Navigation analysis is performed to aid mission design and to verify the veracity of the navigation system. The latter can be separated into three time-ordered phases being pre-flight, during mission operations, and post-flight. Pre-flight analysis is probably the most important. It involves imagining problems that the navigation system could have during flight and determining the performance of the proposed navigation system. These problems are resolved, and the spacecraft and navigation system design can be modified as appropriate. After launch, it is too late to alter the spacecraft design. During mission operations, the spacecraft is generally in the cruise mode for long periods of time. Navigation analysis continues as before launch with an emphasis on navigation operations. There is not much interest in discovering during cruise that the spacecraft design cannot achieve mission success. During mission operations, a computer solution that takes a week to implement will probably be too late. Post-flight analysis could be useful for problems that may arise during future mission operations. However, funds are generally not available if the mission was determined to be a success.