METSAT Nearing Its Space Home

India's exclusive meteorological satellite, METSAT, which was launched by the Polar Satellite Launch Vehicle (PSLV) on September 12, 2002, has been successfully placed in a near geo-synchronous orbit with a perigee of 34,500 km and apogee of 35,676 km. The orbit raising operations were carried out yesterday (September 15, 2002) by firing the Liquid Apogee Motor (LAM) on board the satellite for a short duration of 31 seconds starting at 10:10 am. In this orbit, the satellite, which is now located at 37 degree East longitude is moving slowly towards its allocated orbital slot at 74 degree East longitude. The satellite is expected to reach its space home by September 24, 2002 where it will be arrested.

The spacecraft, which had 560 kg of propellant at the time of its injection into Geo-synchronous Transfer Orbit by PSLV, has still about 100 kg of propellant left, which will be sufficient for its station keeping operations during its design mission life of 7 years.

In a three-hour operation, which started at 6 am this morning (September 16, 2002), METSAT was put in three-axes stabilised mode. In this mode, the satellite is locked on to earth continuously with the help of its optical sensors and its orientation is maintained to look at the earth in a stable manner using Momentum Wheels, which rotate at 4,500 revolutions per minute to provide gyroscopic stiffness.

The meteorological instrument, namely, the Very High Resolution Radio Meter on board the satellite will be operated following in-orbit testing of the satellite once it reaches its designated orbital slot.