Reliability of on-board computer for ITASAT university satellite

Abstract

This paper presents a case study that aims to develop a hardware architecture for the computer to the ITASAT university satellite, based on fault-tolerant architecture and calculations of reliability. The on-board computer of a satellite, inserted into the on Board Management Subsystem, has functions of receiving, processing and distribution of commands to the subsystems and payload of the satellite; and acquiring, formatting, storage and transmission of telemetry from subsystems and payload. The main requirements of an on-board computer are high reliability, capability of real time processing, resistance to radiation, and minimizing power consumption, volume and mass. Increased reliability can be achieved by the fault tolerance technique, which is based on adding redundancy to the system, or the use of components with high value of individual reliability. In this work, hardware redundancy techniques are considered. First, a computer is designed and its reliability is calculated, for a mission of twenty-four months duration. Mission reliability goal is not attained in this calculation. In order to increase reliability, two types of fault tolerant redundant architectures are analyzed, with their respective reliabilities calculated for the same period of the mission.