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The Indian Space Research Organisations has had a happy few years. It won plaudits around the world for successfully pulling off an unmanned Mars mission on a budget smaller than that of a Hollywood film, and has also become adept at putting other countries' satellites into space.

On Tuesday, with the launch of the GSLV-D6, ISRO got to put another feather in its cap. This launch vehicle, which took off from Sriharikota, has a cryogenic engine, capable of using cryogenic fuel. This fuel, key to manned spaceflight, is stored at such low temperatures that it gets compressed, allowing for more to be carried in-flight. This in turn increases the launch vehicle’s carrying capacity. GSLV-D6 is India’s third experiment with a cryogenic engine made entirely indigenously. And its payload is equally important: The GSLV-D6 will put GSAT-6, India’s 25th geostationary communication satellite, into orbit around the earth. Geostationary satellites orbit the earth at such a speed that allows them to remain above a single fixed location on the ground. GSAT-6, which carries one of the largest antennae used by the agency, will remain above the eastern part of India. These days, a launch like the GSAT-6's might seem par for the course for ISRO, which has managed to send spacecraft as far as Mars. But it wasn't always this easy.

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The GSAT's predecessors were known as the Indian National Satellite, and they were highly ambitious machines. Civilian satellites launched in the 1980s were modest affairs, performing only one function at a time. INSAT, however, had four and.

The satellite had a package to transmit television content from the capital and Ahmedabad to other cities in India and one for communication services such as telephone, fax and video text. A third had remote sensing capabilities and the fourth a precursor of the satellites that today track cloud cover around the subcontinent.

"Thus, INSAT had the communications capacity of an Intelsat IV (the state of the art in communications satellites when INSAT was designed), a meteorological payload effectively equivalent to the Geostationary Operational Environmental Satellite (GOES)-A (then the most advanced of weather satellites), and a direct-broadcast television system akin to the Applications Technology Satellite (ATS)-6 (once again, the frontier of technology), all wrapped into one compact package. INSAT was a crowded Indian bus shot into space," wrote Raman Srinivasan in a book tracing the history of satellites.

The reasons for this level of complexity were varied, featuring political and strategic concerns, and made life much harder for those developing the satellite. But, in 1983, ISRO conducted its first successful launch, of INSAT-1B and they haven't looked back since.