Trial and error was the name of the game for these unmanned 1960s space missions, intended to provide NASA with the first close-up images of the moon's surface. Early on it was mostly errors. Each spacecraft was stocked with six cameras designed to transmit photos until the Ranger collided with the lunar surface. Things didn't exactly go as planned. Ranger 1 sent up in August 1961 failed to launch. So did Ranger 2 three months later. The third try, launched in January 1962, managed to get into space only to miss the moon entirely. Attempt No. 4 in April the same year launched flawlessly, but the ship itself proved faulty. Ranger 5 launched fine in October but, like its earlier cousin, missed the moon. Ranger 6 came closer than any of its predecessors: the ship impacted the moon as it was meant to, but an accident during flight messed up the cameras and it couldn't snap any shots. Finally, Ranger 7, launched in July 1964, managed to hit the moon, sending more than 4,300 pictures to scientists who must have been relieved. Seventh time's a charm.
Next Mars Climate Orbiter