SRIHARIKOTA: In what is only its fourth fully successful launch, the eternal problem child of the Indian Space Research Organisation - the GSLV, has managed to ferry the GSAT-6 safely to its intended orbit in textbook precision. In the process, it has relieved the immense pressure on the ISRO to prove that the last successful launch of the GSLV in January 2014 was no fluke - the all important Cryogenic Upper Stage, fully indigenous, works.

The relief, and no small amount of pride, was obvious on the faces of the ISRO team when injection of the GSAT-6 went off without a hitch within seconds of the scheduled time - 17 minutes after liftoff. from the Satish Dhawan Space Centre in Sriharikota.

The reaction was best captured by the Mission Director R Umamaheswaran, who in the middle of a stoic reading of the success of the mission, broke out into a full smile when he said that the "naughty boy" of ISRO had finally become its"adored" child. The Chairman of the space agency A S Kiran Kumar however, was typically succinct in his observation. "Today’s performance of launch vehicle was normal. The intricacies of cryogenic engine has been understood," he said. But this "understanding" of the cryogenic engine is of critical importance to the future of India's space program.

The GSLV’s biggest problem so far has been the Cryogenic Upper Stage – a critically important part of the vehicle and, due to its high complexity and sensitivity, one which ISRO has struggled to develop an indigenous version of. The cryogenic stage is an extremely complex system that only a few among the elite group of countries that have space capabilities possess. Unlike the solid and earth-storable liquid propellant stages, it uses propellants at extremely low temperatures - Oxygen liquifies at -183 deg C and Hydrogen at -253 deg C. These are to be kept in such low temperatures and pumped at high volume, which poses additional thermal and structural challenges.

The first indigenously built CUS failed to perform as designed during its first flight in April 2010, when the Fuel Booster Turbo Pump (FBTP) of the CUS malfunctioned. While the next flight of the GSLV, in December of the same year, was also a failure, the reason was malfunctioning liquid-fueled boosters and the CUS had no part to play before the mission was declared a failure.

The next launch however, in January last year, was the success that ISRO had long waited for. The home built CUS functioned without a hitch and so did all other systems. But while that flight was a mere promise of things to come, today’s successful launch comes very close to cementing that promise into reality.

The potential is staggering. India can now well begin reducing the launching of its heavier satellites from the distant spaceports of the European Space Agency. More excitingly, it effectively opens the ground for manned missions – the ability to ferry large payloads reliably an absolute prerequisite. The CUS, which was scheduled to fire for 720 seconds today, and did, had already been successfully test fired for 800 seconds at the ISRO Propulsion Complex (IPRC) at Mahendragiri in July.

Amid all the focus given to the launch vehicle, the payload it carried - the GSAT-6 satellite, the 25th geostationary communication satellite that the country has built, has lost some attention. The GSAT-6 a 2,117kg communication satellite meant to be used primarily for military purposes, works through five spot beams in the S-band and a national beam in the C-band for strategic users. An important advanced feature is its S-Band Unfurlable Antenna of 6 m diameter - the largest such device realised by ISRO with a lifespan of 9 years.