With the successful launch of Mars Observer, NASA once again set its sights on the Red Planet, a decade and a half after the successful Viking program. Mars Observer, designed to study the geosciences and climate of Mars, was the first mission of the Planetary Observer series, which was envisioned as a series of low-cost missions to the inner solar system. Unfortunately, it also turned out to be the last. After an eleven month journey through space, NASA lost contact with the spacecraft, only three days before the scheduled orbital insertion. With no physical or telemetry evidence to investigate, the Mission Failure Investigation Board faced a significant challenge. What they eventually learned were valuable lessons in the importance of testing, the potential consequences of making tradeoff decisions and the absolute necessity of a functional risk management process.