ISRO's Naughty Boy

It's now twice in a row that India's space agency has got its heavy-lift rocket to behave, the one its scientists call the 'naughty boy'. As ISRO's chairman A S Kiran Kumar put it, Thursday's flawless flight of the Geosynchronous Satellite Launch Vehicle (GSLV) D6 showed that the rocket's first successful flight last year, using a homegrown cryogenic propulsion system, was no fluke.

A heavy-lift vehicle has been the missing piece in ISRO's ambitions for years. The GSLV rocket will help meet India's communication needs by placing bigger satellites in orbit. It would give ISRO a better footing in the global satellite launch services market where its smaller sibling PSLV (Polar Satellite Launch Vehicle) has already built a reputation for low-cost launches. Besides, it will be needed for deep space missions.

Indian space scientists have spent two decades trying to master the cryogenic propulsion stage of a rocket needed to haul a two tonne satellite into high orbits. The technology is complex because liquid hydrogen and oxygen are used as propellant at extremely low temperatures — on the GSLV-D6, this stage kicked in at an altitude of 132 kilometres after the vehicle had used up its first two fuel stages comprising solid and earth-storable liquid propellants. The space agency's first home-built cryogenic stage had failed in 2010.

"This is important because it's almost from scratch that India had to develop this technology," says Prof.B N Raghunandan of the aerospace engineering department at the Indian Institute of Science. He reckons that ISRO should be able to establish the GSLV as a launch vehicle with a couple more tests because the other fuel stages and systems have already been proved. "The question of scaling-up will certainly be what ISRO will be thinking about," he says.

Indeed, ISRO is planning its next GSLV launch in July next year even as its space port in Sriharikota is looking at a tight schedule through the year. "In the years to come we have to double, even triple, the number of satellites to put into orbit. I think now the asking rate is about 10 satellites per year starting from this year," said M Annadurai, director of ISRO Satellite Centre.

Globally, an average of 140 satellites weighing over 50 kilogrammes will be launched every year over the next decade by governments and commercial companies, according to Euroconsult, a consulting firm specialising in satellite communications.

The GSLV-D6, incidentally, carried the communication satellite GSAT-6 which had landed ISRO in trouble four years ago, bringing some of its top scientists under the scanner over a leasing agreement with private firm Devas Multimedia. The UPA government had annulled the deal in 2011 saying satellite, or S-band, spectrum could not be leased for commercial purposes but Devas is claiming damages in an arbitration suit. In March this year, the Central Bureau of Investigation registered a case against some senior scientists alleging loss of Rs 578 crore because of the deal while the Enforcement Directorate has registered a money laundering case on the basis of the FIR.

The GSAT-6 carries a piece of new technology: an antenna that can unfurl into a ring with diameter of 6 metres to provide five spot beams over the Indian mainland for S band communication, which will provide data, video or voice communications for strategic users. The satellite also carries a C-band beam, said ISRO.

"Think of GSAT-6 as a cellphone tower in the sky covering all of India. The question is, are there enough ground terminals, handsets and data cards, capable of using this satellite," asks Prashant Butani, Senior Analyst at consulting firm Northern Sky Research.

However, one of the key demands that the space agency would need to address is the gap in communication transponders such as the Ku band used by the Direct-to-Home (DTH) industry. "The DTH industry is suffering a capacity crunch at this time in terms of available transponders," says Butani. According to a 2014 CAG report, the total number of transponders allocated to the DTH industry, as of July 2013, was 76 of which 57 were from foreign satellite systems and the remaining 19 from the INSAT system.