Mission Assurance's independent assessments started during the SPITZER development cycle and continued through post-launch operations. During the operations phase, the health and safety of the observatory is of utmost importance. Therefore, Mission Assurance must ensure requirements compliance and focus on the process improvements required across the operational systems, including new/modified products, tools, and procedures. To avoid problem reoccurrences, an interactive model involving three areas was deployed: Team Member Interaction, Root Cause Analysis Practices, and Risk Assessment. In applying this model, a metric-based measurement process was found to have the most significant benefit. Considering a combination of root cause analysis and risk approaches allows project engineers to the ability to prioritize and quantify their corrective actions based on a well-defined set of root cause definitions (i.e., closure criteria for problem reports), success criteria, and risk rating definitions.