APPLE (ARIANE PASSENGER PAYLOAD EXPERIMENT)

APPLE was an experimental communication satellite successfully launched by Ariane-1, from Kourou, French Guiana on June 19, 1981.The spacecraft bus was cylindrical with a diameter of 1.2 metre and a height of 1.2 metre. The communications payload consisted of two 6/4GHz transponders connected to a 0.9 metre diameter parabolic antenna. APPLE successfully served as a test bed for the entire Indian telecommunications space relay infrastructure despite the failure in deployment of one solar panel. Solid Fuel Apogee Kick Motor was used for orbit raising. Initial phase of the operation used spin mode and later part was 3-axes stabilized. SHAR ground station was used for all the mission activities. APPLE was used in several communication experiments including relay of TV programmes, and radio networking. It was used to carry out extensive experiments on time, frequency and code division multiple access systems, radio networking computer inter connect, random access and pockets switching experiments. It also provided an opportunity to introduce state-of-the-art technologies of the day, such as momentum biased three axis stabilization techniques, motor driven deployed solar array, earth sensing for attitude control, C-band transponder design, inclusive of composite reflector, orbit raising, station acquisition, station-keeping and a host of mission management and flight dynamic techniques.