Moon bugs: astronauts under quarantine

On Earth, quarantines help to contain outbreaks. During the Apollo Missions, NASA took precautions to make sure no alien germs hitched a ride back to Earth.

Illustration by Lucas Peverill

Illustration by Lucas Peverill

Buzz Aldrin, the second man to walk on the Moon, described the atmosphere of the lunar surface as magnificent desolation. It’s difficult to imagine a more palpable sense of isolation than being out in space, far away from everything you know. However, for the three astronauts who formed the Apollo 11 mission to the Moon in 1969, their separation from humanity lasted much longer than the eight days they spent in space. To prevent the spread of any possible celestial diseases, Neil Armstrong, Buzz Aldrin, and Michael Collins spent three weeks under heavily-monitored quarantine. Richard Nixon greeted them on their return to Earth through a thick sheet of glass, congratulating them on their success while keeping a healthy distance.  

An epidemic or a plague is an easy topic for a disaster movie. We are instinctively afraid of diseases; they’re unseen, deadly, and hard to control. In a time where millions of passengers cross international borders every day, modern public health measures are important to prevent the next bubonic plague. One such measure is quarantining, where we isolate people who might be infected in order to prevent the spread of disease.

Quarantine can involve a number of measures, but it usually involves restricting someone’s movements (such as keeping them contained in a particular facility) and monitoring for signs of disease. There is a difference between isolation, used when someone is already infected, and quarantine, used when someone appears healthy but might be infected, such as when they have travelled from some region with active infection in the population.

In 1969, US President Richard Nixon greets the Apollo 11 crew, who have just returned from the Moon.   NASA/Wikimedia Commons  (public domain)

In 1969, US President Richard Nixon greets the Apollo 11 crew, who have just returned from the Moon. NASA/Wikimedia Commons (public domain)


During the space race, the US and Soviet Union governments and scientific communities were concerned that forays into outer space might bring back unwelcome passengers. A US government working group set up within the National Academy of Sciences (NAS) in the early 1960s advised that “the introduction into the Earth's biosphere of destructive alien organisms could be a disaster… We can conceive of no more tragically ironic consequence of our search for extraterrestrial life.”

These concerns spilled over into popular culture. When we think of alien invaders, it’s not just armies we fear, but stealthy pathological entities infecting us from the inside out. Classic sci-fi horror films such as The Thing (1982) or Invasion of the Body Snatchers (1956) draw on this dread. They feature parasites that invade or assimilate our bodies, both killing and transforming us into something horrific. Unknown lifeforms and possible diseases from outer space that we cannot possibly combat, like the Andromeda Strain (1969), are a frightening prospect.

Although the competition to reach the heights of the cosmos was fierce, participants in the space race agreed upon certain rules of play. In 1967, the United Nations passed the Outer Space Treaty, which outlined all the ways in which nations are allowed, and not allowed, to explore and use space. This treaty recognised contamination, in both directions, as a serious risk. Article IX of the treaty directs nations venturing into space to avoid contaminating the celestial bodies that they might explore. Just as importantly, it calls for preventing environmental catastrophe on Earth that might result from the introduction of extraterrestrial matter. The international Committee on Space Research (COSPAR), established in 1958, also has guidelines for planetary protection that influenced NASA’s approach.

The US had already been working on this problem. In 1963, the NAS recommended that NASA quarantine any astronauts coming back from lunar landing missions. Although the risk of a space contagion was low, it was a possibility that couldn’t be gambled with. There was so little information about what such a contagion might look like that NASA had to be cautious; the result of a misstep could be disastrous.

The Apollo 11 mission landed two men on the Moon on 20 July 1969. They collected a number of samples from the lunar surface and left behind an American flag, which ended up toppling over. However, the trouble was not just to get the astronauts to the Moon, but also how to get them back to Earth without harm. The speechwriters for the president prepared for the eventuality of the astronauts being stranded on the Moon. Fortunately, the president did not have to use this speech. After more than a week in space, the astronauts safely returned to Earth on 24 July, landing in the Pacific Ocean near Hawaii.  

When the command module splashed down, the aircraft carrier USS Hornet was there to meet it. Before the astronauts left the module, the retrieval team gave them biological isolation garments to wear. These were effectively large cotton suits with respirators designed to keep any biological contaminants contained. The three wiped themselves down with sodium hypochlorite, and when specialists retrieved the command module, they wiped it down with antiseptic to ensure the sterilisation of any remaining lunar dust. Upon donning the containment suits, the astronauts were winched onto a helicopter and delivered to the USS Hornet.

NASA converted four Airstream caravans to serve as Mobile Quarantine Facilities. Later versions of the Airstream caravan would transport astronauts during NASA’s shuttle program.   Cliff/Flickr  (CC BY 2.0)

NASA converted four Airstream caravans to serve as Mobile Quarantine Facilities. Later versions of the Airstream caravan would transport astronauts during NASA’s shuttle program. Cliff/Flickr (CC BY 2.0)


Waiting for them on the ship was the Mobile Quarantine Facility. The MQF, which was one of four NASA made for Apollo missions, was an alteration of an iconic caravan, the Airstream. Composed of curved aluminium and hermetically sealed, this space-age design was fitting to welcome three people who had made one of the most significant space travel achievements of the 20th century. At 11 metres long, the MQF was designed to temporarily house the astronauts as they travelled from their recovery point in the Pacific Ocean to Houston. A doctor and an engineer joined them in quarantine. NASA loaded the MQF onto a plane, with everyone inside, and flew it straight to Houston.

The designers of the MQF built it to hold six people for up to ten days, and it had a lounge, toilets, and sleeping facilities. It was also equipped with what was, at the time, a very novel appliance — the microwave oven. Special meals in sterile containers could be heated up in the microwave.

Negative pressure ensured that no contaminants inside the MQF could escape. Negative pressure is achieved by making the room or facility airtight, and then pumping (and filtering) more air out than comes in. This creates a pressure gradient that means air passively flows in, but can’t get out.

Upon reaching Houston, the three astronauts transferred to the Lunar Receiving Laboratory (LRL), where they spent another couple of weeks in much more spacious quarantine quarters. Compared to the MQF, the LRL was sprawling, taking up a large building in the NASA complex. The astronauts were finally able to isolate themselves from each other; the LRL had bedrooms, a living room, offices, and medical facilities.

In the LRL, the astronauts underwent daily medical examinations. It was important to make sure that the three men — particularly the two who had walked on the lunar surface — did not fall prey to any extraterrestrial disease. However, NASA did not value quarantine over the risk to life in the event of an illness; in the event of an astronaut falling seriously ill, they would be transported to an appropriate medical facility.

The LRL also quarantined the samples that were brought back from the lunar surface. It was essential that no organisms from Earth could contaminate them, as this would have wreaked havoc with any scientific findings. Indeed, species of a common bacteria was found on a camera used during the later Apollo 12 mission, sparking talk that they might have survived the vacuum of space. However, later analyses determined that it was more likely to have been contamination in the lab.

Today, NASA no longer quarantines astronauts after missions. After the Apollo missions, the relevant committee determined the Moon to be sterile through exhaustive studies, including injecting lunar material into plant and animal test subjects. There appeared to be little risk of lunar disease to justify continuing post-mission quarantine. However, astronauts are still quarantined in crew quarters in the days leading up to the mission, to ensure that nobody gets sick while in space.

It’s not difficult to see why the astronauts who landed on the Moon would consent to quarantine upon their return. They were prepared to face the risks. Their time spent in quarantine was expected, comfortable, expensed, and part of their job description.

The Apollo 12 crew also spent time in a Mobile Quarantine Unit after their return from the Moon.   NASA/Wikimedia Commons  (public domain)

The Apollo 12 crew also spent time in a Mobile Quarantine Unit after their return from the Moon. NASA/Wikimedia Commons (public domain)


Photos from their time in quarantine show them relaxing and reading the news. In Buzz Aldrin’s autobiography, No Dream Is Too High, he said: “The unit was comfortable, but there was little to do and nowhere to go, so we got bored in a hurry.”  Although spending weeks in isolation is not necessarily pleasant, it was a reasonable precaution for NASA to take. Who knows what germs there are in space?

The manned mission to the Moon was a special case. Quarantining the astronauts made sense, and it didn’t hurt them. However, other cases of quarantine are not always so clear-cut. The more common use of quarantine — dealing with all-too-existing diseases here on earth — presents more complex ethical issues than post-Moon quarantine. There’s a lot of things to consider.

Sometimes, quarantine involves detaining someone without giving them a choice in the matter — even if it is against their will. What these situations involve are the limitation of someone’s autonomy, which should only be done when there is very good reason to do so — such as the risk of harm to other persons. “Justification of quarantine and quarantine laws stems from a general moral obligation to prevent harm to (infection of) others if this can be done,” writes bioethicist Ross Upshur of the University of Toronto.

There are generally legal bases for quarantine. Authorities concerned with public health, such as the Centers for Disease Control and Prevention in the US or the Department of Health in Australia, have the ability to enact and enforce quarantine orders on individuals. Failure to cooperate can be considered a crime. In Australia, strict biosecurity laws mean that quarantine is regularly enforced at its borders.

A US public health poster circa 1910 warns against approaching a house where people with diptheria infections live.   U.S. National Library of Medicine  (public domain)

A US public health poster circa 1910 warns against approaching a house where people with diptheria infections live. U.S. National Library of Medicine (public domain)


Limiting someone’s autonomy isn’t something to be done lightly. There are a number of important things to consider when assessing how valid it is to restrict someone’s autonomy, as in the case of quarantine. This includes the need for a clear, evidence-based possibility of harm.

Much of the panic around AIDS patients in the 1980s that led to unnecessary isolation and social stigmatisation stemmed from a risk of harm that had no basis in fact. Healthcare workers would refuse to touch AIDS patients and children with the disease had to fight to be allowed to attend school. We know now that the risk of transmission was greatly overestimated in the minds of the public at the time; 50% of American adults in one survey thought AIDS patients should be quarantined.

People with suitcases arrive at the Wallangarra Quarantine Camp during the Spanish Flu epidemic in 1919 .  State Library of Queensland/Flickr  (No known copyright restrictions)

People with suitcases arrive at the Wallangarra Quarantine Camp during the Spanish Flu epidemic in 1919. State Library of Queensland/Flickr (No known copyright restrictions)


Ethicists say that quarantine should be equally applied, otherwise it runs the risk of targeting vulnerable populations. “The use of segregation or isolation to separate persons suspected of being infected has frequently violated the liberty of outwardly healthy persons,” says researcher Eugenia Tognotti. For these reasons and more, authorities need to be accountable for any quarantine measures they enact.

Often, there are concerns that applications of quarantine and isolation are discriminatory. For example, US authorities unfairly quarantined Chinese-Americans in San Francisco in the early 20th century. Several cases of the plague had hit San Francisco, and Chinatown was quarantined, preventing the movement of Chinese-Americans while white people were free to walk in and out of the area without being detained.

Bioethicists such as Upshur say that reciprocity is also an important consideration. Because someone in quarantine is generally there for the benefit of others, it is important that those who are quarantined receive some benefits such as food, shelter, and easy access to medical care that they might need. They might also be first in line to receive any treatment that is developed while they are in quarantine.

The method of quarantine used should be least restrictive, interfering with daily life as little as possible. Ideally, quarantine should be voluntary, and mandatory measures should be reserved for last resort. The reason for it should be clearly and transparently communicated — to the public, and especially to the person in quarantine.

Although it is no longer required for astronauts, quarantine for space exploration might be coming back as a priority. In 2018, NAS released another report recommending that the quarantine procedures for the next frontier — Mars — be re-evaluated. It’s especially important when we consider that it’s no longer just governments sending people into space. Private companies might feel less inclined to play by cautious rules. As we progress further and further into outer space, to Mars and beyond, we will need to decide where to draw the line on quarantine.

Edited by Diana Crow.