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INSAT-4A launched successfully

SOARING HIGH: European Space Agency's Ariane - 5 rocket lifting off from Kourou in French Guyana on Thursday morning carrying the INSAT - 4A and Europe's weather satellite MSG-2.

SOARING HIGH: European Space Agency's Ariane - 5 rocket lifting off from Kourou in French Guyana on Thursday morning carrying the INSAT - 4A and Europe's weather satellite MSG-2.  

Special Correspondent

Bangalore: ISRO's latest satellite INSAT-4A was successfully launched early Thursday morning by the European Ariane-5G launch vehicles of Arianespace. The 169th flight of Ariane, with ISRO's 3,080 kg satellite and its `co passenger,' a meteorological satellite (MSG-2 of the European EUMETSAT) lifted off at 4.30 a.m. IST from Kourou in Franch Guyana, ISRO Satellite Centre here said. There are eight other Indian satellites in service now.

With 12 high-power Ku-band transponders INSAT-4A is the first to meet the needs of Direct-to-Home (DTH) television services, apart from carrying 12 C-band transponders to augment the INSAT capacity for communication and TV services. It is also the heaviest launched so far by ISRO.

About 30 minutes after the lift-off, INSAT-4A was placed in its Geosynchronous Transfer Orbit (GTO) and is now orbiting the earth at a distance between 622 km and 36,152 km and inclination of 4.02 degrees from the equator. The orbital period is about 10 hours 46 minutes.

`Normal health'

The Master Control Facility (MCF) at Hassan received the first signals from the satellite at 4.32 a.m. IST. Initial checks indicated `normal health,' ISRO said. The MCF subsequently issued commands to the satellite to make the earth viewing face orient towards the earth. The calibration of the gyros on board the satellite was also carried out.

INSAT-4A is being tracked, monitored and controlled from the MCF. During the initial phase, the MCF will use INMARSAT Organisation's Telemetry, Tracking and Command (TTC) ground stations at Beijing, China; Fucino, Italy and Lake Cowichan, Cabada. The ISRO ground station at Biak in Indonesia is also monitoring the satellite and its orbit precisely determined.

In the coming days, INSAT-4A will be manoeuvred to its final geostationary orbit, about 36,000 km above the equator by firing its 440 Newton Liquid Apogee Motor (LAM). When the satellite reaches its geosyncharonous orbit, deployment of its solar panels and two antennas carried out and the satellite put on its final 3-axis stabilised mode. This will be followed by trim manoeuvres to take it to its designated orbital slot. The payloads will be subsequently checked out before commissioning the satellite. It will be positioned at 83 degree East longitude along with INSAT-2E and INSAT-3B.

INSAT-4A carries the following payloads: 12 ku-band 36 MHz bandwidth transponders employing 140 W TWTAs to provide an EIRP of 52 dBW over the footprint covering Indian main land; 12 C-band 36 MHz bandwidth transponders employing 63 W YWTA to provide an EIRP 39 dBW with expanded radiation patterns encompassing Indian geographical boundary, area beyond India in southeast and northwest regions and some parts of Asia Pacific and Gulf countries.

INSAT-4A will measure 15.16 metre with its solar arrays fully deployed in orbit. The spacecraft propulsion system employs a 440 N Liquid Apogee Motor with 1500 kg of Mixed Oxides of Nitrogen and Mono Methyl Hydrazine to take the satellite to its final orbit. It will be stabilised in orbit using sensors, momentum and reaction wheels, magnetic torquers and right 10 Newton and eight 22 Newton Reaction Control Thrusters. The satellite has two solar arrays together generating 5,500 watt of electrical power backed up by three 70 Ah Nickel Hydrogen Batteries. It has two deployable antennas and one fixed antenna for various transmission and receive functions.

With ISRO Satellite Centre, Bangalore, as the lead centre, INSAT-4A had major contributions from the Space Applications Centre, Ahmedabad, Liquid Propulsion Systems Centre at Valiamala and Bangalore; Vikram Sarabhai Space Centre and ISRO Inertial Systems Unit, Thiruvnananthapuram. Many private and public sector industries also contributed. The MCF will be responsible for the initial phase and in-orbit operation of all geostationary satellites of the ISRO.

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