An analysis of design reuse in the development of small body nanolander and surface science stations

Abstract

Design reuse, i.e. reuse of design artefacts of space missions is gaining more importance in the frame of cost efficiency improvement i.e. getting more science out of the limited funding in space systems development. This has found application in the Earth orbiting spacecraft sector, but may also be of interest for deep space scientific missons. This thesis contributes to the practice of design reuse with the development and demonstation of a method for a more systematic reuse approach as compared to the ad-hoc reuse widely common. Using a real life reuse case from an ESA phase A mission concept study, the process is described based on a developed general ontology of system design under consideration of the pecularities of a deep space scientific misson and uses Model-Based Systems Engineering methods. A Reuse Matrix has been proposed as a tool to analyse reuse effort a-priori based on individual delta development effort of components and the propagation of changes over the component borders. The latter are shown to be depending on aspects such as the number of interfaces and the number of constraints involved in the change propagation, as well as the extent of change of the latter. Three different case studies are presented: (1) a single reuse scenario, which develops a mission concept for a MASCOT-derived Phobos surface station using the presented method and derives the reuse matrix for this special case; (2) a platform based design-for-reuse analysis, which determines requirements and derives a platform approach for nanolander systems based on the MASCOT lander heritage and (3) a modular lunar infrastructure designed for a special case of reuse of the same system design for different use cases in one mission scenario. The three case studies prove the general applicability of the process and the usability of the Reuse Matrix, which benefits from the existence of a desciptive system model including system requirements, functional breakdown and physical allocation, as well as connected performance models which are fed with the information stored in the system model. The MASCOT lander system design has been demonstrated as very well suited for effective reuse and shows to be a good starting point for a platform-based family of nanolander for a broad variety of small and airless bodies.