INSAT-3D moves closer to its final orbit

INSAT-3D, India’ s advanced weather satellite, has reached an intermediate orbit which is much closer to the 36,000 km high geostationary orbit, its final orbital home.

INSAT-3D was launched by Ariane-5 launch vehicle in the early hours of July 26, 2013 into a Geosynchronous Transfer Orbit with a perigee (nearest point to earth) of 250 km and an apogee (farthest point to earth) of 35,923 km. The inclination of INSAT-3D s orbit with respect to the equatorial plane was 3.495 deg.

Following this, two major orbit raising manoeuvres were performed on INSAT-3D from ISRO s Master Control Facility (MCF) at Hassan by firing the satellite s Liquid Apogee Motor (LAM).

In the critical first orbit manoeuvre performed on July 27, INSAT-3D s LAM was fired for duration of 1 hour 5 minutes. As a result of this, INSAT-3D s perigee rose to 15,780 km while the apogee was at 35,800 km. Besides, the inclination of the satellite s orbit with respect to the equatorial plane reduced to 0.67 deg and the orbital period (time taken by the satellite to revolve round the earth once) reached 15 hours 57 minutes.

In the second orbit raising manoeuvre performed today, the satellite s LAM was fired for  24 minutes and the perigee further rose to 31,800 km while the apogee was at 35,795 km.  The inclination of the satellite s orbit has further reduced to 0.02 deg. The satellite s present orbital period is 22 hours 15 min, which is closer to the 24 hour orbital period of a satellite in the geostationary orbit.

The third orbit raising manoeuvre of INSAT-3D is scheduled on July 29, 2013 to take it to the near geostationary altitude of about 36,000 km.

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