ISRO's GSLV-D6 successfully launches communication satellite GSAT-6: All you need to know

The Indian Space Research Organisation (ISRO) successfully launched the Geo-synchronous Satellite Launch Vehicle (GSLV) D6 which carried India’s latest communication satellite GSAT-6. The 29-hour countdown for this launch began at 11.52 am on Wednesday after the Mission Readiness Review (MRR) committee and Launch Authorisation Board (LAB) cleared the starting of the countdown. The launch itself took place at 4.52 pm on Thursday from Satish Dhawan Space Centre at the spaceport of Sriharikota in Andhra Pradesh. After the launch, ISRO scientists at the mission control centre in Sriharikota watched their monitors intently to see the rocket’s progress. The feat is the second one for the ISRO scientists in using the indigenously made cryogenic stage after the 5 January, 2014 launch of GSLV-D5. The earlier one had propelled India into an elite group of countries boasting of the homegrown complex cryogenic engine and stage after twin failures in 2010. ISRO is the sixth space agency in the world after those of US, Russia, Japan, China and France to have joined the indigenous cryogenic regime, which is crucial for launch of heavier satellites weighing more than two tonnes. Describing the successful launch as a “Onam gift”, Mission Director R Umamaheswaran said the ’naughty boy’ (cryogenic stage) has now been transformed into the ‘most adored boy of the ISRO’. “ISRO has offered an Onam gift… a reliable launch vehicle with our own Made in India cryogenic stage… which can launch 2-2.5 tonne class satellites,” he said. “We have demonstrated what happened in January 2014 was no fluke, it was a result of tremendous effort put in by the entire team for the indigenous cryogenic stage… various intricacies of cryogenic have been understood,” a jubilant ISRO Chairman AS Kiran Kumar said. PM Modi congratulated the ISRO team, terming the launch as a “phenomenal accomplishment”.

Another day & another phenomenal accomplishment by our scientists. Congratulations @isro for the successful launch of GSAT-6.

— Narendra Modi (@narendramodi) August 27, 2015

Here are the important points you need to know about the GSAT-6 launch: [caption id=“attachment_2410444” align=“alignnone” width=“825”] Image courtesy: isro.gov.in[/caption] What is GSAT-6? GSAT-6 is the 25th geostationary communication satellite of India built by ISRO and 12th in the GSAT series, according to PTI. GSAT-6 will provide communication through five spot beams in S-band and a national beam in C-band for strategic users, ISRO said. The mission life of the satellite is nine years. The cuboid shaped GSAT-6 has a lift-off mass of 2,117 kg. Of this, propellants weigh 1132 kg and the dry mass of the satellite is 985 kg, ISRO said. It also said that after the satellite’s injection into GTO (Geosynchronous Transfer Orbit) by GSLV-D6, ISRO’s Master Control Facility (MCF) at Hassan will take control of GSAT-6 and perform the initial orbit raising manoeuvres by repeatedly firing the Liquid Apogee Motor (LAM) on board the satellite, finally placing it in the circular Geostationary Orbit. After this, deployment of the antenna and three axis stabilisation of the satellite will be performed. GSAT-6 will be positioned at 83 deg East longitude. [caption id=“attachment_2410446” align=“alignnone” width=“825”] Image courtesy: isro.gov.in[/caption] GSAT-6 has largest antenna made by ISRO so far One of the advanced features of GSAT-6 satellite is its S-Band Unfurlable Antenna of 6 m diameter. This is the largest satellite antenna realised by ISRO. The antenna is utilised for five spot beams over the Indian mainland. The spot beams exploit the frequency reuse scheme to increase frequency spectrum utilisation efficiency. [caption id=“attachment_2410450” align=“alignleft” width=“825”] Image courtesy: isro.gov.in[/caption] Significance of GSLV-D6 According to ISRO website, GSLV-D6 is the ninth flight of India’s GSLV and the fifth developmental flight of GSLV. By putting GSAT-6 into orbit, the GSLV rocket would shed its ‘developmental flight’ tag, reported IANS. Moreover, the Indian space agency would, in all probability, declare its GSLV rocket variant -the GSLV-Mk II - fully operational after it successfully put the GSAT-6 communication satellite into orbit, a senior official of Indian space agency said. “The rocket will be declared fully operation once this mission ends successfully,” K Sivan, Director, Vikram Sarabhai Space Centre (VSSC) told IANS. The GSLV is a three stage/engine rocket and has a total carrying capacity of around 2.2 tonne. The first stage is fired with solid fuel, the second with liquid fuel and the third is the cryogenic engine. The Indian space agency is flying the GSLV rocket with its own cryogenic engine for the second time on Thursday after the successful launch of a similar rocket in January 2014 that put the GSAT-14 into orbit. A cryogenic engine is more efficient as it provides more thrust for every kilogram of propellant burnt. This is the fifth time ISRO is flying a GSLV rocket carrying a satellite weighing over two tonnes. Of the four earlier missions, three failed due to various reasons and one was successful. [caption id=“attachment_2410448” align=“alignnone” width=“825”] Image courtesy: isro.gov.in[/caption] Why is this launch important? Apart from communication provided by GSAT-6 and the importance of GSLV-D6 successfully launching the satellite, this launch is also significant for ISRO because ISRO officials have said that the Indian space programme urgently needs the GSLV for launching its communication satellites because many satellites have been launched by the European Ariane launchers at higher costs, reported The Hindu. India pays around Rs 500 crore as launch fee for sending up a 3.5 tonne communication satellite, according to IANS. The satellite cost is separate. Thus, the GSLV would reduce the cost of launching a satellite. The next GSLV could be launched as early as the first half of 2016, the report quoted Sivan as saying. The report added that when the GSLV is fully achieved, ISRO plans to have two flights of the GSLV in a year. ISRO is also working on the development of a GSLV-Mark III which is twice the capacity of the GSLV-Mark II and will be flown for the first time around December 2016. (With agency inputs)