As of December 4, 2019, 565 people from 41 countries have gone into space. That’s it. 565 out of more than 7 billion of us currently on this planet. And that’s using the definition of space travel to include any flight over 62 miles or about 100 kilometers.

Many of these space travelers are, of course, NASA astronauts. That means they went through a rigorous application and training process. So, what exactly does it take to be an astronaut?

Minimum requirements to be an astronaut

To be considered for the NASA astronaut program is you must be a U.S. citizen. Dual citizenship is okay.

Beyond that, NASA sets three bare minimum requirements for their astronaut application. First, applicants must have a bachelor’s degree in engineering, biological or physical science, computer science, or math. Second, you must have three years of related professional experience or 1,000 hours of piloting. That professional experience could be teaching or time spent pursuing an advanced degree. And third, you must be able to pass something called the NASA long-duration Astronaut physical.

As part of that physical, you will have to be able to demonstrate 20/20 vision, although using glasses or having had LASIK surgery to do that is okay.

Age requirements

It may surprise you to learn that there are no age requirements for being an astronaut. (Of course, you have to be old enough to have met the professional requirements and able to pass the physical.) The typical age range spans 26 to 46-years-old.

Astronaut John Glenn, who made history as the first American to orbit earth, returned to space at age 77 as a payload specialist on the space shuttle Discovery. Over the nine-day mission, he participated in research to test the effects of microgravity on the aging body.

Physical requirements

There is also no specific body type required to be an astronaut, but you do have to fit in the spacesuit—called the extravehicular mobility unit—that the astronauts wear to do spacewalks. This may sound obvious, but spacesuits have historically been designed for men. In the 1970s, NASA offered an extra-small and small version of the men’s suit, but those still didn’t account for different the body types many women have, like larger hips and narrower shoulders. And budget cuts in the 1990s meant they did away with those smaller sizes altogether.

This may sound obvious, but spacesuits have historically been designed for men.

In March of 2019, NASA scheduled what was to be the first all-female spacewalk, but the historical event had to be canceled because there were not enough spacesuits to fit both women at the same time. Finally, in October later that year, the first all-female spacewalk did take place, with astronauts Jessica Meir and Christina Koch. A woman has not yet walked on the Moon.

Myths about astronaut requirements

As a teenager, I was told that getting a tattoo would mean I could never be an astronaut. This is not at all true. In fact, some Apollo astronauts were given tattoos– small dots to show where defibrillator pads should be placed in case of a medical emergency. Perhaps whoever told me the myth about astronauts not being able to have tattoos was trying to discourage me from getting one. (Sorry! It didn’t work.)

What kind of training is required to be an astronaut?

Being selected as an astronaut candidate is only the beginning. You will then have to pass extensive physically and intellectually demanding training.

If your goal is to become an astronaut or just want to know how to get in shape fast, check out this Get-Fit Guy podcast episode about the basics of strength training. Listen in this player: 

NASA astronauts are required to pass military water survival training, pass a flying syllabus, and become SCUBA qualified, which includes a swim test. They also have to successfully complete training on the systems that run the International Space Station, extravehicular activity skills training (that’s practice for spacewalks), robotics skills training, and aircraft flight readiness training.

Oh, and you’d have to learn Russian!

So, how do you train to operate complex equipment like that inside the International Space Station in a microgravity environment while still firmly planted here on Earth? NASA astronauts use the Neutral Buoyancy Laboratory (the NBL), which is, in very formal scientific terms, one of the coolest things I’ve ever seen.

The main part of the facility, which is near the Johnson Space Center in Houston, Texas, is essentially an enormous pool. Astronauts wear suits that create neutral buoyancy. Then, they practice manipulating full-scale replicas of the International Space Station modules as well as vehicles that visit the ISS like the Japanese HTV, the European ATV, and the SpaceX Dragon.

Neutral buoyancy means the average density of an object matches the density of the water (or other fluid) that surrounds it so that the buoyant force—that’s what holds you aloft in the water—exactly matches the force of gravity that would otherwise make you sink. This feeling of limbo—of neither sinking nor rising to the top of the pool—simulates the microgravity environment of space.

The astronauts are lowered into the pool with a crane and weighted properly to achieve neutral buoyancy. The simulated environment isn’t perfect though—there’s still a drag force as the trainees move through the water. That’s something they would not experience in space.

The pool is 202 feet (that’s 62 meters) long, 102 feet (about 31 meters) wide, and just over 40 feet (about 12 meters) deep. It holds 6.2 million gallons of water.

Astronaut requirements in other countries

The European Space Agency (ESA), highlights similar requirements for becoming an astronaut on their website. Although they allow the use of glasses, they note that most disqualifications occur because of vision issues, or an applicant’s inability to pass tests that check for visual acuity, color perception, and 3D vision.

The European Space Agency includes the importance of public relations skills when describing an astronaut’s job.

Interestingly, the ESA also highlights the importance of public relations when describing an astronaut’s job. They say that astronauts “must enjoy meeting the public and the press, and be able to communicate the importance of their tasks in space.”

The ESA has not had a recruitment campaign for new astronauts since 2009. During that call, ESA received 8,413 qualified applications and selected just six.

It was harder for me to find the precise requirements to become a cosmonaut, a Russian astronaut, but that’s likely because I don’t know the right places to look and not that the program is any sort of secret. One article on the process noted that prior to 2012, cosmonauts had only been selected from the Air Force or from among the engineering groups and other agencies closely linked to the space program. In the first open call in 2012, applicants were required to be a Russian citizen, have a higher education in certain specified fields, be in good health, and be under the age of 35.

What are the odds of becoming an astronaut?

Do you think you fit these requirements? Once you apply, either as a civilian or through the military, NASA does a preliminary screening to identify people who hit the minimum markers and then reaches out to them and their references. Finalists will make it to a further in-person stage, including a week of medical screenings, personal interviews, and orientation.

Each group of astronaut recruits has its own name. The most recent class has been dubbed The Turtles.

So what are your chances of becoming a U.S. astronaut? NASA held a recruitment campaign in 2015-2016 and received what they called a record-breaking number of applications with more than 18,300. In 2017, they announced their largest astronaut class so far—12 new recruits. Each group of astronaut recruits has its own name. They’ve been called things like The Mercury Seven, The Flying Escargot, or my favorite, The Scientists. The most recent class has been dubbed The Turtles.

We don’t know when NASA’s next open call for a new astronaut class will be, but given the recent selection of The Turtles, it isn’t likely to be for a while. But hey, that means we all have plenty of time to train!