ALBERT

Description: The small, chemically primitive objects of the solar system, comets and asteroids, are one of the most important frontiers remaining for future planetary exploration. So stated the Solar System Exploration Committee of the NASA Advisory Council in its 1986 report 'Planetary Exploration Through the Year 2000.' The Halley's comet flyby missions completed last spring raised more questions than were answered about the nature of comets. The next mission to a comet must be able to explore some of these questions. In the late 1990's, a spacecraft might be built to explore the hazardous area surrounding a comet nucleus. Rigorous pointing requirements for remote sensing instruments will place a considerable burden on their attendant control systems. To meet these requirements we have pursued the initial design and analysis of a multi-bodied comet explorer spacecraft. Sized so as to be built on-orbit after the space station is operational, the spacecraft is comprised of Orbit Replaceable Unit (ORU) subsystems, packaged into two major components: a three-axis controlled instrument platform and a spinning, detached comet dust shield. Such a configuration decouples the dynamics of dust impaction from the stringent pointing out requirements of the imaging experiments. At the same time, it offers an abundance of simple analysis problems that may be carried out by undergraduates. These problems include the following: Selection of subsystem components, sizing trade studies, investigation of three-axis and simple spin dynamics, design of simple control systems, orbit determination, and intercept trajectory generation. Additionally, such topics as proposal writing project management, human interfacing, and costing have been covered. A new approach to design teaching has been taken, whereby students will 'learn by teaching.' They are asked to decompose trade options into a set of 'if-then' rules, which then 'instruct' the Mechanically Intelligent Designer (MIND) expert design system in how to carry out a design.