Product Verification on Mars Express - Routine Validation to Ensure Routine Success

摘要

Modern space missions have increasingly complex operations, both on-board and on ground. Mars Express is no exception to this rule, with frequent special science operations and a bespoke plan for each individual orbit. While well validated and competent planning systems are the basis on which such operations are built, a routine system of validating the output of such systems is an important component to ensuring safe and successful operations. In this sense we never stop validating on Mars Express and by doing this we are able to ensure a high level of success and minimize and catch errors long before they reach the spacecraft or the ground station. In order to be able to do this for complex and varied operations we employ a multi-layered approach featuring both manual and automatic checks. This paper will describe what these different levels of checking entail and how the decisions have been made on whether or not to automate. This is a dynamic process with automation being consistently introduced when it can provide more efficient and cost-effective than manual checking. One of the major new introductions on Mars Express is a highly configurable state machine engine that is flexible enough to perform a wide number of checks that traditionally have been manual. The design of this tool and its potential will be explored in the paper. As well as the methods and type of checks that are employed on Mars Express; the paper will go into some detail on the underlying reasons for why we consider that careful validation of routine operations products is key to a safe and successful mission. The paper will detail the importance of the concept of independent checking - that validation must be separate from generation, whether manual or automated. We will also discuss the balance between delivery validation of a system that will produce ground and space commanding products and the continued validation of products that system produces even after acceptance. Not only is this continued verification valuable and critical in a complex operations environment but it is also very important to eliminate sources of error not covered by delivery validation, including human error and the use of the system beyond its original design purpose. Through all of these factors this paper will present the routine operations practice on Mars Express of constant validation of products and how this has ensured that such a complex mission can be conducted safely and efficiently.