Mission Planning is an area for which no official reusable infrastructure exists. This contrasts with Mission Control Systems and simulators where reusable kernels have been used for many years and are in some cases in their third generation. However there have been successful examples of reuse of mission planning systems and this paper describes the most recent one. It shows the evolution of the MPS starting from the first study targeting a “Generic Mission Planning Facilities”, which began in 1995, to more sophisticated systems like Envisat, which is a very complex mission from the planning point of view, or Mars Express, which is the most recent one. The resulting “MPS Kernel” will be detailed. All along, the major motivation for this evolutions were costs reduction imposed by short timescales available for the developments. The goal has been achieved whilst keeping a high level of quality in all aspects of the missions. Technical choices were made in order to reduce the licensing costs, and the design of the software did target the reuse of modules between missions. Furthermore, extending the initial idea of a generic tool, the configurability of the MPS has been significantly enhanced in the sense that numerous possible changes coming from the users community, can be integrated to the software just by editing configuration files, without changing the source code itself. This paper will finally shows the different possibilities of expansion of the actual kernel and the different studies proposed on the subject. Lessons may be drawn for the goal of a reusable MPS infrastructure.