48 degree

Indian National Satellite System

INSAT or the Indian National Satellite System is a series of multipurpose Geo-Stationary satellites launched by ISRO to satisfy the telecommunications, broadcasting, meteorology, and "search and rescue" needs of India. Commissioned in 1983, INSAT is the largest domestic communication system in the Asia-Pacific Region. It is a joint venture of the Department of Space, Department of Telecommunications, India Meteorological Department, All India Radio and Doordarshan. The overall coordination and management of INSAT system rests with the Secretary-level INSAT Coordination Committee.

INSAT satellites provide 199 transponders in various bands (C, S, Extended C and Ku) to serve the television and communication needs of India. Some of the satellites also have the Very High Resolution Radiometer (VHRR), CCD cameras for metrological imaging. The satellites also incorporate transponder(s) for receiving distress alert signals for search and rescue missions in the South Asian and Indian Ocean Region, as ISRO is a member of the Cospas-Sarsat programme.

INSAT system

The Indian National Satellite (INSAT) system was commissioned with the launch of INSAT-1B in August 1983 (INSAT-1A, the first satellite was launched in April 1982 but could not fulfill the mission). INSAT system ushered in a revolution in India’s television and radio broadcasting, telecommunications and meteorological sectors. It enabled the rapid expansion of TV and modern telecommunication facilities to even the remote areas and off-shore islands. Today, INSAT has become the largest domestic communication satellite system in the Asia-Pacific region with ten satellites in service -- INSAT-2E, INSAT-3A, INSAT-3B, INSAT-3C, INSAT-3E, KALPANA-1, GSAT-2, EDUSAT, INSAT-4A and INSAT-4B. Together, the system provides 199 transponders in C, Extended C and Ku bands for a variety of communication services. Some of the INSATs also carry instruments for meteorological observation and data relay for providing meteorological services. KALPANA-1 is an exclusive meteorological satellite. The satellites are monitored and controlled by Master Control Facilities that exist in Hassan and Bhopal.

INSAT satellites

Sl. No. Satellite Launch Date Mission Status
1 INSAT-1A 10 April,1982 Deactivated on 6 September,1982
2 INSAT-1B 30 August,1983 Completed mission life
3 INSAT-1C 22 July,1988 Abandoned in November 1989
4 INSAT-1D 12 June,1990 Completed mission life
5 INSAT-2A 10 July,1992 India's First Indegenious communication Satellite. Completed mission life
6 INSAT-2B 23 July,1993 Completed mission life
7 INSAT-2C 7 December,1997 Completed mission life
8 INSAT-2D 4 June,1997 Became inoperable on 4 October,1997
9 INSAT-2DT In-orbit procurement Completed mission life
10 INSAT-2E 3 April,1999 In service
11 INSAT-3A 10 April,2003 In service
12 INSAT-3B 22 May,2000 In service
13 INSAT-3C 24 January,2002 In service
14 KALPANA-1 12 September,2002 In service
15 GSAT-2 8 May,2003 In service
16 INSAT-3E 28 September,2003 In service
17 EDUSAT 20 September,2004 In service
18 INSAT-4A 22 December,2005 In service
19 INSAT-4C 10 July,2006 Not placed in orbit due to launch failure of GSLV-F02
20 INSAT-4B 12 March,2007 In service
21 INSAT-4CR 2 September,2007 in geo-synchronous orbit

Satellites in service

There are currently 11 satellites in service out of 21 which have ever been part of INSAT system.


It is the last of the five satellites in INSAT-2 series. It carries seventeen C-band and lower extended C-band transponders providing zonal and global coverage with an Effective Isotropic Radiated Power (EIRP) of 36 dBW. It also carries a Very High Resolution Radiometer (VHRR) with imaging capacity in the visible (0.55-0.75 µm), thermal infrared (10.5-12.5 µm) and water vapour (5.7-7.1 µm) channels and provides 2x2 km, 8x8 km and 8x8 km ground resolution respectively. In addition to the above two payloads it has with it a Charge Coupled Device (CCD) camera providing 1x1 km ground resolution in the Visible (0.63-0.69 µm), Near Infrared (0.77-0.86 µm) and Shortwave Infrared (1.55-1.70 µm) bands.

INSAT-3 Series


The multipurpose satellite, INSAT-3A, was launched by Ariane in April 2003. It is located at 93.5 degree East longitude. The payloads on INSAT-3A are as follows:

  • 12 Normal C-band transponders (9 channels provide expanded coverage from Middle East to South East Asia with an EIRP of 38 dBW, 3 channels provide India coverage with an EIRP of 36 dBW and 6 Extended C-band transponders provide India coverage with an EIRP of 36 dBW).
  • 6 Ku-band transponders provide India coverage with EIRP of 48 dBW.
  • A Very High Resolution Radiometer (VHRR) with imaging capacity in the visible (0.55-0.75 µm), thermal infrared (10.5-12.5 µm) and Water Vapour (5.7-7.1 µm) channels, provide 2x2 km, 8x8 km and 8x8 km ground resolutions respectively.
  • A CCD camera provides 1x1 km ground resolution, in the visible (0.63-0.69 µm), near infrared (0.77-0.86 µm) and shortwave infrared (1.55-1.70 µm) bands.
  • A Data Relay Transponder (DRT) having global receive coverage with a 400 MHz uplink and

4500 MHz downlink for relay of meteorological, hydrological and oceanographic data from unattended land and ocean-based automatic data collection-cum-transmission platforms.

  • A Satellite Aided Search and Rescue (SAS&R) SARP payload having global receive coverage with 406 MHz uplink and 4500 MHz downlink with India coverage, for relay of signals from distress beacons in sea, air or land.. See also Cospas-Sarsat.


Launched in March 2000, INSAT-3B is collocated with INSAT-2E at 83 degree East longitude. It carries 12 Extended C-band transponders and three Ku-band transponders that have coverage over the Indian region. INSAT-3B also incorporates a Mobile Satellite Services (MSS) payload with forward link between the hub and mobile station operating in CxS band and return link between the mobile station and the hub operating in SxC band.


Launched in January 2002, INSAT-3C is positioned at 74 degree East longitude. INSAT-3C payloads include 24 Normal C-band transponders providing an EIRP of 37 dBW, six Extended C-band transponders with EIRP of 37 dBW, two S-band transponders to provide BSS services with 42 dBW EIRP and an MSS payload similar to that on INSAT-3B. All the transponders provide coverage over India.


Launched in September 2003, INSAT-3E is positioned at 55 degree East longitude and carries 24 Normal C-band transponders provide an edge of coverage EIRP of 37 dBW over India and 12 Extended C-band transponders provide an edge of coverage EIRP of 38 dBW over India.


KALPANA-1 is an exclusive meteorological satellite launched by PSLV in September 2002. It carries VHRR and DRT payloads to provide meteorological services. It is located at 74 degree East longitude.


Launched by the second flight of GSLV in May 2003, GSAT-2 is located at 48 degree East longitude and carries four Normal C-band transponders to provide 36 dBW EIRP with India coverage, two Ku-band transponders with 42 dBW EIRP over India and an MSS payload similar to those on INSAT-3B and INSAT-3C.


Configured for audio-visual medium employing digital interactive classroom lessons and multimedia content, EDUSAT was launched by GSLV in September 2004. Its transponders and their ground coverage are specially configured to cater to the educational requirements. The satellite carries a Ku-band transponder covering the Indian mainland region with 50 dBW EIRP, five Ku-band spot beam transponders for South, West, Central, North and North East regional coverage with 55 dBW EIRP and six Extended C-band transponders with India coverage with 37 dBW EIRP. EDUSAT is positioned at 74 degree East longitude and is collocated with KALPANA-1 and INSAT-3

INSAT-4 Series


Launched in December 2005 by the European Ariane launch vehicle, INSAT-4A is positioned at 83 degree East longitude along with INSAT-2E and INSAT-3B. It carries 12 Ku-band 36 MHz bandwidth transponders employing 140 W TWTAs to provide an EIRP of 52 dBW at the edge of coverage polygon with footprint covering Indian main land and 12 C-band 36 MHz bandwidth transponders provide an EIRP of 39 dBW at the edge of coverage with expanded radiation patterns encompassing Indian geographical boundary, area beyond India in southeast and northwest regions.. Tata Sky, a joint venture between the TATA Group and STAR uses INSAT-4A for distributing their Direct To Home Digital Television services across India.


It was launched in March 2007 by the European Ariane launch vehicle. Configured with payloads identical to that of INSAT-4A, INSAT-4B carries 12 Ku-band and 12 C-band transponders to provide EIRP of 52 dBW and 39 dBW respectively. Two Tx/Rx dual grid offset fed shaped beam reflectors of 2.2 m diameter for Ku-band and 2 m diameter for C-band are used. INSAT-4B augments the high power transponder capacity over India in Ku-band and over a wider region in C-band. It is co-located with INSAT-3A at 93.5 degree E longitude.


INSAT-4C was to be India's most advanced communications satellite, and was the second satellite in the INSAT 4 series.

The heaviest satellite to be launched from the Indian soil, INSAT-4C weighed 2168 kg, and was designed to last for 10 years. The satellite would have given a boost to Direct-to-Home television services, video picture transmission and digital satellite news gathering, and would have also provided space for National Informatics Centre's VSAT connectivity.

India launched the INSAT 4C on July 10, 2006 from Sriharikota at 5:38pm. However, the launch was unsuccessful as the Geo-synchronous Satellite Launch Vehicle (GSLV-F02) carrying the satellite veered from its projected path 60 seconds after launch, and was self-destructed over the Bay of Bengal.

The failure is being attributed to pressure of one of the strap-on motors dropping to zero pressure in the first stage of operation, Thus causing it to deviate it from its path by 10 degrees.


INSAT-4CR was launched on 2 September 2007 by GSLV-F04. It is a replacement satellite of INSAT-4C which was lost when GSLV-F02 failed and had to be destroyed on its course. It carries 12 Ku-band 36 MHz bandwidth transponders employing 140 W TWTAs to provide an Effective Isotropic Radiated Power of 51.5 dBW at Edge of Coverage with footprint covering Indian mainland. It also incorporates a Ku-band Beacon as an aid to tracking the satellite. On 8 September 2007 ISRO reported the satellite had reached a near geosynchronous orbit, and would be stabilized in its intended orbital position of 74 degrees E longitude by September 15. The satellite is designed for a mission life in excess of ten years.


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