INSAT-3C: Indian Multipurpose Communications Satellite

Overview
INSAT-3C is a multipurpose communications satellite developed by the Indian Space Research Organisation (ISRO) and launched by Arianespace in January 2002. It is the second satellite in the INSAT-3 series and is designed to provide a wide range of services—including voice, video, and digital data transmission—across India and neighboring countries. The satellite is operated and monitored from ISRO’s Master Control Facility in Hassan, Karnataka.

Launch Details

• Launch date: January 24, 2002

• Launch vehicle: Ariane 4 by Arianespace

• Launch site: Kourou, French Guiana, South America

• Orbit type: Geosynchronous Transfer Orbit (GTO)

• Initial orbit parameters:

  • Perigee: 570 km

  • Apogee: 35,920 km

  • Inclination: 4°

  • Stabilization: 3-axis mode

INSAT-3C was successfully placed into GTO 21 minutes after launch, and later maneuvered to its final geostationary position using its onboard 440 Newton Liquid Apogee Motor (LAM). The spacecraft carried approximately 1.5 tonnes of MMH and MON-3 propellant for orbit-raising, station-keeping, and in-orbit attitude control.

Satellite Platform and Stabilization
INSAT-3C is based on ISRO’s standard 3-axis body-stabilized spacecraft platform, equipped with:

• Momentum/reaction wheels

• Earth and Sun sensors

• Inertial reference units

• Magnetic torquers

• Unified bipropellant thrusters

This robust stabilization system ensures precise satellite orientation and long-term operational reliability.

Payload and Services
INSAT-3C is equipped with a combination of transponders to enhance and extend the capacity of the INSAT satellite system, replacing aging satellites INSAT-2DT and INSAT-2C.

Payload configuration includes:

• 24 C-band transponders (Fixed Satellite Services – FSS), each with an EIRP of 37 dBW

• 6 extended C-band transponders (FSS), also with 37 dBW EIRP

• 2 S-band transponders (Broadcast Satellite Services – BSS) with 42 dBW EIRP

• 1 MSS transponder operating with S-band uplink and C-band downlink

The satellite is positioned near 74° East longitude, serving India and nearby regions with reliable communication services.