Luna 6It’s not easy to reach the moon. Just a month after the failed flight of Luna 5, the Soviet Union launches the near-identical unmanned spacecraft Luna 6 to the moon. A pre-programmed mid-course correction engine burn, meant to help Luna 6 coast toward a soft landing on the lunar surface, instead overcorrects. The engine fails to acknowledge a command to stop firing, pushing Luna 6 so far off course that it misses the moon by almost 100,000 miles, dumping the vehicle in an orbit around the sun.