Behind the January 5 triumph of the GSLV-D5 with an indigenous cryogenic stage are some massive facilities that ISRO has built at Sriharikota in Andhra Pradesh and Mahendragiri in Tamil Nadu.
The Satish Dhawan Space Centre (SDSC) at Sriharikota features the spaceport with its two launch pads; propellant filling centres near the first and second launch pads; a bulk storage facility for liquid propellants; and a world-class Mission Control Centre.
The bulk storage facility can house 400 tonnes of liquid propellants of unsymmetrical dimethyl hydrazine and dinitrogen tetroxide, which are highly toxic. “The tanks should be absolutely leak-free,” said M.Y.S. Prasad, Director, SCDC. “There are so many pumps, heat exchangers; flow meters; temperature, pressure and flow sensors; safety relief valves, water drenching systems to quench a fire, and so on.”
The two propellant-filling centres are situated 10 km away from the launch pads and filling is done remotely with the help of optical links, computer networks and remotely controlled valves. While the mass of the liquid propellants loaded into the launch vehicle is measured by the mass flow meter, in the case of cryogenic propellants—liquid oxygen and liquid hydrogen—the mass is measured by their temperature, pressure and other parameters. Yet, about 10.85 tonnes of liquid oxygen should be filled into the GSLV’s cryogenic stage with an accuracy of 70 kg, and 1,900 kg of liquid hydrogen should be pumped in with an accuracy of 12 kg, said Prasad. “Besides, we have to condition the storage tanks, circuits, tubes and valves by cooling them to –252° C so that there is no gas formation,” he added.
The sophisticated Mission Control Centre , inaugurated in January 2012, features more than 50 computers. It coordinates and conducts the launch operations during the countdown phase and until the injection of the satellite into orbit.
At Mahendragiri, near Nagercoil in the foothills of the Western Ghats, is the Liquid Propulsion Systems Centre, where the liquid stages (PSLVs) and the cryogenic stages are built. Also in Mahendragiri is the High Altitude Test (HAT) facility . It was set up for the GSLV-Mk III rocket—currently under development—but was modified to test the cryogenic engine of the GSLV-D5 and the subsequent GSLV-Mk II flights. “We modified the storage facilities, ejectors, support systems, etc. This took one year. It was challenging work. We worked day and night,” said M.C. Dathan, Director, LPSC. Vacuum conditions, simulating the space environment, have been created in the HAT for igniting the cryogenic engine. Dathan added that a Main Engine Test facility and a facility to ensure that the turbo-pump received clean fuel, without any contamination, had also been set up at Mahendragiri.