| The challenges associated with constructing interplanetary spacecraft and space platforms in low earth orbit are such that it is imperative that comprehensive, preliminary process planning analyses be completed before committing funds for Phase B design (detail design, development). Phase A and "pre-Phase A" design activities will commonly address engineering questions such as mission-design structural integrity, attitude control, thermal control, etc. But the questions of constructability, maintainability and reliability during the assembly phase usually go unaddressed until the more mature stages of design (or very often production) are reached. This is an unacceptable strategy for future space missions whether they be government or commercial ventures.;After interviews with expert Aerospace and Construction industry planners a new methodology was formulated and a Blackboard Metaphor Knowledge-based Expert System synthesis model has been successfully developed which can decompose interplanetary vehicles into deliverable orbital subassemblies. Constraint propagation, including launch vehicle payload shroud envelope, is accomplished with heuristic and numerical algorithms including a unique adaptation of a reasoning technique used by Stanford researchers in terrestrial automated process planning. The model is a hybrid combination of rule and frame-based representations, designed to integrate into a Computer-Aided Engineering (CAE) environment. Emphasis is placed on the actual joining, rendezvous, and refueling of the orbiting, dynamic spacecraft.;Significant results of this new methodology upon a large Mars interplanetary spacecraft (736,000 kg) designed by Boeing, show high correlation to manual decomposition and planning analysis studies, but at a fraction of the time, and with little user interaction. Such Computer-Aided Engineering (CAE) tools would greatly leverage the designers ability to assess constructability. |
