the second-generation BrahMos missiles that will be capable of flying some 300 kilometre at Mach 7 speeds.

With the successful DMRJ tests, Isro has significantly expanded its low-cost space tech prowess, having mastered a complex design that achieves a sort of sacred triad of budget space transportation: bringing down propellant mass, reducing the launch platform’s size and making it reusable.

It had already demonstrated with the Mars Orbiter Mission how well it can deliver even with a limited budget, but Avatar gives it an edge as a potential low-cost space-transportation service provider to other nations.