Date:15/04/2003 URL: http://www.thehindu.com/2003/04/15/stories/2003041504351200.htm

National

INSAT-3A placed in geostationary orbit

By R.K. Radhakrishnan

CHENNAI April. 14 . The latest Indian National Satellite launched from the French Guyanese spaceport Kourou on April 10 will reach its earmarked orbital slot by the end of the week.

In the third and final stages of orbit-raising operation conducted this morning from Master Control Facility (MCF), Hassan, INSAT-3A has been placed in its Geo Stationary Orbit (GSO).

The manoeuvre was completed by firing the 440 Newton Liquid Apogee Motor onboard the satellite for 3 minutes 41 seconds. The satellite has achieved an orbital period of 23 hours and 48 minutes and is continuously visible to the MCF. The Indian Space Research Organisation (ISRO) said that INSAT-3A is now moving towards its geostationary orbital slot with the planned drift rate of 2 degree a day. It is expected to reach its orbital slot of 93.5 degree east Longitude in the next five days.

MCF is satisfied with the performance of the 440 Newton Liquid Apogee Motor (LAM), which was used to conduct INSAT-3A orbit raising manoeuvres. The performance of the motor was crucial to `lifting' the satellite from its Geostationary Transfer Orbit (GTO) (860 km perigee and 36,000 km apogee with an orbital inclination of 2 degree with respect to the equatorial plane) to its present 36,000 km circular orbit with zero degree inclination. The LAM was fired for a total duration of 130 minutes and 23 seconds in three phases on April 11, April 12 and April 14. A total velocity of 1.411 km per second was added by LAM at the Apogee point of the orbit to take the satellite from GTO to GSO.

INSAT-3A had 1,603 kg propellant at the time of its injection into GTO by Ariane-5 launch vehicle on April 10. After orbit raising operations, it has 505 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 designed life of 12 years.

The deployment of the solar array and the antenna is planned for tomorrow. All subsystems on the satellite are working normally.

INSAT 4 series

The ISRO chairman, K. Kasturirangan, and the Arianespace CEO, Jean-Yves Le Gall, have announced the signing of launch contracts for two more payloads, the INSAT-4A and INSAT-4B. With this, in the past 22 years beginning with the launch of the APPLE experimental satellite, the European Space Consortium, Arianespace, would have launched 13 ISRO satellites.

Both INSAT 4A and 4B will weigh around 3200 kg and are dedicated telecom satellites with 12 ku band and 12 C band transponders.

The signature also signals the admission by ISRO that its Geosynchronous Satellite Launch Vehicle would not be in a position to launch the 3000 kg class satellites, despite the fact that the GSLV would have completed its developmental flights and would — by the time the 4 series is launched — — be carrying commercial payloads.