Why astronauts quarantine before launch

Uploaded on January 23, 2026

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Why astronauts quarantine before launch

Dr. Raffi Kuyumjian, Flight Surgeon at the Canadian Space Agency – aka the space doctor – answers 10 frequently asked questions about the quarantine period that astronauts need to go through before launching to space. (Credits: Canadian Space Agency, NASA)

Before going to space, astronauts go through a quarantine period. But what does that mean?

The quarantine period is a period of time that is just before a launch where we isolate the crew so that we make sure they're not catching any infectious diseases.

We want to make sure they're not sick before they go into their flight, because they will be in a closed environment for a certain period of time. And viruses can spread easily amongst the crew. So we put them in quarantine, just like we were during COVID times, so that they don't get sick.

We choose to isolate the crew for 14 days before a launch because most infectious diseases take 10 to 14 days to be transferred from one person to another.

Do they need to re-enter quarantine if the launch is delayed?

Well, that depends how long the delay is. If it's a one or two or three-day delay, and if the crew is already on the rocket and they have come back to the quarantine facility, they simply continue the quarantine. However, if the launch is delayed by, let's say, several weeks or a month or more, then they get out of quarantine.

But we have to get back into quarantine two weeks before the next launch attempt. 

Has any astronaut ever gotten sick soon after launch, despite the quarantine?

It has happened, but it's quite rare. Luckily, the few times it has happened before, it was due to respiratory viruses that were not very severe. So the crew did well, and it didn't affect the mission.

Does anyone else go into quarantine with the astronauts?

Usually medical support personnel, crew support personnel, technicians who need to work closely with the crew, they enter quarantine with them so that they don't get sick either.

The quarantine takes place in the astronaut’s home if they elect to do that. There's a quarantine facility at the Johnson Space Center where they start quarantine two weeks before and then a week before launch, they move to the Kennedy Space Center astronaut crew facilities there.

What do they do during that period?

They continue training, but mostly they try to rest, to recover from all the intense training they have done over the last couple of years. They need to be well rested because the mission will be very busy. They go through their last checklist, and they have briefings with the flight directors, and they have their last medical test before they launch.

And they also spend some time with their families.

What else is done to prevent the crew from falling ill?

We test them when we enter quarantine and just before launch. But of course, the most important thing that they do to help them out is not getting any, infectious disease, is get vaccinations against the flu and against COVID, for example. Those are things we take care of as well, not only the crew, but also all the support personnel getting into the quarantine.

What happens if a crewmember falls ill just before launch?

It depends what illness it is. If it's something that is not very severe, it doesn't really affect the launch. If it's something more severe, the flight directors and the managers may elect to delay the launch or replace the crew, which happens extremely rarely.

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