plan ERS-1: an expert planning system for generating spacecraft mission plans

Presents a project within the European Space Agency´s Advanced Systems and Technology Programme, which is developing a knowledge based system for planning missions of the European Earth Resource Observation satellite (ERS-1). The aim of the prototype system is to provide the user group with a versatile and flexible tool, which can be applied initially as a mission analysis tool and possibly, upon proper verification, as a mission planning tool. A basic idea of the system is to provide the users with one or more rule-like formalisms for expressing the overall planning and scheduling methodology plus the constraint and conflict resolution mechanisms used in the plan construction. A more general aim of the project is to assess the applicability of knowledge-based and artificial intelligence methodologies for space-related planning problems, and to identify the advantages and drawbacks of such approaches. An initial version of the prototype system has been implemented, which can handle a wide range of the constraints and resources which will eventually be used in the planning process. It includes also initial formalisms for expressing constraints, descoping rules and scheduling strategies