ISRO’s latest communication satellite, INSAT-3E, was launched on September 28, 2003 by the Ariane-5 launch vehicle of Arianespace. INSAT-3E is the fourth satellite in the INSAT-3 series; INSAT-3A, INSAT-3B and INSAT-3C were launched on April 10, 2003, March 22, 2000 and January 24, 2002 respectively.

The 162nd flight of Ariane, with ISRO’s 2750 kg INSAT-3E, e-BIRD of EUTELSAT and SMART-1 of European Space Agency, lifted off at 4.44 am IST  from Kourou, French Guyana. Thirty minutes later, INSAT-3E was injected in 3-axis stabilized mode into  a Geosynchronous Transfer Orbit (GTO) with a perigee of 649 km and  an apogee of 35,923 km. The inclination of the orbit was 7 deg with respect to the equator and the orbital period was about 10 hours 50 minutes.

INSAT-3E on assembly Jig

INSAT-3E carries 24 C-band transponders, having India beam coverage providing an Edge of Coverage-Effective Isotropic Radiated Power (EOC-EIRP) of 38.5 dBW and 12 upper extended C-band transponders having India beam coverage providing an (EOC-EIRP) of 38 dBW. The spacecraft has its main body in the shape of a cuboid of dimensions 2.0 m X 1.77 m X 2.8 m with solar arrays on north and south sides. When its solar panels are fully deployed in orbit, it measures 15.44 m (North-South). The satellite is 3-axis body stabilized using sensors, momentum and reaction wheels, magnetic torquers and eight 10 Newton and eight 22 Newton Reaction Control thrusters. The satellite has two solar arrays together generating 2,400 Watt of electrical power backed up by two 70 Ah Nickel Hydrogen Batteries that support full payload operation during eclipse period. The satellite has two deployable antennas and one fixed antenna for various transmit and receive functions.

INSAT-3E inside anechoic chamber

Through a series of complicated maneuvers spanning four days, the Master Control Facility (MCF), Hassan in Karnataka steered INSAT-3E into a near geostationary drift-orbit, successfully deployed its solar panels and antennas and put it in its final three axis stabilised configuration. INSAT-3E carries adequate fuel to complete its design life of 12 years.