SRIHARIKOTA, Aug 27: Amid overcast skies and rains, GSLV-D6, powered by the indigenous cryogenic upper stage, lifts off from the SHAR Range at 1652 hrs.
After a 29-hour countdown that started at 1152 hr yesterday, the rocket, carrying 2117 kg advanced communication satellite GSAT-6, lifted off from the Second Launch Pad, with a rumble that shook the earth.
Scientists at the Mission Control Centre, including Indian Space Research Organisation (ISRO) Chairman A S Kiran Kumar, his predecessor Dr K S Radhakrishnan and a galaxy of scientists are watching the course of the flight with bated breath.
The mission is all the more important as it will give a major push to the future GSLV programmes that would ferry satellites weighing two tonnes in the Geosynchronous Transfer Orbit (GTO).
ISRO sources said ”it is essential that we have an operational launch vehicle for our communication satellites that are over two tonnes”
”Today’s success marked a major step forward in that direction”, the sources said. ”Today the GSLV has shed the developmental tag and it has got the operational tag”, the sources added.
The performance of the launch vehicle, especially the cryogenic engine was perfect as the satellite was placed into the Geosynchronous Transfer Orbit (GTO) with a perigee of 170 km from the earth and an apogee of 35,975 km, with an inclination of 19.95 deg.
This was the first GSLV mission for ISRO in 19 months, the last one being the successful GSLV-D5 mission in January last year, which too was powered by India’s own cryogenic stage.
The success of the mission comes in the backdrop of ISRO successfully ground testing the indigenously built High Thrust Cryogenic Rocket Engine for a full duration for 800 seconds on July 20 at the Liquid Propulsions Centre at Mahendragiri in Tamil Nadu.
India today joined five spacefaring nations, — US, Russia, UK, China, Japan and France–in mastering the complex cryogenic stage. As the GSLV is crucial for ambitious future programmes including manned missions, the space agency has been working on the vehicle for decades together using a set of cryogenic engines it obtained from Russia before restrictions were imposed.
Mission Director Uma Maheswaran said the success of the launch proved that GSLV has become operational launch vehicle.
”GSLV demonstrated it as an operational launcher, offering a competition to the workhorse launch vehicle, PSLV”, he added. The cryogenic stage was 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 liquified at -183 deg C and Hydrogen at -253 deg C. These are to be kept in such low temperatures and pumped at high volume, posing additional thermal and structural challenges.
GSLV-D6 was the ninth flight of India’s Geosynchronous Satellite Launch Vehicle (GSLV) and also the fifth developmental flight of GSLV.
This was for the third time the indigenously developed Cryogenic Upper Stage (CUS) was carried on-board a GSLV flight. GSAT-6 will provide S-band communication services in the country. S-band telemetry and C-band transponders enable GSLV-D6 performance monitoring, tracking, range safety/flight safety and Preliminary Orbit Determination (POD).
After reaching GTO, GSAT-6 will use its own propulsion system to reach its final geostationary orbital home and would be stationed at 83 Deg East longitude.
GSAT-6 was the 25th geostationary communication Satellite of India built by ISRO and 12th in the GSAT series. Five of GSAT-6’s predecessors were launched by GSLV during 2001, 2003, 2004, 2007 and 2014 respectively.
After its commissioning, GSAT-6 will now join the group of India’s other operational geostationary satellites. GSAT-6 satellite will provide communications through five spot beams in S-band and a national beam in C-band for strategic uses.
The advanced feature of the cuboid shaped GSAT-6 will be its S-Band unfurlable Antenna of 6 m diameter. This is the largest satellite antenna realised by ISRO and it would be utilised for five spot beams over the Indian main land. Only a few countries possess this technology and India today join them in demonstrating it. The spot beams exploit the frequency reuse scheme to increase frequency spectrum utilisation efficiency. The other advanced feature of the satellite was the 70 v bus, which was flown for the first time in an Indian communication satellite. After the injection into the GTO, ISRO’s Master Control Facility (MCF) at Hassan has taken control of GSAT-6 for performing 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 and the GSAT-6 will be positioned at 83 deg East longitude. (UNI)
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