India took another step towards bolstering its power in satellite technology today with the successful launch of the indigenously built Insat-3C from Kourou in French Guiana early today morning.

Fight 147, carrying the Indian Space Research Organistion's (Isro) 2750 kg Insat-3C, lifted off at 05:17 am (IST). After a last-moment hold-up, the Ariane 4 lifted off from the ELA-2 launch complex and released the 2,750-kg multi-mission spacecraft 22 minutes later. The success was the world's first commercial flight of the new year.

Insat-3C will provide vital telecommunications services for the Indian subcontinent, operating with a multi-mission payload of 30 C-band transponders, 2 S-band transponders and a transponder dedicated to mobile communications.

The satellite has been placed in its intended Geo-synchronous Transfer Orbit, in a 3-axis stabilised mode, with a perigee of 570 km and an apogee of 35,920 km and an inclination of 4 deg. with respect to the equator. The satellite is at present going round the earth with an orbital period of about 10.5 hours. The satellite will finally be positioned at 74° east longitude.

The Insat Master Control Facility (MCF) at Hassan in Karnataka, which is tracking, monitoring and controlling Insat 3C, acquired the telemetry signal from Insat-3C at 5:47 am IST. The initial health checks on the satellite indicate that the performance of the satellite is normal, according to the agency. First operations on the satellite were carried out by issuing commands from the MCF. The outermost panel of the stowed solar array on the south side of the satellite was oriented towards the sun to start generating the electrical power required by the satellite during its transfer orbit phase. Subsequently, the earth viewing face was oriented towards earth and calibration of the gyros on board the satellite has been carried out.

During the initial phase of the operation, MCF will utilise Inmarsat Organisation's ground stations at Beijing (China), Fucino (Italy) and Lake Cowichan (Canada). The satellite's orbit is being precisely determined by continuous ranging from the participating Telemetry Tracking and Command (TTC) stations, the agency says.

In the coming days, orbit raising operations on Insat-3C will be carried out by firing the 440 Newton liquid apogee motor on board in stages till the satellite attains its final geo-stationary orbit, about 36,000 km above the equator. The satellite has about 1.5 tonne of propellant (Mono-Methyl Hydrazine - MMH and Mixed Oxides of Nitrogen - MON-3) for orbit raising operations as well as for station keeping and in-orbit attitude control. The on orbit fuel availability will enable maintaining the satellite for operational services for a period of 12 years.

When the satellite reaches near geo-stationary orbit, deployment of the two solar panels and the two antennas will be carried out and the satellite put in its final 3-axis stabilised mode. The payloads will be subsequently checked out before the commissioning of the satellite.

Insat-3C, carrying Fixed Satellite Services (FSS) transponders, Broadcast Satellite Services (BSS) transponders and Mobile Satellite Services (MSS) transponders is intended to continue the services of Insat-2DT and Insat-2C which are nearing their end of life besides improving and augmenting the Insat system capacity.

Insat-3C is the second satellite of the Insat-3 series; the first satellite, Insat-3B was launched in March 2000. Another three satellites Insat-3A, Insat-3D and Insat-3E will be launched in the coming years, Isro says.

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