2 lines about the Apple satellites

The Ariane Passenger Payload Experiment (APPLE) was ISRO's first indigenous, experimental communication satellite. It was launched into GTO (Geosynchronous Transfer Orbit) by the third development flight of ESA'a Ariane vehicle from Kourou on June 19, 1981. It was boosted into Geo-synchronous Orbit (GEO) by apogee motor of ISRO, derived from fourth stage motor of SLV-3.

Ariane personnel in front of APPLE satellite (with square solar panels)- Courtesy: Ariane Space

Weight	670 kg
Mission	Experimental geostationary communication
mission life	2 years
onboard power	210 watts
stability	Three axis stabilized (biased momentum) with Momentum Wheels, Torquers & Hydrazine based Reaction control system
Manufacturer	ISRO
payload	C - band transponders (Two)
Launch vehicle	Ariane -1(V-3)
Launch date	June19,1981
launch place	Kourou (CSG), French Guyana

APPLE was designed and built in just two years with limited infrastructure in industrial sheds. It gave ISRO valuable hands on experience in designing and developing three-axis stabilized geostationary communication satellites as well as in orbit raising manoeuvres, in orbit deployment of appendages, station keeping, etc.

APPLE was used for nearly two years to carry out extensive experiments on time, frequency and code division multiple access systems, radio networking computer interconnect, random access and pockets switching experiments.