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Communication satellite Insat-3E placed near geostationary orbit news
Our Economy Bureau
03 October 2003

Chennai: Indian Space Research Organisation's (ISRO) latest communication satellite Insat-3E was placed near geostationary orbit (GSO) on 1 October 2003.

In the third and final stage of orbit raising operation the 440 Newton liquid apogee motor was fired from 3 minutes and 6 seconds. The satellite has achieved an orbital period of 23 hours and 46 minutes and is continuously visible to the master control facility at Hassan.

Insat-3E is expected to reach its geostationary orbital slot of 55 degree East Longitude in next 10 days with the planned drift of 2.3 degree per day. Currently, the spacecraft is at 38 degree East longitude.

According to ISRO the liquid apogee motor has performed well, taking the satellite from its geosynchronous transfer orbit (GTO) of 649 km perigee and 36,000 km apogee with an orbital inclination of 7 degree with respect to the equatorial plane to its present near GSO orbit with zero degree inclination. A total velocity of 1460 m/sec was added by the motor at the Apogee point of the orbit to take the satellite from GTO to GSO.

The apogee motor was fired for a total duration of 121 minutes in three phases on 29 September, 30 September and 1 October.

Insat-3E had 1,592-kg propellant at the time of its injection into GTO by Ariane-5 launch vehicle on 28 September. After the firing the apogee motor for three times the satellite has 510 kg of fuel. According to ISRO this is sufficient to arrest the drift and park the satellite at its orbital slot as well as maintain the satellite in its orbit and controlling its orientation during its design life of more than 12 years.

The solar arrays and antennae of Insat-3E were deployed by commanding from master control facility, Hassan. First the solar array on the satellite's south side was deployed. It was followed by the deployment of antenna reflector on the west side and the north side solar array.

Insat-3E's solar array has a total area of 29.6 sq m and it is designed to generate 2.9 kW (BoL) of power in orbit. The satellite has two deployable antennas and one fixed antenna to carry out various transmit-and-receive functions.

The three-axis stabilisation of Insat-3E was also carried out successfully. In this configuration spacecraft will be locked to earth continuously through the optical sensors and will maintain the correct attitude to look at the earth in a stable manner. Insat-3E's Momentum Wheels was also switched on and stabilised to nominal speed of 4,500 revolutions per minute to provide gyroscopic stiffness and provide three-axis stabilisation.

The communication payloads will be switched on after reaching the orbital slot, and in-orbit testing of the payloads will be carried out for a duration of three weeks. Insat-3E is expected to be ready for service by the first week of November 2003.


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Communication satellite Insat-3E placed near geostationary orbit