Evolution of the Spike Planning and Scheduling System

Glenn Miller, Larry Kramer, Peg Stanley, Tony Krueger, and
Mark Giuliano

Space Telescope Science Institute (STScI)
3700 San Martin Dr.
Baltimore, MD 21218
{miller, kramer, pstanley, krueger, giuliano}@stsci.edu

Abstract

Spike is a general framework for planning and scheduling that was 
developed by the Space Telescope Science Institute for NASA's Hubble 
Space Telescope.  This paper describes how Spike has been adapted to 
different missions and how the overall system has evolved with 
experience.  Major architectural concepts which have emerged include 
the development of the "multistart stochastic repair" constraint 
satisfaction problem-based scheduler from an initial neural network 
approach and the development of planning via "plan windows" to provide 
stable plans in an unstable environment.  In addition to over seven 
years of operational use for HST, Spike has been used for several 
other space- and ground-based observatories, including EUVE, ASCA and 
XTE and will be used in FUSE, AXAF and the ground-based European Very 
Large Telescope.  This paper also illustrates how Spike is adapted to 
new missions.