Despite having been around for 12 years, and being planned for over two decades, ISRO's GSLV program is still to be considered fledgling.

A press release was put out by the Indian Space Research Organisation (ISRO) shortly after the GSLV-D5 launch from Sriharikota was called off. It read:

GSLV D5 Launch Called Off
Press Release, August 19, 2013

The Launch of the GSLV D5 scheduled for 16:50 hrs today (August 19, 2013) is called off, as a leak is observed in the UH25 fuel system of the liquid second stage during the pre-launch pressurisation phase on the vehicle just two hours before the scheduled lift off.

The propellants are being drained from the Cryogenic Stage, Liquid Second Stage and the four liquid Strap-ons of GSLV D5. The vehicle will be moved back to the Vehicle Assembly Building for further actions.

The revised launch date will be announced after a detailed assessment.

One of India’s two categories of launch vehicles, the GSLV hasn’t seen much success although it has been in development for more than two decades now. There are a lot of problems, many of which I don’t think are in ISRO’s hands. After all, this is the organisation whose PSLV program has been very successful.

In fact, to be fair, the PSLV program has seen 20-30 successful flights, and has had time to stabilise and become reliable.

The Indian GSLV – the Geosynchronous Satellite Launch Vehicle – program saw its first flight in 2001. Ever since, there have been seven flights (6 Mk I, 1 Mk II), with only two successes and one ‘partial’ success (all Mk I). The last four failures have been consecutive; the last two happened in 2010, in April – the first flight of the Mk II variant – and December.

Both are likely to have dealt a moral blow to an organisation aspiring toward interplanetary exploration.

Features and failures

The GSLVs were designed to be able to launch payloads almost twice as heavy as the PSLVs (Polar Satellite Launch Vehicles) can manage – about 1 tonne – into the same orbit, the intermediary Geostationary Transfer Orbit (GTO). From the GTO, a satellite is deployed into its final orbit by deploying its boosters.

Development began in the 1990s, whilst a fledgling PSLV program was underway, so that India could become self-reliant, no longer having to depend on the European Space Agency’s (ESA) Ariane program.

The thinking was that if by 2005 or 2010 the GSLV was well-tested, then ISRO could plan “serious” interplanetary missions. However, the vehicles didn’t fly. The thorn in the crown has been the third propelling stage of the rocket: the cryogenic upper stage (CUS).

The PSLV has four stages that use solid and liquid fuel alternately. The first stage employs a solid propellant with the technology based on the US Nike-Apache engine. The second stage is a liquid engine called the Vikas, whose tech. is based on the French Vulcain engine developed for the Ariane 5.

The GSLV, on the other hand, has three stages: solid, liquid and cryogenic, in that order. As with the PSLV, the first two stages are variants of the Nike-Apache and the Vulcain, respectively. The third stage, CUS, has been indigenously developed.


The Ariane (L) and the GSLV Mk-III (mock-up) are very similar in design, too. Photo: Special arrangement

Russian consignment

After the Pokhran II nuclear tests in 1998, India was denied a consignment of Russian cryogenic engines to bolster our GSLV program by a bent-on-sanctions USA, which also refused to let the Russians sell the engines to us. As a result, India had only seven such engines on the basis of which the CUS program was initiated. Engines that came after were built at the Liquid Propulsion Systems Centre, Tamil Nadu.

Rather difficult to master, the cryogenic technology could also have been hampered by administrative roadblocks as India’s space program became two-pronged: one aided by the PSLV and the other by the GSLV, with focus divided between the two.

Because the GSLV is capable of carrying payloads weighing 2-2.5 tonnes, it is looked at to serve more sophisticated purposes. For instance, the D5 launch’s payload is the GSAT-14 communication satellite, a replacement for the extant GSAT-3/EDUSAT, weighing 1,982 kg. Neither GSAT-3 nor GSAT-14 would’ve been independently possible without the GSLV.

Even though 2001 seems a long way off in the past now, the technology and the promise of self-reliance at hand make the GSLV program seem deserving of continuing tolerance, even if the roster now reads “8 launches, 2 successes, 1 partial success”. It was good that the chaps at ISRO detected the fuel leak before the launch, or the consequences would have been disastrous. Good luck to them and their efforts.

(Many thanks to Pradeep Mohandas for valuable inputs.)