If it’s successful, ISRO can reduce the cost per kg of payload which is $15,000-$25,000 at present

The Indian Space Research Organisation (ISRO) is looking forward to performing “an experiment” before July-end aboard its RH-560 rocket fitted with a supersonic combustion ramjet (scramjet) engine for demonstrating air-breathing propulsion technology.

At three tonnes, the two-stage RH-560, christened Advanced Technology Vehicle (ATV), is the heaviest sounding rocket built by the ISRO. It will lift off from a launch pad built for sounding rockets at Sriharikota. The Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, has developed the engine.

“The ignition of the scramjet engine in flight and holding the flame steadily for five seconds” — when the air from the atmosphere is being rammed into the engine through an inlet at a supersonic speed of six Mach — “is the objective of the experiment,” said VSSC Director K. Sivan.

If the experiment is successful, it will be a stepping stone for the ISRO to achieve low-cost access to space. It means reducing the cost per kg of payload when a launch vehicle is used to put a satellite into orbit. The cost now is in the range of $15,000-$25,000 for a kg of a satellite. Air-breathing engines will bring down this cost drastically. For, as an ISRO press-release on January 10, 2006, put it: “Air-breathing rocket systems use the atmospheric oxygen from their surroundings and burn it with the stored on-board fuel for producing the forward thrust in contrast to the conventional chemical rocket systems which carry both the oxygen and the fuel onboard.

As a result, the air-breathing systems become much lighter and more efficient, leading to reduced overall costs.” Besides, heavier satellites can be put into orbit. But air-breathing engines can operate only during the atmospheric flight phase.

The entire mission will last 260 seconds.