Commander Jim Lovell saw something disturbing, telling Houston:
“We are venting something out into the — into space. It’s a gas of some sort!”
The gas was oxygen, used to produced air, water, and to power the rocket engines.
With the command module having 417 knobs, levers, switches, selectors and buttons, it took 15 minutes to isolate the problem.
Mission Control, led by flight director Gene Kranz, eventually identified that an exposed wire in an oxygen tank ignited an explosion, irreparably damaging the craft.
In the next two hours, all on-board oxygen was lost, which disabled the hydrogen fuel cells that provided electrical power.
Temporary battery power, oxygen and propulsion was provided by the lunar landing module, which acted as a life boat.
The crew of Apollo 13, Jim Lovell, Jack Swigert and Fred Haise, faced life-threatening conditions as carbon dioxide levels were rising and poisoning the air.
Following Houston's instructions, and using what they had on board, the crew pieced together a carbon dioxide filter, called a scrubber, using a piece of cardboard, a plastic bag, a hose from a pressure suit, duct tape and a sock to connect to the command module scrubbers.
With the only remaining power source being three re-entry batteries intended for use during the last two hours of the mission, power had to be cut back so there would be enough to restart the engines for reentry.
For 90 hours, the astronauts shivered in the dark in temperatures equivalent to a refrigerator.
They had to go to one-fifth water rations, with each astronaut receiving only six ounces of water per day.
The Apollo 13 crew had to manually adjust their flight trajectory to swing around the moon, and head over 200,000 miles back to Earth.
The most complicated part of this was a five-minute engine burn that would give them just enough speed before it ran out of fuel.
After rounding the moon, they had to make one more adjustment, using the sun as an alignment point, then firing the lunar module's small descent engine.
Flight director Gene Kranz refused to give up, with his attitude being described as: “Failure is not an option.”
in New York City's Times Square,
at Chicago's Board of Trade,
at the Wailing Wall in Jerusalem, and
in St. Peter's Square where the Pope led 50,000 people in prayer for the astronauts safe return.
President Richard Nixon asked the nation observe a Day of Prayer.
The New York Times reported, April 15, 1970, "Plight of 3 Apollo 13 Crewmen Stirs World Interest":
"In the United States there was an outpouring of prayer ...
... The Senate and House passed resolutions yesterday asking all Americans to pray, at 9 o'clock Eastern standard time last night, for the safe return of their countrymen ...
and ... urged businesses and communications media to pause ... for the prayers at that hour.
... Special services and masses were called for in thousands of churches and synagogues around the country -- at St. Patrick's Cathedral and St. Thomas Episcopal Church and Temple Emanu-el in New York City ...
... Rabbi Abraham Gross, president of the Rabbinical Alliance of America, called on all clergymen to pray for the safe return of Apollo 13 ...
... In Baltimore, Frank Gunter Jr., Maryland chairman of the National Conference of Christians and Jews, asked all residents of the state to observe a minute of silent prayer at 4 P.M. yesterday ...
... At West Point, N.Y., where the Empire National Bank was holding its stockholders meeting in the Hotel Thayer, the session was closed with a prayer for the astronauts ..."
The New York Times continued, April 15, 1970:
'Oh, God, I hope they return safely,' a woman in the streets of Budapest said ...
Everywhere, people prayed.
... In the Vatican, Pope Paul offered prayers for the safe return of the three men.
Thousands of people of all faiths flocked to churches in Georgetown, Guyana, to pray ...
And in Cheshire County, N.H., in the southwest corner of the state, at noon yesterday, all the church bells pealed."
TV newsman Walter Cronkite reported:
"Perhaps never in human history has the entire world been so united by such a global drama."
In 1995, Ron Howard produced the movie Apollo 13, based on Jim Lovell's novel Lost Moon, starring Tom Hanks, Kevin Bacon, Bill Paxton, Gary Sinise, Kathleen Quinlan, Ed Harris, Loren Dean, and Clint Howard.
During the time of freezing temperature, moisture from their breath froze on the inside of the spacecraft.
In preparing for reentry, the astronauts restarted the command module and the temperature rose, causing the water to rain down on the electrical panel.
Thankfully, none of the switches short-circuited.
After jettisoning the lunar module and service module, Jim Lovell looked out his window at them and exclaimed to Mission Control:
“There’s one whole side of that spacecraft missing!”
Not knowing if the explosion had also damaged the reentry capsule's heat shield, they were apprehensive that they might burn up upon entering Earth's atmosphere.
They manually steered the capsule to land in the ocean, avoiding a raging hurricane.
As they approached the period of reentry when there is a communication blackout, Swigert gave a farewell to Houston, saying:
“I know all of us here want to thank all you guys down there for the very fine job you did!”
The blackout began, and everyone at Mission Control held their breath, counting the seconds.
After an entire minute passed when they should have reestablished contact, Kranz said,
“A sinking feeling, almost a dread, filled the room.”
Finally, a minute and 28 seconds late, they heard Swigert's voice.
After the successful landing, April 19, 1970, TIME Magazine's cover photo showed the crew on the deck of the aircraft carrier with their heads bowed in prayer.
President Richard Nixon spoke at Kawaiahao Church, one of the oldest Christian Church in Hawaii:
"When we learned of the safe return of our astronauts, I asked that the Nation observe a National Day of Prayer and Thanksgiving today ..."
"This event reminded us that in these days of growing materialism, deep down there is still a great religious faith in this Nation ...
... I think more people prayed last week than perhaps have prayed in many years in this country ...
We pray for the assistance of God when ... faced with ... great potential tragedy."