INDIAN SPACE PROGRAM: A BIG LEAP
Monday, 17th December, 2007
The successful testing of the fully Indian designed and developed cryogenic engine stage on November 15 marks a significant milestone in the quest of the Indian Space Research Organisation (ISRO) to attain self-reliance in the launching of satellites from the Indian soil.
This indigenous cryogenic engine stage will now replace the Russian supplied upper stage of the three-stage GSLV, the most powerful space vehicle built by ISRO.
Moreover, this high performance engine would enable GSLV launch a 2.5-tonne class satellite into a geostationary transfer orbit 36,000 km above the equator where a satellite appears stationary with respect to earth.
On a more practical plane, a fully indigenous GSLV would end
India’s dependence on the European Ariane space vehicle for getting the INSAT series of domestic spacecraft off the ground.
Incidentally, the first two stages of 49-metre tall, 414tonne GSLV are derived from the modules of the four-stage Polar Satellite Launch Vehicle (PSLV) which features alternate liquid and solid fuel stages. The first stage of GSLV is one the largest rocket motors in the world and uses Hydroxyl Terminated Poly-butadiene (HTPB) based propellant. The second stage as well as the four strap-on motor use liquid propellant engine derived from PSLV.
Significantly, GSLV was declared operational after both its developmental test flights conducted in April 2001 and May 2003 were successful. In its first operational flight, GSLV successfully launched
India’s first exclusive satellite for educational services EDUSAT in Sept 2004. And during Sept 2006, a GSLV mission taking off from the Satish Dhawan Space Centre (SDSC) in Sriharikota Island successfully orbited
India’s INSAT-4CR communications spacecraft.
The next GSLV flight featuring a fully Indian cryogenic engine stage would launch G-Sat-4 technology demonstrator satellite. With the full-flight duration test for 720 seconds carried out, Liquid Propulsion Systems Centre (LPSC) of ISRO at Mahendragiri in
Tamil Nadu, decks have been cleared for the integration of this cryogenic engine stage with the GSL V flight vehicle. It may be recalled that a ground test for 480 seconds of the complete cryogenic engine stage was completed in August 2007.
The Indian cryogenic stage is powered by re-generatively cooled engine which works on staged combustion cycle developing a thrust of 69.5-kN in vacuum. In addition to this main engine, the stage incorporates insulated propellant tanks, booster pumps, inter stage structures, fill and drain systems, pressurisation systems, gas bottles, pyro valves and cold gas orientation and stabilisation system. According to ISRO, this successful ground testing of the cryogenic upper stage for the full flight duration has validated the design robustness and performance adequacy for this use in GSLV.
ISRO took up the challenge of developing India’s own cryogenic engine in 1990s after it was forced by the USA to drop its plan to transfer cryogenic engine technology to
India on the ground that it violated the Missile Technology Control Regime. Of course, Russia did agree to supply half a dozen cryogenic engines so that
India would be in a position, to operate the GSLV till its own cryogenic engine gets ready.
As pointed out by ISRO, cryogenic stage is technically a very complex system compared to solid or earth storable propellant stages due to the use of propellants at extremely low temperature and the associated thermal and structural problems.
