INSAT-1A Launch Anniversary: 10 Things To Know About The Indian Communications Satellite

INSAT-1A was an Indian communications satellite launched on April 10, 1982, as part of Indian National Satellite System or the INSAT-1 program.

Delta 3910 rocket (left) (Credit: Wikimedia Commons); INSAT-1A satellite (right) (Credit: ISRO)

New Delhi: INSAT-1A was an Indian communications satellite launched on April 10, 1982 as part of Indian National Satellite System or the INSAT-1 program. This year, April 10 marks the 40th anniversary of the satellite's launch.

The INSAT-1 program incorporated two three-axis stabilised spacecraft in geostationary orbit, namely INSAT-1A and INSAT-1B, with a host of ground stations throughout India, according to NASA.

Here are ten facts you need to know about INSAT-1A.

1. The INSAT-1A satellite was built by the Ford Aerospace and Communications Corporation, and was designed to provide combined telecommunications, direct television broadcast, and  meteorological service to India's civilian community.
2. INSAT-1A was launched on April 10, 1982, using a Delta 3910 rocket with a PAM-D upper stage, from Launch Complex 17A at Cape Canaveral Air Force Station, United States. PAM or Payload Assist Module is a portable launch platform for helping launch small satellites with the Space Shuttle, Delta, and Titan launchers, and carrying satellites from low-Earth orbit to a geostationary transfer orbit. 
3. The satellite had a mass of 1152.1 kilograms.
4. The telecommunications package of INSAT-1A provided two-way, long distance telephone circuits and direct radio and television broadcasting to the remotest areas of India. It had 12 transponders operating at certain frequencies for remote area communication and television program distribution. It had two transponders for direct broadcasting to augmented low-cost community television sets in rural areas, radio-program distribution, national television networking, and disaster warning.

5. The data collection and transmission package of INSAT-1A consisted of a data channel to provide for the relay of meteorological, hydrological, and oceanographic data from unattended land-based and ocean-based data collection and transmission platforms.
6. The meteorology package was composed of a scanning very-high-resolution, two-channel radiometer (VHRR) to provide full frame, full-Earth coverage every 30 minutes. The visible channel had a 2.75-kilometre resolution, and the infrared channel had an 11-kilometre resolution. 
7. These observations were used for monitoring weather systems over land and sea. For instance, cyclones could be observed, and sea surface and cloud top temperatures could be measured.
8. Early warnings of impending disasters such as floods and storms could directly reach the civilian population, even in remote areas, using the INSAT television capability.
9. INSAT-1A had some initial difficulties deploying its antennas and solar array, following launch. For 12 days, the C-band antenna could not be deployed, and the solar array was unable to extend fully. This prevented INSAT-1A from generating enough power to conduct weather observations.
10. Subsequently, the satellite's transponders overheated and failed. The satellite's primary earth-tracking sensor was deactivated on September 4, 1982, to protect the system while the Sun passed through its field of view. According to the Indian Space Research Organisation (ISRO), INSAT-1A was abandoned in September 1983 when its altitude control propellant was exhausted.