Sometime in March this year, when the 49-metre-tall Geosynchronous Satellite Launch Vehicle (GSLV), weighing 414 tonne soars into space to introduce the GSat-4 communications satellite into a pre-determined orbit, India will have made a major ‘celestial gain’, for this three-stage space vehicle features for the first time, a homegrown cryogenic engine stage involving the development of complex and challenging technology for handling super cooled and highly volatile liquid oxygen and liquid hydrogen used in this advance propulsion system. A cryogenic engine stage is capable of generating a higher level of thrust compared to earth storable solid and liquid propellants. So far, only the United States, Russia, the European Space Agency (ESA), China and Japan have flown launch vehicles equipped with cryogenic propulsion systems.

The GSLV launch assumes significance as it will help the Indian Space Research Organisation (ISRO) bridge the gaps in the Indian space programme, initiated with the launch of a 9kg sounding rocket from a rocket test facility at Thumba on the outskirts of Thiruvananthpuram. Incidentally, the GSLV flights launched by ISRO so far have used Russian-supplied cryogenic engine stages for their upper stage. The first two stages of GSLV along with the four strap-ons attached to the first stage were derived from India’s highly successful and reliable space workhorse the Polar Satellite Launch Vehicle (PSLV). ISRO undertook the development of the GSLV in 1990 to enable India to launch its Indian National Satellite System (INSAT) series of communications satellites weighing between 2 and 2.5 tonnes and in turn, bring to an end its dependence on the Ariane space vehicle of the European space transportation company, Arianespace, for getting the INSAT satellites off the ground. As rightly pointed out by ISRO, the indigenous cryogenic engine stage will make India self reliant in all aspects of launch vehicle technology.

 

Further, for the Bangalore-based Antrix Corp, the commercial arm of the Indian space programme, the home grown GSLV will mean an opportunity to expand the scope of its satellite launch services built around PSLV. More importantly, GSLV is also likely to be deployed for launching India’s first manned flight, scheduled for 2015-16.

 

From a strategic point of view, the successful development of the cryogenic propulsion stage for GSLV marks ISRO’s success in overcoming ‘technology denial’ by the advanced, spacefaring nations. From its inception, the GSLV project has faced several hurdles, ranging from the US’ high-tech export ban and cost overruns to schedule slippages and Russia’s ambivalence regarding the transfer of cryogenic engine technology.

 

It was with the objective of speeding up the development of the GSLV that ISRO had signed an agreement with the Russian space outfit, Glavkomos, for the supply of a pair of cryogenic engine stages along with the transfer of relevant technology to ISRO before the breakup of the Soviet Union. However, the disintegration of the once mighty communist empire changed the geopolitical landscape with Russia being coerced by the US into abandoning the proposal to transfer cryogenic engine technology to India. The US argument was that this constituted a violation of the so-called Missile Technology Control Regime (MTCR). According to American perception, the cryogenic system is a sensitive technology system with ‘defence potential’. However, most missile systems in operation make use of earth storable solid fuel since the propellant can be loaded in advance to keep the missile in a perpetual state of readiness.

 

The Indo-Russian deal was watered down to provide for the supply of only seven Russian cryogenic stages to India. This is how ISRO came to undertake the development of cryogenic engine technology in the first half of 1990s. The first stage of GSLV carries 129 tonnes of solid fuel with four strap-on boosters, each with a 40 tonne liquid propellant attached to it. The second stage is the liquid propulsion system with a fuel loading of 37.5 tonnes. The upper cryogenic engine stage with 12.5 tonnes of liquid oxygen and liquid hydrogen develops a thrust of 73-kN with a specific impulse of 454 seconds.

 

A high performance version of GSLV, the GSLV-MKIII, now under development, will help India launch a four tonne class satellite into a geostationary transfer orbit. The 629 tonne GSLV-MKIII is a three-stage vehicle with a 110 tonne core liquid propellant stage and a strap-on stage with two solid propellant motors, each with 200 tonnes of propellants attached to it, constituting the first stage. The upper stage is a cryogenic engine stage with a propellant loading of 25 tonnes.

 

The semi-cryogenic engine technology being developed as part of ISRO’s long-term plan to reduce the cost of access to space, will boost the capacity of the GSLV to six tonnes. This implies a three-fold increase in the launch capability of the GSLV.

 

ISRO, which is forging ahead to sustain India’s leadership position in the field of space exploration is also keen on developing a reusable space vehicle. As part of this, a series of technology demonstrator missions have been conceived of and for this purpose, a winged reusable launch vehicle technology demonstrator has been created. This will serve as a flying test bed for evaluating a variety of technologies like hypersonic flight, autonomous landing, powered cruise flight, and hypersonic flight using air breathing propulsion, which will be made use of in the reusable space vehicle.