The shuttle’s flexibility was ironically its biggest downfall. Unlike previous spacecraft designs for Mercury, Gemini, and Apollo—in which the capsule with the astronauts was at the front end of the rocket—the space shuttle and its crew rode into orbit beside the propellant tank and the rocket boosters. This meant that ice or other debris could fall off the tank and boosters and strike the shuttle during ascent. Damage from launch debris was one of NASA’s major headaches, as there was no way to repair an orbiter’s exterior surfaces once the vehicle reached orbit.
