A giant of a rocket

THE Indian Space Research Organisation is all fired up about GSLV Mark III, its heaviest, tallest and most powerful rocket yet. The 42.4-metre-tall rocket will have a lift-off weight of 630 tonnes and can put a four-tonne satellite into the geo-synchronous transfer orbit (GTO) or a 10-tonne satellite into a low-earth orbit. In comparison, the GSLV flight of May 8, belonging to the first generation of GSLVs, put a 1.8-tonne satellite in the GTO. The GSLV Mark II can put 2.2- to 2.4-tonne satellites into the GTO. The GSLV Mark III project will cost Rs.2,500 crores, including the money to be spent on building the facilities to develop the vehicle. The Union government has approved the project and the three-stage rocket will lift off in 2008. Project Director S. Ramakrishnan's room at the Vikram Sarabhai Space Centre (VSSC) in Thiruvananthapuram, the lead-centre for launch vehicle building, is full of posters on the vehicle, with slogans highlighting the importance of self-reliance in launch vehicle technology. "As a project, we should have slogans. We have to motivate people," he said.

GSLV Mark III is not derived from the Polar Satellite Launch Vehicle (PSLV) or the present-day GSLV. "Although it is called Mark III, it is a totally new vehicle," asserted Ramakrishnan. Its upper stage will be powered by a cryogenic engine developed at the Liquid Propulsion Systems Centre (LPSC) at Mahendragiri in Tamil Nadu and codenamed C-25. It will have 25 tonnes of propellants - liquid hydrogen and liquid oxygen - which will develop a thrust of 20 tonnes. "The C-25 is a totally new animal. We have to develop it from scratch, starting from the drawing board."

Besides the cryogenic stage, GSLV Mark III has a core stage of two engines powered by 110 tonnes of liquid propellants and two huge strap-on motors strung around the core. The four-stage PSLV has four strap-on booster motors powered by solid propellants. The two three-stage GSLV Mark I rockets, launched in 2001 and 2003, had four strap-on booster motors powered by liquid propellants.

Each strap-on motor of the Mark III will be 3.4 metres in diameter and they will be 25 metres tall. VSSC Director Madhavan Nair assessed the project thus: "The challenge here is that we have to develop a huge booster with 200 tonnes of solid propellants, and a cryogenic stage with 25 tonnes of propellants. These are the two new major elements to be developed."

The development work on Mark III began in October 2002. New facilities will be established at Sriharikota and Mahendragiri to develop the solid boosters, the core liquid stage and the cryogenic stage. A massive plant will come up at Sriharikota to produce solid propellants for Mark III. This will be in addition to the existing Solid Propellant Booster Plant (SPROB) facility at SHAR, one of the biggest plants of its kind in the world. The private and public sector industries taking part in the project too have to augment their facilities for the realisation of Mark III hardware.

ISRO will establish and commission its new facilities for the project in two years. The first hardware will start rolling out in the second half of 2005, and static and structural tests will begin in 2006. ISRO is aiming the first launch of GSLV Mark III towards the end of 2007 or the first half of 2008. "This is really ambitious," said Ramakrishnan. "We had earlier taken eight to ten years to develop a new vehicle. We have, however, gained experience from the development of the SLV-3 and the PSLV."