An OPS-SAT mission is any mission that supports ESA's OPS-SAT Space Lab Service. These missions are specially designed for in-flight experimentation, including powerful, reconfigurable units running standard software e.g. Linux, Python, FPGAs etc. The missions are used for in-flight experimentation not possible or desirable on other missions and require no charge, contract or paperwork. OPS-SAT Space Lab has three missions that are currently open for experiment registration; OPS-SAT PRETTY, OPS-SAT VOLT, and OPS-SAT ORIOLE.