Avoiding Human Error in Mission Operations - Cassini Flight Experience

Abstract

Operating spacecraft is a never-ending challenge and the risk of human error is everpresent. Many missions have been significantly affected by human error on the part of ground controllers. The Cassini mission at Saturn has not been immune to human error, but Cassini operations engineers use tools and follow processes that find and correct most human errors before they reach the spacecraft. What is needed are skilled engineers with good technical knowledge, good interpersonal communications, quality ground software, regular peer reviews, up-to-date procedures, as well as careful attention to detail and the discipline to test and verify all commands that will be sent to the spacecraft. Two areas of special concern are changes to flight software and response to in-flight anomalies. The Cassini team has a lot of practical experience in all these areas and they have found that well-trained engineers with good tools who follow clear procedures can catch most errors before they get into command sequences to be sent to the spacecraft. Finally, having a robust and fault-tolerant spacecraft that allows ground controllers excellent visibility of its condition is the most important way to ensure human error does not compromise the mission.

Cassini at Saturn Proximal Orbits - Attitude Control Challenges

“…Preparing for anomalies before they happen is vital throughout the Cassini mission. 10 Managing the attitude that will be commanded in the event of safe mode is a key task because all significant anomalies will suspend normal operational command sequences and the spacecraft will autonomously turn to the safing attitude to await ground response. If this safe mode attitude were to present additional complications (for example, blinding the star tracker) it would make it even harder for ground controllers to assess and respond to the original anomaly.…”