‘Indian rockets to soon use atmospheric oxygen as fuel’

A Rohini sounding on its way to space. Developments in aerospace technology will enable rockets to use atmospheric oxygen as fuel.

In an attempt to make its rockets lighter and carry heavier satellites, the Indian space agency is planning to flight test by the end of this year its own air-breathing engine that will use atmospheric oxygen as fuel.

Air-breathing engines use atmospheric oxygen and burn it with the stored on-board fuel to generate the onward thrust.

Conventional rockets carry both oxygen and chemical fuel on board.

“We will be doing a series of ground tests of the air breathing engine soon. We are planning an actual launch of a sounding rocket - ATV D02 - powered by such an engine by the end of this year,” an official of Indian Space Research Organisation (ISRO) told IANS on condition of anonymity.

The rocket will fly from Sriharikota, India's rocket port located around 80 km from here.

In March, ISRO flew an advanced technology vehicle D01 (ATV-D01) weighing three tonnes from Sriharikota.

ATV-D01, the heaviest sounding rocket developed by ISRO, carried a passive scramjet (supersonic combustion ramjet) engine combustor module as a test bed for demonstration of air breathing propulsion technology.

A scramjet consists of a tube through which inlet air is compressed by the high speed of the vehicle, a chamber where fuel is combusted, and a nozzle through which the exhaust jet leaves at higher speed than the inlet air.

Jet engines use a compressor to squeeze air into the engine, then spray fuel into the compressed air and ignite it to produce thrust by funnelling it through the back.

The advantage of air breathing engine is that it makes the rocket lighter - as oxygen is not carried - enabling it to carry heavier satellites.

Further, it reduces the cost of launch and will help make ISRO a very cost competitive player in the global satellite launch industry.

However, as air breathing engine systems can operate only during the atmospheric phase of flight, they will have to be adapted along with the conventional chemical rockets.