The GSLV project

By N. Gopal Raj

WHETHER IT was the SLV-3 in 1979, the Augmented Satellite Launch Vehicle (ASLV) in 1987 or the Polar Satellite Launch Vehicle (PSLV) six years later, the first launch of each new rocket by the Indian Space Research Organisation (ISRO) has marked a major technological advance. The present Geosynchronous Satellite Launch Vehicle (GSLV), which is scheduled to be launched on March 28, is the exception. Its most important new technology element - the stage with the cryogenic engine - is entirely Russian, the first time that a non- indigenous stage has flown on an Indian launch vehicle.

Moreover, the cost of the GSLV project, taking into account also the cost of indigenously developing the cryogenic technology, has more than doubled. At the same time, instead of the 2,500 kg satellite it was supposed to launch, the present GSLV will be carrying only a 1,540 kg satellite, an unprecedented shortfall of 38 per cent in performance. In subsequent flights, the GSLV with the Russian cryogenic stage is expected to deliver about 1,800 kg into what is called a geostationary transfer orbit (GTO). The GSLV with the equivalent Indian stage, currently scheduled to fly in two to three years, is expected to place about 2,000 kg into orbit.

Contrast this with the wholly indigenous PSLV on which the GSLV is based. The escalation in the PSLV project cost was 33 per cent and the shortfall in performance at the first launch was only 15 per cent. Three flights later, the PSLV's payload had increased to 20 per cent more than the 1,000 kg in sun-synchronous polar orbit which the rocket had been originally designed for. With further improvements, the PSLV's capability is expected to rise to 1,400 kg, a 40 per cent increase over its original specification.

The improvements planned for the PSLV would also give it the capability to put 1,000 kg into GTO. If it were equipped with the GSLV's four liquid strap-ons, the PSLV would probably be able to deliver around 1,400 kg in GTO. The present GSLV, equipped with the Russian cryo, therefore represents a mere 10 per cent increase over that capability, something which can hardly be described as a big jump in performance.

More worrying is the inadequacy of the GSLV. Intended to put 2,500 kg communication satellites into GTO, the GSLV was essentially a launcher designed for the early 1990s. Even if this capability could be achieved, it would still probably be inadequate to meet the requirements of the present decade. To meet competition from fibre-optics, communication satellites have steadily grown bigger, with more onboard processing, improved flexibility and greater power. In the process, the satellites have become heavier. The average weight of communication satellites increased from 1,200 kg in the 1980s to 3,000 kg by the end of the 1990s. The present decade is expected to be dominated by communication satellites of over 4,000 kg.

To meet this challenge, ISRO is now planning to develop the GSLV Mark-III which would be able to carry over 4,000 kg to GTO. Since, the Mark-III is a completely new launch vehicle and not, as has been done with the PSLV, the steady improvement of a proven basic design, it will cost a good deal of money and time to develop. Although ISRO believes that it can have the Mark-III ready in six years, many of its own launch vehicle experts privately say that ten years is more realistic. Ten years corresponds well with ISRO's past experience as well as the experience of Arianespace, the world's most successful commercial launch company. But that also means that the GSLV will be stuck with about 2,000 kg in GTO all through this decade.

This could be the very decade when ISRO faces its greatest challenge in the lucrative communications satellite segment. Already, a large number of satellite transponders in use over India (half of all transponders, according to one unofficial estimate) are said to be on non- ISRO satellites. Greater penetration of the Internet and private sector entry into telecommunications basic services and long-distance traffic are likely to provide major business opportunities in this decade. There are already reports of vast stretches of fibre-optic cables being laid down in India, including by several private companies. It is therefore probable that ISRO will face growing competition from both fibre-optics and other satellite operators. So, although it currently plans a series of 2,000 kg communication satellites to fly on the GSLV, ISRO may be forced by circumstances to build heavier satellites. Such satellites would then have to be launched abroad. By contrast, after the first successful launch of the PSLV, only one remote sensing satellite, the IRS-1C, has had to be launched abroad. The PSLV was rapidly improved and the IRS-1D, identical to its sister satellite, could be launched from Sriharikota two years later.

There is already a surfeit of launchers available on the international market. If ISRO were to continue launching its communication satellites abroad even after the GSLV becomes operational, it could easily raise questions, even within the organisation itself, about the relevance of the GSLV programme.

The present configuration of the GSLV represents what was intended to be the path with the lowest cost and least development time for launching the Insat communication satellites from within the country. The first two stages of the four-stage PSLV were retained for the GSLV. The PSLV's six solid strap-ons were replaced with four liquid ones which used the same engine as the second stage. The top two stages were replaced with a single cryogenic stage. Running on liquid hydrogen and liquid oxgen, a cryogenic engine is a much more efficient system.

So it was clear early on that cryogenic technology was the single most critical element in the development of the GSLV. In December 1983, an internal committee established by ISRO submitted a detailed 15- volume report on developing this technology. If indigenous development had been pursued wholeheartedly right away, India would almost certainly have had its own cryogenic engine by now. Instead, ISRO waivered for the next seven years between developing the technology indigenously and importing it. During this period, the Missile Technology Control Regime (MTCR) had come into being and the United States had modified its laws to enforce the export controls required by the MTCR.

To make matters worse, by the time ISRO signed the deal in January 1991 for getting the cryogenic engine technology from the erstwhile USSR, the Soviet Union was already falling apart and by December that year had ceased to exist. Words of warning from ISRO insiders about the dangers of entering into a contract with an economically and politically weakened Soviet Union for so critical a technology were ignored. In dire economic straits, Russia, which inherited the cryo contract after the break-up of the Soviet Union, was in no position to withstand American embargoes and enticements. In mid-1993, Russia told India that it would not supply the cryogenic technology.

Given that ISRO would now have to develop cryogenic technology on its own, a sensible course would have been to take a fresh look at the GSLV configuration and the cryo engine to be developed. It was quite clear by this time that the existing GSLV configuration would be inadequate in the years to come. The cryo contract with the Russians had been renegotiated and India was to get seven ready-to-fly cryogenic stages from them. So a GSLV with these imported stages could be flown while ISRO developed its own cryogenic stage and, quite probably, a different sort of GSLV as well.

But ISRO's response when Russians refused to supply cryogenic technology was to insist that much of the technology had already been acquired and that an indigenous equivalent could be quickly developed. The private assessment of ISRO's liquid propulsion engineers at the time was that an indigenous cryogenic stage was ten years away. Events have now proved this assessment to be accurate.

Given the official ISRO position, when the Cryogenic Upper Stage project to develop an indigenous cryogenic stage was approved in 1994, its aim was to produce a stage similar to the Russian one. The consequence of this strategy has been that the GSLV will deliver only about 2,000 kg to GTO. If a different cryogenic stage and GSLV configuration had been taken up then, it is quite possible that a far more powerful and relevant GSLV would have become available to ISRO in a couple of years from now.

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