ISRO—The Intermediate Step Is A Matter Of Degrees (Satellite)

[SatNews] Two days after its launch, INSAT-3D, India’s advanced weather satellite, has reached an intermediate orbit, which is much closer to the 36,000 kms high geostationary orbit, its final orbital home, the Indian Space Research Organisation said on Sunday. INSAT-3D was launched by Ariane-5 launch vehicle in the early hours of July 26th into a Geosynchronous Transfer Orbit with a perigee (nearest point to earth) of 250 kms and an apogee (farthest point to earth) of 35,923 kms. The inclination of INSAT-3D’s orbit with respect to the equatorial plane was 3.495 degrees.

Following this, two major orbit raising manoeuvres were performed on INSAT-3D from ISRO’s Master Control Facility (MCF) in Hassan in Karnataka on Saturday and Sunday by firing the satellite’s Liquid Apogee Motor (LAM). In the critical first orbit manoeuvre performed on Saturday, INSAT-3D’s LAM was fired for 65 minutes. As a result, its perigee rose to 15,780 kms while the apogee was at 35,800 kms. In addition, 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 and 57 minutes.

In the second orbit raising maneuver performed on Sunday, the satellite’s LAM was fired for 24 minutes and the perigee further rose to 31,800 kms while the apogee was at 35,795 kms, ISRO said in a statement. The inclination of the satellite’s orbit has further reduced to 0.02 degrees. The satellite’s present orbital period is 22 hours and 15 minutes, which is closer to the 24 hour orbital period of a satellite in the geostationary orbit.