For the past four decades, ISRO has launched more than 50 satellites for various scientific and technological applications like mobile communications, Direct-to-Home services, meteorological observations, telemedicine, tele-education, disaster warning, radio networking, search and rescue operations, remote sensing and scientific studies of the space.

ISRO has established two major space systems-

• The Indian National Satellite System (INSAT) series for communication, television broadcasting and meteorological services which is Geo-Stationary Satellites
• The Indian Remote Sensing Satellites (IRS) system for resources monitoring and management which is Earth Observation Satellites

ISRO has launched many Experimental Satellites which are generally small comparing to INSAT or IRS and Space Missions to explore the space.

The Indian National Satellite (INSAT)

The Indian National Satellite (INSAT) system which are placed in Geo-stationary orbits is one of the largest domestic communication satellite systems in Asia-Pacific region. Established in 1983 with commissioning of INSAT-1B, it initiated a major revolution in India’s communications sector and sustained the same later. INSAT space segment consists of 24 satellites out of which 9 are in service (INSAT-2E, INSAT-3A, INSAT-4B, INSAT-3C, INSAT-3E, KALPANA-1, GSAT-2, INSAT-4A and INSAT-4CR ) 

The system with a total of nearly 200 transponders in the C, Extended C and Ku-bands.provides services to telecommunications, television broadcasting, weather forecasting, disaster warning and Search and Rescue operations.