Coordinating Space Telescope Operations in an Integrated Planning and Scheduling Architecture

This paper describes HSTS (Heuristic Scheduling Testbed System), a software architecture for integrated planning and scheduling. HSTS has been applied to the problem of generating observation schedules for the Hubble Space Telescope. This problem is representative of the class of problems that HSTS tries to address: their complexity lies in the interaction of resource allocation and auxiliary task expansion. HSTS deals with this interaction by viewing planning and scheduling as two complementary aspects of the more general process of constructing behaviors of a dynamical system. First, the paper describes the principal components of the HSTS software architecture, indicating (1) how to model the structure and dynamics of a system in HSTS, (2) how to represent schedules at multiple levels of abstraction in the HSTS temporal data base, and (3) how the problem solving machinery that is provided operates. The paper then discusses a scheduler for the detailed management of Hubble Space Telescope operations that has been developed within HSTS. Experimental performance results are given that indicate the utility and practicality of the approach