The complexity of space missions arises from a myriad of requirements, dependencies, and interfaces that are dealt with collaboratively by experts of different fields. The exchange of information via documents in textual form is usual, however when dealing with complex missions this approach has many disadvantages. Besides the interpretability of natural language, text does not allow for an abstraction of circumstances. This means that the different experts that are involved have to filter out the relevant information in a painstaking process.
Instead of documents, Model-based Systems Engineering (MBSE) uses formalized data models describing requirements, structure, and behaviour. This makes it easier to visualize complex matters in a better way (e.g. by means of the modelling language SysML) as it allows blanking out unneeded details. Applied changes always flow back into the overall model which facilitates automated plausibility checks and error analyses. MBSE makes it possible to support systems engineering starting from the early concept phase through design and implementation, right up to the verification and validation of the product created.
One of the tools for MBSE is a software product called Virtual Satellite that has been developed by the DLR Institute for Software Technology. Virtual Satellite supports the common effort for a uniform digital representation, as well as flexible extensions of the basic data model with required functionalities.
The Galileo Competence Center is using Virtual Satellite for the modelling of the planned project COMPASSO. On board the International Space Station (ISS), the COMPASSO payload will verify optical clock technologies, and a laser communication terminal for optical data transfer, time synchronization, and distance determination. The goal is to ensure and to efficiently manage the future functionality and reliability of the project during its development with MBSE.