The On-Board Computer of the AcubeSAT Mission

AcubeSAT is an open-source CubeSat mission aiming to explore the effects of microgravity and radiation on eukaryotic cells using a compact microfluidic lab-on-a-chip platform. It is developed by SpaceDot, a volunteer, interdisciplinary student team at the Aristotle University of Thessaloniki and supported by the "Fly Your Satellite! 3" program of the European Space Agency (ESA) Education Office. The nanosatellite features an in-house designed on-board computer subsystem responsible for telecommand execution, telemetry fetching, onboard time synchronization, in-orbit patching, and fault recovery. The subsystem is designed on one PC/104 standard compatible Printed Circuit Board (PCB) that hosts the On-board Computer (OBC) on the one side and the Attitude and Orbit Control Subsystem (AOCS) on the other, and it is compatible with the LibreCube standard. The hosted subsystems are functionally isolated and feature an ARM Cortex-M7, radiation-tolerant microcontroller each. Before sending anything to space thorough testing is required and specifically the on-board computer board underwent vibration and thermal cycling tests to ensure nominal operation in all conditions. This paper aims to elucidate the decision-making process, design iterations, and development stages of the custom board and accompanying in-house software. Insights garnered from the initial partially successful environmental test campaign at the ESA CubeSat Support Facility will be shared, along with the ensuing preparations, results, and lessons learned from subsequent testing endeavors in April 2024. Furthermore, the current developmental status will be discussed alongside future electromagnetic compatibility testing, integration plan on a FlatSat, and prospects for the open-source design as a cost-effective, and modular solution that can be tailored with little effort for upcoming missions.