Probabilistic Risk Assessment: A Practical & Cost Effective Approach

This paper describes the approach taken for the reliability analyses, including probabilistic risk assessments (PRAs), of the Lunar Reconnaissance Orbiter (LRO) that have been performed concurrently with the designs to identify problem areas and ensure corrective actions were taken in a timely manner. The LRO is a large system with more than 14,000 piece-parts and over 120 purchased or contractor-built components. These analyses formulate the probability of failure for each of the components of the system. PRA then integrates these analytical techniques and results to assess the potential for failure and to help find ways to reduce the mission risks. By utilizing the traditional and innovative methods to perform reliability analyses, such as reliability predictions, failure modes and effects analysis (FMEA), and fault tree analysis (FTA), the LRO project office, with close collaboration with the reliability team, has improved the probability of mission success, from 0.72 to 0.81, within a tight schedule and limited budget. As more data from the manufacturers and GSFC designs become available, the reliability and system teams will continue to update the analyses to assess risks throughout the entire lifecycle of the mission