On August 27, 2015, the Indian Space Research Organisation (ISRO) flagged a major milestone in its history through the successful launch of the GSAT-6, a military communications satellite to be inserted into a geostationery orbit. This was the second successful mission of the geosynchronous satellite launch vehicle D6 (GSLV-D6) since the one launched in January 2014. With the third stage powered by a cryogenic engine made in India, the GSLV-D6 carrying the GSAT-6 lifted off the launch pad at the Satish Dhawan Space Centre in Sriharikota at precisely 1652 hours. 17 minutes into the flight, the GSAT-6 entered the geosynchronous transfer orbit (GTO) soon after which the two solar arrays of the satellite were automatically deployed and the Master Control Facility (MCF) at Hassan in Karnataka took over control of the mission.

Over the next few days, the orbit of the GSAT-6 was raised progressively and on the morning of September 6, 2015, the GSAT-6 was successfully positioned in its final orbital slot of 83 degrees East and is collocated with INSAT 4A, GSAT 12, GAAT 10 and IRNSS1C. The GSAT-6 will now be commissioned into service. The GSAT-6 is the 25th communications satellite and the 12th in the GSAT series that has been produced indigenously by ISRO so far. Congratulating the team of scientists of ISRO on the successful launch of the country’s latest communication satellite, Prime Minister Narendra Modi described it as “Another day and another phenomenal accomplishment by our scientists!”. Success of this mission followed by appreciation by the Prime Minister will certainly help boost confidence levels of the scientific community in ISRO.

The Communication Satellite

Weighing 2,117 kg, the GSAT-6 is equipped with an antenna that is six metres in diameter, one of the largest built so far. This huge antenna that incorporates the latest technology is designed to provide communication link through five spot beams in S-band and a national beam in C-band. The GSAT-6 will be able to facilitate totally secure communications amongst the various establishments and units of India’s strategic forces even with small, hand-held devices whether it is for data, video or voice. This would be somewhat akin to having a cell phone tower in space! The user elements of the strategic forces that are widely dispersed or are deployed in remote locations, will thus remain effectively networked round the clock. This quantum jump in the capability to communicate is an indispensable prerequisite for the strategic forces of India to meet with the challenges of the network-centric warfare environment of the future. As the life expectancy of the GSAT-6 is only nine years extendable to 12, it will have to be replaced at the appropriate time to sustain the capability of uninterrupted communication.

The Launch Vehicle

The GSLV is an expendable satellite launch vehicle developed by ISRO in an effort to enhance the capability to launch satellites weighing from two to five tonnes and place them into a geostationary orbit at 36,000 km from Earth’s surface. The aim was also to reduce dependence on the space agencies of foreign nations for the launch of heavy communications satellites. The GSLV is a 49-metre tall, three-stage vehicle with solid, liquid and cryogenic stages respectively. The first stage has a motor that burns solid fuel, the second is fired with liquid fuel and the third stage has the cryogenic engine. The GSLV has an all-up weight of 425 tonnes on lift off.

The GSLV has had somewhat of a troubled history of development. Its maiden launch on April 18, 2001, was not successful as the GSLV carrying GSAT-1 failed to reach the correct orbit. Thereafter, up to the most recent launch on August 27 this year, the GSLV was launched on eight more missions of which two met with only partial success and three ended in failure as these could not achieve the desired orbit.

Cryogenic Technology

A major challenge confronting ISRO in the saga of the development of the GSLV was to master the technology of cryogenic propulsion. A cryogenic engine is considered to be more efficient as it provides higher level of thrust for every kg of propellant burnt. The third stage which is the last stage of the GSLV, requires a cryogenic engine as it is this stage that provides the high thrust required to generate the velocity needed for the injection of the satellite into the desired orbit. The cryogenic engine generates thrust by combustion of a mixture of hydrogen and oxygen. These two elements are required to be stored at extremely low sub-zero temperatures in the GSLV’s fuel tanks to remain in liquid form. This poses a major technological challenge.

India’s efforts in the early 1990s to acquire the technology from Glavkosmos Space Agency of the then Soviet Union for the indigenous development of the cryogenic engine by India did not succeed. In the face of objections raised by the United States that pointed out violation of the international Missile Technology Control Regime (MTCR), Glavkosmos backed out and cancelled the transfer of technology agreement for the development of cryogenic engine by India. However, for the GSLV project, India was able to purchase a few cryogenic engines from the then Soviet Union to get going. Simultaneously, ISRO embarked on an in-house effort to develop this technology.

The flawless performance by the indigenous cryogenic engine for the second time has sent a clear signal to the world that despite sanctions imposed, Indian scientists had indeed mastered cryogenic technology.

The GSLV will not only help meet the nation’s requirement for more efficient communications, it will provide ISRO the capability to launch missions deep into space

GSLV Operational

Although ISRO’s GSLV programme in the initial stages had been plagued with failures, the scientists were not deterred. Through sheer grit and determination, the scientists grappled successfully with the problems and finally after two decades of effort, in 2014, ISRO successfully launched a GSLV-D5 rocket powered by an indigenous cryogenic engine. With this success, India joined the elite club as the sixth nation in the world to possess cryogenic technology. The other nations in this elite group are the US, Russia, Japan, France and China. The mission of the GSLV on August 27 this year was the second successful launch of the GSLV with the indigenous cryogenic engine and it was the third time that the power plant has been put to the test. This was also the second successful mission of GSLV during the last five years after the two major disasters in the year 2010. Incidentally, this was the first successful GSLV mission in the tenure of A.S. Kiran Kumar, the newly appointed Chairman of ISRO who assumed office on January 12 this year. The GSLV is now in a position to be declared as ‘Fully Operational’.

Handsome Returns

Through the successful development of the cryogenic engine, ISRO has not only scripted a new chapter in its history of involvement of its space technology, but has succeeded in ensuring substantial financial gains for the national economy. ISRO was dependent on the European Space Agency Ariane for the launch of heavy communication satellites for which the nation had to shell out humongous sums, as much as $90 million ( Rs. 600 crore) against the fees charged for the launch. Indigenous capability will reduce the cost by around 66 per cent.

The GSLV will not only help meet the nation’s requirement for better and more efficient communications, it will provide ISRO the capability to launch missions deep into space. Apart from these, the GSLV will provide ISRO fresh commercial opportunities in the global satellite launch market. The space agency has already established a good reputation in this area with its highly reliable Polar Satellite Launch Vehicle (PSLV). What is important at this stage is that ISRO must aim to establish reliability of the GSLV beyond any doubt as has been the case with the PSLV.

The successful launch of the GSAT-6 and the GSLV earning the ‘Operational’ tag, is likely to pave the way for collaboration in space exploration between ISRO and the National Aeronautics and Space Administration (NASA) of the US. As per Kiran Kumar, Chairman of ISRO, a joint project dubbed as NASA-ISRO Synthetic Aperture Radar (NISAR) is being jointly planned. The project involves co-development of a dual frequency synthetic aperture radar that will use advanced imaging capable of providing an unprecedented detailed view of the Earth. The system will be capable of observation and measurement of some of the Earth’s most complex processes, including ecosystem disturbances, ice-sheet collapse and natural hazards such as earthquakes, tsunamis, volcanoes and landslides. Project NISAR is expected to be undertaken in 2020-21.

The Future

The next big challenge before ISRO is to achieve operational status for the GSLV Mk III that will have the capability to launch satellites weighing five tonnes. The GSLV Mk III will be nearly 200 tonnes heavier than the Mk II and will have a more powerful cryogenic engine that has already undergone ground test. Success in this project will enable ISRO to compete in the satellite launch market with the space agencies of the most advanced nations in the world.