Few endeavors are as technologically demanding as the design and operation of rockets and robotic spacecraft. A deep space mission is a lengthy sequence of critical events, all of which must be achieved, either in a straightforward manner or by a work around. For example, the Cassini-Huygens mission must survive in space for seven years, flying a precise course, simply to reach its target, Saturn. It could all too easily suffer an irrecoverable failure at any stage. In fact, throughout the "Space Age" a range of systems failures has frustrated missions. These have included total booster malfunction, by rocket upper stages failing to ignite or misfiring, by being stranded in parking orbit around the Earth, by being sent on the wrong trajectory, by loss of control during mid-course correction maneuvers, by failure to deploy their communication antennas, by missing their targets completely, by crash landing, and by instrumentation failures.