On 24th July 1969, at 16:50 UTC, Apollo 11 splashed down in the north Pacific, about 900 miles south west of Hawaii.

Worried about bringing back potentially harmful pathogens from the Moon, NASA had made arrangements for the astronauts to spend 21 days in quarantine. Navy divers gave them special isolation suits, which they put on in the capsule and wore during their relocation onto the aircraft carrier USS Hornet. Once onboard, they were ushered into a special isolation chamber – the Mobile Quarantine Facility (MQF), a modified Airstream trailer. Inside the trailer they were free to move around as they pleased, they could take a shower and heat up meals in an early domestic-scale microwave. They could see their relatives through the glass, and speak to people outside via microphones. Compared to the cramped conditions of Apollo 11, it was almost a paradise.

President Nixon welcoming the quarantined Apollo 11 astronauts back to Earth
[Image credit: NASA]

The Airstream was a temporary measure, in any case. The USS Hornet docked in Pearl Harbor, and the MQF (astronauts included) was taken to Hickam Air Force Base, and onto an Air Force jet for the flight to Ellington Air Force Base in Houston. From there it was taken to the Lunar Receiving Laboratory at Johnson Space Center, where the astronauts could disembark into more spacious quarantine quarters, where they finally got their own rooms. They also had some rodent room-mates who were in charge of detecting (by getting sick, or not) any noxious germs.

[It’s not true that the astronauts went through customs in Hawaii, declaring their moon rock and dust samples. Although an official-looking document exists that suggests they did, it’s is a commemorative one, created weeks after the landing.]

An MQF was also used for Apollo 12 and 14, and would have been used for  Apollo 13 had it landed on the Moon. Having found no evidence of lunar-microorganisms, NASA retired the MQF. Of the four originally built, three are now in museums, and the fourth found service with the US Department of Agriculture, and its location is currently unknown. There are some lovely photos of the one that’s on display at the National Air and Space Museum.

The Apollo 11 astronauts relaxing in their MQF
[Image Credit: NASA]

It all sounds tickety-boo, and very scientific, but in recent interviews both surviving Apollo 11 astronauts noted that the quarantine procedures fell down right at the start. As Michael Collins pointed out, as soon as the capsule hatch was opened, any microbes would have been able to escape into the air. And Buzz Aldrin has admitted that after the Navy divers wiped him down with a cloth, they disposed of it by dropping it into the ocean….

Meanwhile, the Columbia module was hosed down with the anti-infective liquid Betadine. I wonder what they did with the dirty water? Oh, and the raft and equipment that had been used to decontaminate the astronauts while they were in the water was then simply dismantled… and sunk.

Apollo 11 splashdown
[Image credit: NASA]

By modern standards, NASA’s 1969 quarantine procedures wouldn’t cut the mustard, but no doubt they were doing their best at the time. They were governed by the 1967 UN Outer Space Treaty, which recognised contamination, in both directions, as a serious risk. Spacefaring nations were called upon to avoid a potential environmental catastrophe by bringing space microbes back to Earth; they were also called upon to avoid contaminating the celestial bodies that they might explore. (So how did NASA got away with leaving so much stuff on the Moon, including human wastes? That kind of behaviour isn’t allowed in Antarctica, for example.)

During the Apollo 12 mission, astronauts collected equipment – including a camera – from the Surveyor 3 probe that had landed on the Moon in April 1967. They returned it to Earth, where it was examined in a clean room. The scientists there found a small colony of common bacteria – Streptococcus mitis – on the device. There was no question that those bacteria had come from the Moon; they were a species commonly found in the human respiratory system. NASA assumed they had been on the spacecraft when it left Earth, as it hadn’t been sterilised before launch, and had then survived 2.5 years on the Moon.

Apollo 12 Visits Surveyor 3
[Image credit: Apollo 12 Crew/NASA]

The story caught the public’s imagination, and has resurfaced many times since then, to the point where John Rummel, a professor of biology at East Carolina University, felt compelled to write a paper re-examining and thoroughly debunking that theory. What he found was that the clean room conditions under which the camera had been examined were anything but sterile, and the bacteria had found their way onto it from one of the scientists. He notes that out of 32 samples taken, only one came back positive for microbes of any kind.

Still, it wasn’t long after the Apollo missions that we discovered the existence of extremophiles, organisms (bacteria and viruses, mainly) that can thrive in conditions that we originally thought could not harbour life. We know that the upper atmosphere is dry, rife with UV radiation and devoid of nutrients, and yet thousands of microbial species have been found in the upper atmosphere, where they can travel thousands of kilometres in atmospheric eddies. Microorganisms may not be able to live in those conditions, but they can survive in a form of stasis, and reactivate on their return to Earth.

There have been studies that exposed various forms of life to space conditions, latched onto the outside of the International Space Station, and some of them survived for up to 18 months. In 2017, scientists found an “aggressive space fungus” growing on the OUTSIDE of the Mir space station, leading to NASA starting to see space fungi as a serious issue. On the other hand, there are scientists who think that a fungus that feeds on ionising radiation is just the kind of thing we need to provide an inexhaustible supply of food in space. Yum.

Inside a space station it’s much more cosy, of course. In 1998, US astronauts visiting Mir collecting various environmental samples from inside the space station were horrified to find a free-floating mass of water nearly the size of a basketball floating behind a rarely-accessed panel. Not only was it huge, but it was also filthy, and it was not the only nasty globule hiding away. Samples returned to Earth were found to contain several dozen species of bacteria and fungi.

In April 2019, NASA published the results of a microbial study of the inside of the space station. What they found was a collection of microorganisms associated with humans, some of which are known to cause disease, and some of which form pesky biofilms that can be hard to remove. This basically confirms an early study which found the ISS contains similar microorganisms to a house; we take our microbiomes with us when we travel, and there’s some evidence that they’re adapting to live in microgravity. Crews on the ISS spend their Saturday mornings cleaning, to keep the place nice and clean; even an astronaut can’t escape the chores.