Description: Apollo 13 was the third American manned lunar landing mission, part of the Apollo program. Two days after launch, the Apollo Spacecraft was crippled by an explosion, causing the Service Module portion of the Apollo Command/Service Module to lose its oxygen and electrical power. The crew used the Lunar Module as a lifeboat in space. The command module systems remained functional but were deactivated to preserve its capability to re-enter earth's atmosphere upon return to the earth. The crew endured difficult conditions due to severe constraints on power, cabin heat, and drinkable water, but successfully returned to Earth.