System control of an autonomous planetary mobile spacecraft

Abstract

Our goal is to suggest the scheduling and control functions necessary for accomplishing mission objectives of a fairly autonomous interplanetary mobile spacecraft, while maximizing reliability. Goals are (1) to provide an extensible, reliable system conservative in its use of on-board resources, while (2) getting full value from subsystem autonomy, and (3) avoiding the lure of ground micromanagement. We propose a functional layout consisting of four basic elements: Ground and System Executive system functions and Resource Control and Activity Manager subsystem functions. The system executive includes six subfunctions: System Manager, System Fault Protection, Planner, Schedule Adapter, Event Monitor, and Resource Monitor. The full configuration is needed for autonomous operation on Moon or Mars, whereas a reduced version without the planning, schedule adaption and event monitoring functions could be appropriate for lower-autonomy use on the Moon. An implementation concept is suggested which is conservative in use of system resources and consists of modules combined with a communications network. The paper introduces a language concept we have termed a “scheduling calculus” for rapidly performing essential on-board schedule adaption functions.