The intended mission was to effect the third soft landing on the moon, but the landing was aborted because of systems failure. At 55 hours 55 minutes into the mission, after a trouble-plagued launch, an electrical short circuit caused an explosion and fire in the Service Module that resulted in failure of the spacecraft's number two oxygen tank and loss of most of the electrical power in the Command Module. At 61 hours 30 minutes, the spacecraft had reached the moon and effected a mid-course maneuver by firing the LM's descent engine to put it on a return-to-earth trajectory. Although the life support system of the CM was damaged, there was just enough oxygen available in the LM Aquarius to use it as a 'lifeboat' to get the crew back to earth safely, where they splashed down in the Pacific.