Satellite Systems

SATELLITE SYSTEMS

Indian satellite systems fall into two categories; Remote-Sensing & Communications. The main programs being;

INSAT - Indian National Satellite System - The INSAT 1 series

The INSAT system uniquely provides geostationary platforms for simultaneous domestic communications and earth observation functions. The first four generation INSAT series, (INSAT-1A, -1B, -1C and -1D) were all US-built and launched by either US or European space launch vehicles. The INSAT-class satellites are a joint venture of India's Department of Space (DOS), Department of Telecommunications (DET), India Meteorological Deptartment (IMD), All India Radio and Doordarshan. Overall co-ordination & management rests with the inter-ministerial INSAT Coordination Committee (ISS). DOS has direct responsibility for establishing and operating the space segment.

The satellites are handled from the INSAT Master Control Facility (MCF) at Hassan in Karnataka. They can also be controlled through two Satellite Control Earth Stations (one with a 14 metre fully steerable antenna and the other with a 7.5 metre limited steerability dish), one additional 14 metre fully steerable antenna and an INSAT-1 Satellite Control Centre (SCC) with Telemetry Tracking & Control (TTC) equipment, on-orbit checkout equipment, computer facilities and auxiliary power services. The INSAT MCF was upgraded with addition of the INSAT-2 SCC and two associated 11 metre Satellite Control Earth Stations.

INSAT-1A: The INSAT-1A system was envisaged with a space segment comprising two multi-purpose satellites, each providing two high power TV broadcast and twelve telecommunications national coverage transponders, in addition to also providing meteorological services. The INSAT-1A was launched by US Delta in April 1982 but was abandoned in September 1983 when its attitude control propellant was exhausted.

The INSAT-1A Satellite

INSAT-1B: Launched on 30 August 1983 from Canaveral, it almost suffered the same fate as the INSAT-1A. Video recordings suggested that it might have been struck by Orbiter debris during release, though this could not be confirmed. It was not until mid-September that Ford and Indian controllers at Hassan's MCF succeeded in deploying its solar array. By then it had been stationed at 74°E in place of INSAT-1A. Full operational capability was achieved in October 1983. It continued to operate into 1990 with all its 4375 two-way voice or equivalent circuits in use. Around 36,000 earth images were returned.

The INSAT-1B Satellite

Eleven of its 12 C-band transponder and its two S-band transponders provided direct nationwide TV & communications to thousands of remote villages, plus a detailed weather and disaster-warning service. Around 35,000 Indian built 3 to 3.6 metre diameter, earth receive only terminals were in place to supply rural communities with social and educational programs. It was relegated to spare status on 17 July 1990 by the INSAT-1D. The INSAT-1B was finally removed from GEO in August 1993, after being replaced at 93.5°E by INSAT-2B. Total cost of INSAT-1B and its backup INSAT-1C, including the PAM-D launch was estimated at $140 million.

INSAT-1C: The INSAT-1C satellite was launched on 21 July 1988 from Kourou for location at 93.5°E to bring the INSAT system up to full capacity. Half of the 12 C-band transponders and its two S-band transponders were lost when a power system failure knocked out one of the two buses, but the meteorological earth images and its data collection systems were both fully operational. Earth lock was lost 22 November 1989 and the satellite was abandoned. Reported insurance payout was $70 million.

INSAT-1D: The specification for the INSAT-1D is the same as the INSAT-1B but with expanded battery and propellant capacities. Launched on 12 June 1990, from Canaveral, to conclude the first generation INSAT series. Launch was planned for 29 June 1989 but 10 days before it was seriously damaged following installation on the Delta when a 34kg crane hook fell 10m directly on to it. The fully insured satellite was repaired by Ford Aerospace at a reported cost of $10 million. It also suffered $150,000 of damage during the October 1989 Californian Earthquake. It assumed prime role from INSAT-1B on 17 July 1990. Design life is seven years.

INSAT-1D's Transponders;

• Twelve 4.5W TWTA 5935-6425/3710-4200MHz up/down, C-band all-India beam, 36MHz bandwidth, 32dBW EOL EIRP over primary coverage area linear polarisation.

• Two (plus one backup) 50W TWTA 5855-5935/2555-2635MHz up/down, S-band all-India beam, 42dBW EOL EIRP over primary coverage area linear polarisation.

Principle Applications;

Domestic communications on C-band, one S-band channel dedicated to direct TV broadcast and other to five low-level carriers for services such as radio program distribution, disaster warning, etc. They relay 402.75MHz transmissions from 100 hydrological, meteorological and oceanographic data collection platforms.