Silver Jubilee of APPLE
APPLE (Ariane Passener Payload Experiment) was the first Indian built experimental communication satellite. It was launched on June 19, 1981 on board the third developmental flight of Ariane from Kourou, French Guyana. The spacecraft was built with limited infrastructure at the industrial sheds of Peenya, Bangalore in just two years to meet the schedule of the newly developed Ariane’s third test flight to make use of the opportunity provided by the European Space Agency to launch the spacecraft free of cost.
With a redundant C-band transponder and limited power of 240 W using two deployable solar panels, the 670 kg APPLE was very modest compared to the present INSATs.
Ariane launched APPLE, along with its two co-passengers – METEOSAT of ESA and Ariane Technology Capsule (CAT) — into an elliptical Geosynchronous Transfer Orbit. A solid propellant Apogee Boost Motor that had been adopted from the fourth stage of India’s first Satellite Launch Vehicle, SLV-3, which was still under development at that time, was used to take APPLE to its final 36,000 km high geosynchronous orbit. It was positioned at 102 deg E longitude.
With one of the two solar panels failing to open up, APPLE had severe constraint of power and also complications in the thermal management and attitude control. In spite of these difficulties, APPLE was in operation for more than two years. A variety of pioneering communication experiments including teleconferencing, computer data transfer, etc, were conducted. Besides, it provided continuity to many other experiments undertaken earlier like Satellite Instructional Television Experiment using NASA’s ATS-6 satellite and Satellite Communications Experiment Project using Franco-German Symphonie satellite.
APPLE laid a firm foundation to ISRO’s geostationary communication satellite programme by providing valuable experience in designing and building a three-axis stabilised geostationary communication satellite, orbit raising manoeuvres, deployment of appendages and station keeping operations besides its application for several communication experiments. The rich experience gained through APPLE enabled India to design and build all its INSATs from the second generation series (INSAT-2) onwards.
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Mr
G Madhavan Nair, Chairman, ISRO with Dr Yannick d’Escatha,
president, CNES (to Mr Nair’s right) and Mr Jean-Yves Le
Gall, CEO, Arianespace at the |
