The world rejoiced when Apollo 11 astronauts Neil Armstrong, Buzz Aldrin and Michael Collins safely splashed down in the Pacific Ocean on July 24, 1969, after their incredible journey to the Moon.

Plucked from the ocean by helicopters from the USS Hornet, the three astronauts were given a hero’s welcome by President Richard Nixon, who had been anxiously awaiting their return aboard the aircraft carrier.

For Armstrong, Aldrin and Collins, however, their return from the Moon still represented a step into the unknown.

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Scientists were concerned that the crewmembers may have brought pathogens back from the Moon with them, so they immediately entered a Mobile Quarantine Facility (MQF), a converted Airstream trailer that was waiting for them on the USS Hornet.

The MQF containing the astronauts was lifted off the USS Hornet when it reached Pearl Harbor and then transferred to Hickam Air Force Base, where it was loaded onto an Air Force C-141 jet transport and flown to Ellington Air Force Base in Houston. From there, the astronauts were taken to the more spacious confines of the Lunar Receiving Laboratory at Johnson Space Center. But they were still very much in quarantine.

In addition to NASA personnel, the astronauts also had a large group of rodent room-mates at the Lunar Receiving Laboratory, who were carefully monitored for signs of any germs brought back from the Moon.

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“We had a huge colony of white mice,” Collins told Fox News. “The three of us had gone to the Moon – that was either a national, international, triumph, or it was a total disaster depending on the health of the white mice that we had.”

“If the mice lived, everything was fine,” he added.

After traveling hundreds of thousands of miles to and from the Moon, the trio of astronauts were now going nowhere, at least for a while.

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“Although all three astronauts were veterans of prior missions, none had ever spent so much time in space, and post-mission activities had never been conducted under strict confinement,” notes NASA’s history office. “Thus quarantine quickly became oppressive, the more so because only meager provision had been made for recreation. An exercise room was available, as well as a Ping-Pong table, and they could read or watch television or talk by telephone to their families, but it was not like being at home.”

Less than a week after their return from space, NASA asked the astronauts how their time in the receiving laboratory was going. Armstrong’s “noncommittal” response was that, so far, it had been going "about as well as you can expect." Collins, understandably, said “I want out,” according to the space agency’s history office.

Fortunately, the colony of mice did not display any ill effects and the astronauts were finally released from quarantine on Aug. 10, 1969.

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Half a century later, Collins, now a sprightly 88-year-old, told Fox News that the quarantine period “was a piece of cake.”

The astronaut’s choice of reading matter in quarantine was particularly apt. “At the time, I was reading a book by John Steinbeck - ‘Of Mice and Men’,” he said, with a smile.

Collins spoke to Fox News in New York on Sunday after taking part in “One Giant Leap,” an event organized by the New York Times to commemorate the Moon landing.

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July 20, 2019, marked the 50th anniversary of the Moon landing when Armstrong and Aldrin became the first humans to set foot on the lunar surface. While his crewmates were exploring the Moon, Collins was piloting the Columbia Command Module, which was orbiting 60 miles above them.

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The MQF used by the Apollo 11 astronauts is now in the collection of the Smithsonian National Air and Space Museum.

Follow James Rogers on Twitter @jamesjrogers