CAN as a spacecraft communication bus in LEO satellite mission

Low Earth orbits (LEO) typically ranges from an altitude of 100 kms to 1000 kms above the surface of Earth. LEO has a typical inclination angle ranging from 95 to 105. Satellite Mission objectives, in these orbits, are mainly Earth observation and remote sensing. In general, such missions provide greater details of the planet Earth to its inhabitants for monitoring and managing their resources effectively. In particular, the engineering of these missions poses more challenges to its designers & developers. Remote sensing satellites enhance the complexity of spacecraft architecture because of the constraints of sophisticated Payload & subsidiary electronics and telemetry data acquisition in a limited time slot during satellite passes over ground segment, which requires lots of buffering. Spacecraft communication Bus is an integral part of satellite, used for low. level word-oriented data acquisition & control as well as higher-level packet transfers amongst different modules of satellite subsystems. This paper describes the utilization of controller area network (CAN) as a Spacecraft communication Bus and discusses different design aspects of CANbus network for Pakistan's Remote Sensing Satellite. Presented is the design of CANbus Network for Telemetry & telecommand for On-Board Data handling. The system is a Multi-master distributed Network that follows the broadcast communication mechanism. That is, the information is being transmitted to all nodes in the network. Every Node receives the same data at same time & filters out unwanted messages. A brief introduction of CAN protocol's flexibility and working mechanism is provided in the beginning of this paper. Next is the Experimental setup arranged in which this protocol is being implemented to verify bus design aspects and results are discussed. In the end, we conclude with our observation about CAN's behavior as a spacecraft communication bus.