Tim Furniss/LONDON

The Indian Space Research Organisation (ISRO) will enter the geostationary launcher club with the first flight of the Geostationary Satellite Launch Vehicle (GSLV) next month. It will be carrying the 1,500kg (1,100lb) Indian satellite, G-SAT 1.

The 49m- (160ft) tall GSLV has been in development for several years and its maiden flight is more than three years later than planned.

The booster comprises elements of the operational Polar Satellite Launch Vehicle (PSLV) and, for initial flights, a Russian-built cryogenic upper stage engine. It will be launched from the PSLV pad at Sriharikota, but a customised GSLV pad is under development.

A second test flight is planned about "12 months after the first test", before the vehicle is declared operational, says ISRO.

The GSLV will be capable of launching payloads of 2,500kg into geostationary transfer orbit, including the Insat 3-D satellite which is set to fly on the third GSLV, says ISRO.

Other Insat 3 series craft are scheduled for Arianespace launches as they are heavier. Insat 3D "will only carry meteorological payloads rather than communications payloads or a mix of the two types", says ISRO.

The first GSLV flight, designated D-1, will carry the lighterG-SAT 1; the second test will carry G-SAT 2. The G-SATs are communications technology satellites "demonstrating digital audio and C-band transponder applications".

The GSLV will also be able to carry 5,000kg payloads into 400km orbit, with each launch costing about $400 million.

The booster comprises two strap-on stages powered by the Vikas nitrogen tetroxide-hydrazine engine used on the PSLV's second stage, with a burn time of 158s. The core booster is based on the PSLV solid propellant first stage, which fires for 274s.

The second stage is a single Vikas engine-powered stage with a 150s burn time, while stage three is powered by the restartable Russian KVD 1M cryogenic liquid oxygen/liquid hydrogen engine used on some Russian Proton boosters, with a total burn time of 800s.

Six further KVD 1 engines will be available for use on the GSLV while India continues to develop its indigenous cryogenic engine in a programme that has been thwarted by technical difficulties.

A test firing last February "was aborted 15s into the burn by a technical problem" that has not yet been resolved, ISRO says. "We still have a long way to go," says ISRO, and it is "likely that all the Russian engines will be used" beforethe introduction of the Indian cryogenic engine.

Source: Flight International