NASA Astronauts Eugene Cernan and Harrison Schmitt explored the surface of the moon during the Apollo 17 mission in 1972, the last time anyone has left earth's orbit or set foot on the moon.  During a 40th anniversary celebration of Apollo 17 in Chicago, the astronauts said they had expected their mission would  start a path toward space travel, not become a history lesson. Retired Astronaut Eugene Cernan is one of just twelve men who walked on the moon.  He currently holds ...