CHENNAI: Preparations are on for the testing of an indigenous cryogenic stage by mid-August at the Liquid Propulsion Systems Centre (LPSC) at Mahendragiri, in Tirunelveli district, Tamil Nadu, said R.V. Perumal, Director, LPSC.

The LPSC is one of the units of the Indian Space Research Organisation (ISRO). On June 28 the Vikas engine, powered by liquid propellants, was tested at Mahendragiri. The firing lasted 240 seconds. "This is a routine test we keep doing," Mr. Perumal said. Vikas engines are used as strap-on booster motors and in the second stage of the Polar Satellite Launch Vehicle (PSLV). They are also used in the second stage of the Geo-Synchronous Satellite Launch Vehicle (GSLV). "We will also use a Vikas engine for powering the GSLV-Mk III, which is under development now," Mr. Perumal said.

More powerful version

The GSLV-Mk III will be a more powerful version of the present GSLV. The first test on an indigenous cryogenic engine was conducted on February 16, 2000 on the foothills of Mahendragiri at the LPSC. Since then, several tests have been done, including a full-duration one for 1,000 seconds.

Indigenous cryogenic engines have a thrust of 7.5 tonnes. They use 12.6 tonnes of propellants. Launch vehicles need cryogenic engines to put heavier satellites, weighing more than two tonnes, into geo-synchronous transfer orbit at a height of 36,000 km above the earth.

Cryogenic engines use cryogenic propellants: liquid hydrogen at minus 265 degrees centigrade as fuel and liquid oxygen at minus 240 degrees centigrade as oxidiser. Development of these is a highly complex technology because of the very low temperatures involved in the use of propellants.

A cryogenic engine is different from a cryogenic stage. For a cryogenic stage in a launch vehicle includes the engine, tanks for storing the propellants, plumbing, electronics, wiring, control and guidance systems, among other things. The first three GSLV flights from Sriharikota used cryogenic stages from Russia.

A GSLV flight, scheduled to take place from Sriharikota between July 10 and 15, will also use a Russian cryogenic stage. It will put INSAT-4C, a communication satellite, into orbit. INSAT-4C weighs about 2,100 kg. The GSLV flight in 2007 may use an indigenous cryogenic stage.

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