The introduction of modular satellite systems rep- resents an attractive goal pursued by several aerospace agencies as well as scientific institutions worldwide. Advantages in robustness, long-term use and production are only few examples that speak for modularity. The downside to modularity is the still prevailing complexity of designing satellites and their building blocks. The intelligent Computer Aided Satellite Designer (iCASD) was developed initially to speed up this design process. The tedious work of fitting, placing and integrating multiple components is especially time consuming since every building block comes with often competing restrictions. The presented tool uses the modularity of satellite components, and turns the design process into an abstracted problem capable to be solved by methods such as the proposed genetic algorithm. In this paper, we will present the underlying processes, how building blocks and corresponding rules are modelled and how a optimal configuration is calculated with this comprehensive tool.