Apollo 13 was NASA’s third moon-landing mission but didn’t reach the lunar surface. A series of problems plagued the Odyssey spacecraft which was designed to bring them home, causing the crew to abandon all thoughts of reaching the moon.

A fire ripped through one of Odyssey’s oxygen tanks and damaged another. Oxygen fed the fuel cells in the spacecraft, so power was also reduced. Fortunately, the spacecraft Aquarius — designed to land on the moon — was still in working order. But Aquarius didn’t have a heat shield so it would not survive the reentry back to Earth. So, the crew crammed themselves into Aquarius — which was designed for two people, not three — and began the long cold journey home. Without a source of heat, cabin temperatures quickly dropped close to freezing. Some food became inedible. The crew also rationed water to make sure Aquarius — operating for longer than it was designed — would have enough liquid to cool its hardware down.
In the hours before splashdown, the exhausted crew scrambled back over to the Odyssey and powered it up.
Thanks to a monumental effort from the crew, mission control and spacecraft manufacturers helping with the mission, Lovell, Haise and Swigert safely splashed down in the Pacific Ocean near Samoa, on April 17, 1970.

How did Apollo 13 get back to Earth safely?

The Apollo 13 crew used their lunar lander — Aquarius — as a makeshift ‘lifeboat’ to survive the long cold journey back to Earth. It was a rough journey home. The entire spaceflight crew lost weight, and Fred Haise developed a kidney infection. But the small vessel protected and carried the crew long enough to reach Earth’s atmosphere. The crew only returned to Odyssey in the hours before splashdown to power it up and begin their reentry to Earth.
Apollo 13: “Houston, we’ve had a problem”
Apollo 13 launched on April 11, 1970. The Apollo spacecraft was made up of two independent spacecraft joined by a tunnel: orbiter Odyssey, and lander Aquarius. The crew lived in Odyssey on the journey to the moon.

On the evening of April 13, when the crew was nearly 322,000 kilometers (200,000 miles) from Earth and closing in on the moon, mission controller Sy Liebergot saw a low-pressure warning signal on a hydrogen tank in Odyssey.

The signal could have shown a problem, or could have indicated the hydrogen just needed to be resettled by heating and fanning the gas inside the tank. That procedure was called a “cryo stir”, and was supposed to stop the supercold gas from settling into layers.

Swigert flipped the switch for the routine procedure. A moment later, the entire spacecraft shook. Alarm lights lit up in Odyssey and in Mission Control as oxygen pressure fell and power disappeared. The crew notified Mission Control, with Swigert famously saying, “Houston, we’ve had a problem.” (Note that the 1995 movie “Apollo 13” took some creative license with the phrase, changing it to “Houston, we have a problem” and having the words come out of Apollo 13 commander James Lovell’s mouth).

Much later, a NASA accident investigation board determined wires were exposed in the oxygen tank because of a combination of manufacturing and testing errors before flight. That fateful night, a spark from an exposed wire in the oxygen tank caused a fire, ripping apart one oxygen tank and damaging another inside the spacecraft.

Since oxygen fed Odyssey’s fuel cells, power was reduced as well. The spacecraft’s attitude control thrusters, sensing the venting oxygen, tried to stabilize the spacecraft by firing small jets. The system wasn’t very successful given several of the jets were slammed shut by the explosion.

Fortunately for Apollo 13, the damaged Odyssey had a healthy backup: Aquarius, which wasn’t supposed to be turned on until the crew was close to landing on the moon. Haise and Lovell frantically worked to boot Aquarius up in less time than designed. Aquarius didn’t have a heat shield to survive the drop back to Earth, so as Lovell and Haise got the lunar module up and running, Swigert remained in Odyssey to shut down its systems to conserve power for splashdown. 

Apollo 13’s cold, miserable trip home

The crew had to balance the challenge of getting home with the challenge of preserving power on Aquarius. After they performed a crucial burn to point the spacecraft back toward Earth, the crew powered down every nonessential system in the spacecraft.

Without a source of heat, cabin temperatures quickly dropped down close to freezing. Some food became inedible. The crew also rationed water to make sure Aquarius — operating for longer than it was designed — would have enough liquid to cool its hardware down. And Aquarius was pretty cramped as it was designed to hold two people, not three.

On Earth, flight director Gene Kranz pulled his shift of controllers off regular rotation to focus on managing consumables like water and power. Other mission control teams helped the crew with its daily activities. Spacecraft manufacturers worked around the clock to support NASA and the crew.

It was a rough journey home. The entire spaceflight crew lost weight, and Haise developed a kidney infection. But the small vessel protected and carried the crew long enough to reach Earth’s atmosphere.

In the hours before splashdown, the exhausted crew scrambled back over to the Odyssey and powered it up. The craft had essentially been in a cold water soak for days and could have shorted out, but thanks to safeguards put in place after the Apollo 1 disaster, there were no issues. 

Lovell, Haise and Swigert safely splashed down in the Pacific Ocean near Samoa, on April 17.

I found this great site—15 facts—that lists 15 facts on a variety of subjects. Today’s 15 facts are about Thomas Jefferson (in honor of his birthday—born in 1743 and died July 4, 1826).

From 15funfacts.com:

He popularized macaroni and cheese in the United States. He famously brought a pasta machine back from France to satisfy his craving for the dish.

Thomas Jefferson died on July 4, 1826. Remarkably, this was the exact same day that his friend and rival John Adams passed away.

He kept pet mockingbirds in the White House. He loved the birds so much that he often let them fly freely around his office.

He sold his personal collection of 6,487 books to the government. This massive sale effectively restarted the Library of Congress after the British burned the original one.

Surprisingly, he was obsessed with finding living mastodons. He laid out giant fossil bones in the East Room of the White House for guests to see.
He invented the swivel chair. He modified a regular chair with an iron spindle so he could rotate while he worked at his desk.
Thomas Jefferson stood at a height of 6 feet 2 inches (1.89 meters). Therefore, he towered over most other men of his era.
He wrote his own epitaph but left off his presidency. He wanted to be remembered as the author of the Declaration of Independence instead.
He recorded the weather every single day of his adult life. Thus, historians have a perfect record of the temperature in Virginia for decades.
He spent a fortune on wine. In fact, he once ordered 20,000 bottles from France for his personal cellar.

Thomas Jefferson reportedly broke his wrist while trying to impress a woman. He attempted to jump over a fence in Paris but fell awkwardly.

He wrote down the first known recipe for ice cream in America. Specifically, he created a vanilla custard version that became a favorite at his dinner parties.

He designed a “Great Clock” for his home at Monticello. The weights are so long they have to drop through holes in the floor.

Thomas Jefferson could read and write in six different languages. He mastered Greek, Latin, French, Italian, Spanish, and English.

Finally, he introduced the French fry to America. He served “potatoes fried in the raw” at a White House dinner in 1802.

SOURCE: 15FUNFACTS.COM