Awkward and angular looking, Apollo 17's lunar module, dubbed Challenger, was designed for flight in the vacuum of space. This picture, taken from the America command module, shows Challenger's ascent stage in lunar orbit. This spaceship performed gracefully, landing on the moon on Dec. 11, 1972. Forty years later, the descent stage remains at Apollo 17's lunar landing site. The ascent stage, however, was jettisoned from the command module prior to the return to Earth - and crashed onto the lunar surface.