This paper describes research concerned with automating the monitoring and control of spacecraft systems. In particular, the paper examines the application of SRI’s Procedural Reasoning System (PRS) to the handling of malfunctions in the Reaction Control System (RCS) of NASA’s space shuttle. Unlike traditional monitoring and control systems, PRS is able to reason about and perform complex tasks in a very flexible and robust manner, somewhat in the manner of a human assistant. Using various RCS malfunctions as examples (including sensor faults, leaking components, multiple alarms, and regulator and jet failures), it is shown how PRS manages to combine both goal-directed reasoning and the ability to react rapidly to unanticipated changes in its environment. In conclusion, some important issues in the design of PRS are reviewed and future enhancements are indicated.