More than half way to the Moon, Apollo 13 was crippled by an explosion 50 years ago, forcing the astronauts and Mission to scramble to get the crew home safely. From top left: Apollo 13 slides behind the Moon to get a "slingshot" back to Earth; the damaged service module; the crew jettisons the lunar module, Aquarius, which served as a lifeboat for the trip back to Earth; splashdown; astronauts (l-r) Fred Haise, Jack Swigert, and Jim Lovell on the deck of the USS Iwo Jima. [NASA]