Ariane 5 launches GSAT-8 from French Guiana

At exactly 02.08 a.m. Indian time on May 21, the 800-tonne Ariane 5 launcher carrying two communications satellites weighing over 9000 kilos in its nose fairing, blasted off into space. India’s GSAT-8, the largest and heaviest satellite built by ISRO and its partners, was one of the two "co-passengers" on the flight. The other, an even heavier satellite weighing 5 tonnes was from Singapore and Taiwan.

Although the launch window was 90 minutes long, the countdown began on the dot at 17.38 local time and on the word "top" from the Jupiter Control Room, the cryogenic main engine was ignited. Just 7.05 seconds later the booster rockets roared into life, each containing 250 tonnes of dry powder that gave a thrust of 13,000 tonnes. As the launcher rose vertically, emitting a deafening roar with a blinding orange-red tail flame, there was palpable tension in the control room. For a full six seconds Ariane 5 climbed vertically then turned East, its flame appearing smaller until it disappeared from view amid the thick cumulus clouds hanging low over the equator.

But all was not over for the team of Indian scientists led by ISRO Chairman Dr. K. Radhakrishnan and Dr. T.K. Alex, Director of the ISRO Satellite Centre in Bangalore. It was only 31 minutes and 17 minutes later when GSAT-8 successfully separated from the final stage at an altitude of 249 kilometres above the equator, that a round of applause broke out.

Minutes later Dr. Radhakrishnan announced that ISRO’s Master Control Facility at Hassan near Bangalore had confirmed the reception of signals from GSAT-8. "They have taken charge of the command and control of GSAT-8 immediately after its injection into the geo-stationary transfer orbit."

GSAT-8:

GSAT-8, India’s advanced communication satellite, is a high power communication satellite being inducted in the INSAT system. Weighing about 3100 Kg at lift-off, GSAT-8 is configured to carry 24 high power transponders in Ku-band and a two-channel GPS Aided Geo Augmented Navigation (GAGAN) payload operating in L1 and L5 bands. The 24 Ku band transponders will augment the capacity in the INSAT system. The GAGAN payload provides the Satellite Based Augmentation System (SBAS), through which the accuracy of the positioning information obtained from the GPS Satellite is improved by a network of ground based receivers and made available to the users in the country through the geostationary satellites.

Mission	Communication
Weight	3093 kg (Mass at Lift – off) 1426 kg (Dry Mass)
Power	Solar array providing 6242 watts three 100 Ah Lithium Ion batteries
Physical Dimensions	2.0 x 1.77 x 3.1m cuboid
Propulsion	440 Newton Liquid Apogee Motors (LAM) with mono Methyl Hydrazine (MMH) as fuel and Mixed oxides of Nitrogen (MON-3) as oxidizer for orbit raising.
Stabilisation	3-axis body stabilised in orbit using Earth Sensors, Sun Sensors, Momentum and Reaction Wheels, Magnetic Torquers and eight 10 Newton and eight 22 Newton bipropellant thrusters
Antennas	Two indigenously developed 2.2 m diameter transmit/receive polarisation sensitive dual grid shaped beam deployable reflectors with offset-fed feeds illumination for Ku-band; 0.6 m C-band and 0.8x0.8 sq m L-band helix antenna for GAGAN
Launch date	May 21, 2011
Launch site	Kourou, French Guiana
Launch vehicle	Ariane-5 VA-202
Orbit	Geosynchronous (55° E)
Mission life	More Than 12 Years