Introduction:
India's first geostationary experimental communication satellite project was the APPLE (Ariane Passenger Payload Experiment) satellite. It was a collaborative effort between the Indian Space Research Organisation (ISRO) and the European Space Agency (ESA).

Background:
During the 1970s, India was making significant progress in space technology and was keen on launching its own satellite. The APPLE satellite project aimed to test and validate various communication technologies and systems that would be crucial for India's future communication satellites.

Details:
The APPLE satellite was designed to be a multipurpose satellite that would serve as a platform for testing and validating various communication technologies. It was based on the European Space Agency's experimental geostationary satellite, ECS-1.

Objectives:
The main objectives of the APPLE satellite project were as follows:
- To demonstrate and validate the technologies required for communication satellite systems.
- To test and evaluate various communication payloads, including transponders, antennas, and communication systems.
- To provide valuable data and insights for the development of future communication satellites by ISRO.

Launch and Specifications:
The APPLE satellite was launched on June 19, 1981, aboard the Ariane-1 rocket from the Kourou spaceport in French Guiana. It had a launch mass of approximately 670 kg and was placed in a geostationary transfer orbit. The satellite had a design life of one year.

Communication Systems:
The APPLE satellite carried various communication payloads, including a C-band transponder, a S-band transponder, and a Very Long Baseline Interferometry (VLBI) experiment. These payloads helped in testing and validating different communication technologies and systems.

Significance:
The successful launch and operation of the APPLE satellite marked a significant milestone for India's space program. It demonstrated India's capability to develop and launch its own communication satellites and paved the way for future advancements in satellite communication technology.

Conclusion:
The APPLE satellite was India's first geostationary experimental communication satellite project. It played a crucial role in testing and validating various communication technologies and systems, providing valuable data and insights for the development of future communication satellites. The successful launch and operation of APPLE marked a major achievement for India's space program and showcased the country's growing prowess in space technology.