In the early days of space exploration when a flight component failed the mission was over. In recent history, there have been a few times when astronauts have repaired satellites and a number of instances of Earth bound engineers reprogramming malfunctioning spacecraft so that they could continue their scientific work. Since the cost of developing and launching spacecraft far exceeds the cost of operating them for extended periods of time, our ability to recover from malfunctions allows scientists to make the best use of available funds.