This decade was primarily devoted for laying a sound technical foundation on satellite technology through conducting large scale experiments involving experimental satellites like Aryabhata, Bhaskara, Rohini and APPLE, development of a modest launch Vehicle SLV-3 and practical demonstration of the benefits of remote sensing of natural resources from the remote sensing satellites. Full scale operationalisation of space technology on a totally self-reliant basis which began around 1980’s, has truly revolutionized the Indian society by enabling even its grassroots to significantly benefit from the application of satellite technology.
India entered into the space age by launching its first scientific satellite, Aryabhata on April 19, 1975 with the assistance of a Soviet booster-rocket. It was the heaviest satellite i.e. 360 kg in weight and 1.2m high with 26 faces. It was powered by silicon solar cell arrays and nickel-cadmium batteries. The satellite was designed to conduct experiments in X-rays, astronomy and physics. Though its active life span was calculated for only six months. The satellite continued in good shape giving its telemetry data till the end of March 1980. The satellite was sending data to tracking station at Sriharikota for analysis.
Bhaskara-I & II:
With the experience gained in Aryabhata, Bhaskar-I was launched in June, 7, 1979, again from the USSR. Bhaskar-II was launched in November 20, 1981. Bhaskara was similar to Aryabhata in many respects. But the main differences were in the Aryabhata payload. It was more sophisticated than Aryabhata. It had two TV cameras in visible and infrared bands, microwave radiometers, tape recorders, data collection platforms and other equipments. It was decided that this satellite would carry remote sensing sensors which would detect and assess natural resources like land, water, forest and ocean. Ground stations at Sriharikota and Ahemadabad handled the reception data and control.
Rohini Satellites (RS):
Rohini-I (RS-I) was the first Indan satellite launched from Sriharikota by India’s own launch vehicle, SLV-3 in 1980. Its main objective was to evaluate the performance of the fourth stage of SLV-3 launch vehicle and monitor important parameters such as velocity, separation shock, pressures and temperatures. Though the original life of RS-I was estimated 100 days, but it remained in orbit for more than a year. On July 24, 1981 it re-entered into the earth and burnt out completely. But before that, it fulfilled all the mission goals by providing useful data.
RS-DI, the second satellite of RS series was launched by SLV-3 on 31 May, 1981. The satellite carried a new remote sensing device called landmark sensor as its main payload. Unfortunately, the satellite was injected to a lower orbit. Hence after nine days the satellite burnt up in space on June 9, 1981 without fulfilling its mission.
The third one, Rs-D2, launched by SLV in April, 1983 had a successful mission. It carried a two band imaging system called the SAMRAT sensor, which could identify and image certain land features.
A new series of Rohini Satellite i.e. Stretched Rohini Satellite Series (SROSS) had been planned to be launched by the ASLV (Augmented Satellite Launching Vehicle) for space science, technology and applications. But the ASLV mission to launch SROSS-1 in March, 1987 and SROSS-2 in July, 1988 failed. However, SROSS-3 was launched successfully on May 19, 1992.
APPLE (Arianne Passenger Payload Experiment) : Successful launch of the Arianne Passenger Payload Experiment (APPLE), India’s first experimental communication satellite on the European Arianne Launch Vehicle on June 19, 1981, was another significant milestone in India’s space research. APPLE had been used successfully to conduct experiments in communication relating to domestic communication. Radio and TV networking, data relay, remote area communication etc. APPLE had two C-band transponder.
It gave ISRO experience not only in building a 3-axis stabilized geostationary satellite but also in orbit rising and geostationary station keeping. Major equipments used in APPLE were built indigenously.
INSAT System : The Indian National Satellite (INSAT) system is a multipurpose geostationary satellite system operating for domestic telecommunication, nationwide direct satellite T.V. telecasting, meteorological observations and data collections and radio-television programme distributions.
INSAT is a joint venture of Department of Space (DOS) Department of Telecommunication (DOT), Indian Meteorological Department (IMD), Al] India Radio (AIR) and Doordarshan. The Master Control Facility of INSAT system is located at Hassan (Karnataka).
The INSAT system was established in 1983, when the INS AT-IB satellite was commissioned successfully and served well. Earlier INSAT-1A, which was launched in 1982, failed miserably. All satellites of INS AT-1 series are of first generation category. All total there are fourth INSAT satellite i.e. IA, IB, 1C and ID. They were built outside India by the Ford Aerospace and Communications Corporation (FACC) according to India specifications. Their main operation is in communications.
The INS AT-1 series is now being replaced by second generation INSAT satellite i.e. INSAT-2 series with five satellites out of which four namely INSAT-2A, 2B, and 2C have already been launched successfully. INSAT-2D has been launched recently on June 4, 1997 at 5.18 a.m. from Kourou (French Guinea) and is working successfully. INSAT-2 series satellites are designed and developed indigenously and are multipurpose operational satellite system for telecommunication, T.V. and radio broadcasting and meteorology. They are more complex in comparison to INS AT-1 series satellites and have 18 transponders in the C band/ extended C band, two S-band high power transponders, one data relay transponder and a search and rescue payload (SAR) in the communication segment and a Very High Resolution Radiometer (VHRR) in two spectral bands for meteorological imaging.