ON THIS DAY

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April 13, 1970

Apollo 13 announces "Okay, Houston, we've had a problem here".

Apollo 13 (April 11–17, 1970) was the seventh crewed mission in the Apollo space program and would have been the third Moon landing. The landing was aborted after an oxygen tank in the service module (SM) exploded two days into the mission, on April 13, disabling its electrical and life-support system and causing Swigert to report "Okay, Houston, we've had a problem here,"

The crew, supported by backup systems on the lunar module (LM), instead looped around the Moon in a circumlunar trajectory and returned safely to Earth on April 17. The mission was commanded by Jim Lovell, with Jack Swigert as command module (CM) pilot and Fred Haise as Lunar Module (LM) pilot.

A routine stir of an oxygen tank ignited damaged wire insulation inside it, causing an explosion that vented the contents of both of the SM's oxygen tanks to space. Without oxygen, needed for breathing and for generating electric power, the SM's propulsion and life support systems could not operate. The CM's systems had to be shut down to conserve its remaining resources for reentry, forcing the crew to transfer to the LM as a lifeboat. With the lunar landing canceled, mission controllers worked to bring the crew home alive.

Although the LM was designed to support two men on the lunar surface for two days, Mission Control in Houston improvised new procedures so it could support three men for four days. The crew experienced great hardship, caused by limited power, a chilly and wet cabin and a shortage of potable water. There was a critical need to adapt the CM's cartridges for the carbon dioxide scrubber system to work in the LM; the crew and mission controllers were successful in improvising a solution. The astronauts' peril briefly renewed public interest in the Apollo program; tens of millions watched the splashdown in the South Pacific Ocean on television.

An investigative review board found fault with preflight testing of the oxygen tank and Teflon being placed inside it. The board recommended changes, including minimizing the use of potentially combustible items inside the tank; this was done for Apollo 14.

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