Reliability is one of the most important quality elements of satellite software. Satellite software usually runs on special hardware. In this article we consider a sample LEO satellite software as our case study. The software of this satellite runs on a Transputer based hardware utilizing the Virtuoso operating system which has limited development capabilities. Virtuoso is a real time multitask operating system and VirSim is produced by simulating the virtuoso services in Windows platform. Any software which is developed in the VirSim environment can be used in the original environment with a few changes. This tool increases software development rate and improves its reliability. In this article, we discuss the VirSim environment from a theoretical and application point of view, and explain the results for satellite software. Attitude Control System (or ACS) software is one of the main parts of on-board software. In this article we describe a new software tool for developing and testing the ACS software, as the case study of VirSim tool, with emphasis on the real-time and multitask software architecture, which we call “VirSim_ACS”. The tool is an integrated development environment (IDE) which includes: the ACS software, a part for simulating the onboard operating system (OS) and a part which simulates the satellite’s space dynamic. This facility can be used for end-to-end tests on the ACS software of satellites. This tool has passed Verification and validation tests. Test results show that the production is reliable enough to be used in ACS software development and debugging.
VirSim, Development Environment, Virtuoso, Attitude Control Subsystem, LEO Satellite, Multitask OS, Simulator.