In the third and final stage of orbit-raising operation conducted on 1st October at 1:38 PM IST from Master Control Facility (MCF), Hassan, INSAT-3E was placed in near Geostationary Orbit (GSO). The manoeuvre was completed by firing the 440 Newton Liquid Apogee Motor on board the satellite for a duration of 3 mn, 6 secs. With this, the satellite has achieved an orbital period of 23 hours and 46 minutes and is continuously visible to MCF, Hassan. INSAT-3E is now moving towards its geostationary orbital slot with the planned drift rate of 2.3° per day. It is expected to reach its orbital slot of 55° East Longitude in the next ten days.
The 440 Newton Liquid Apogee Motor (LAM), which was used to conduct INSAT-3E orbit raising manoeuvres, has performed well. It enabled taking the satellite from its Geosynchronous Transfer Orbit (GTO) of 649 km perigee and 36,000 km apogee with an orbital inclination of 7° with respect to the equatorial plane to its present near GSO orbit with zero degree inclination. The LAM was fired for a total duration of 121 minutes in three phases on September 29, September 30 and 1st October. A total velocity of 1460 m/sec was added by LAM at the Apogee point of the orbit to take the satellite from GTO to GSO.
INSAT-3E had 1592 kg propellant at the time of its injection into GTO by Ariane-5 launch vehicle on September 28. After orbit raising operations, it has 510 kg of propellant remaining that is sufficient to arrest the drift and park it 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.
After the completion of the third apogee motor firing, the Solar Arrays and Antennae of INSAT-3E were deployed by commanding from Master Control Facility, Hassan.
In the first operation, the Solar Array on the south side of the satellite was deployed at 15:01 pm IST. Then, the antenna reflector on the west side of the satellite was deployed at 15:59 pm IST. This was followed by the deployment of the Solar Array on the north side at 17:26 pm and finally the antenna reflector on the east side was deployed at 18:03 pm IST.
The Sun tracking solar array of INSAT-3E 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 stabilization of INSAT-3E is successfully carried out today between 7 a.m. and 9 a.m.. 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. The Momentum Wheels onboard the satellite are switched ON, and stabilized to nominal speed of 4500 revolutions per minute to provide gyroscopic stiffness and provide three axis stabilization.
Currently, the spacecraft is at 38° East longitude, and drifting towards its orbital slot of 55° E, at a rate of 2.3° per day. 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. The satellite INSAT-3E is expected to be ready for service by 1st week of November 2003.
