10 Surprising Facts About Astronaut Training

While NASA doesn't have any limits on how old its astronauts need to be to visit space, it does require potential candidates to have a bachelor's degree in a STEM-related field such as biology, engineering or computer science. NASA also requires that all astronaut trainees be U.S. citizens with excellent vision, though the use of glasses is acceptable. And finally, successful candidates must have either 1,000 hours' worth of piloting experience in a jet aircraft or three years of relevant work experience [source: NASA].

But no, there are no official age restrictions. In the past, NASA has selected candidates who were as young as 26 and as old as 46 [source: NASA]. And the late astronaut John Glenn returned to space in 1998 at the age of 77.

Now, the odds of actually getting chosen, however, are ... well, they're astronomical. In 2016, NASA announced that a handful of new people would be allowed to enter its astronaut training program. The administration was then flooded with more than 18,300 applications. Only 12 of these hopefuls were chosen [source: Ward]. That's an acceptance rate of just 0.065 percent!

Normally, the selection process consists of two rounds. NASA begins by interviewing about 120 of the most promising candidates. From that pool, the top eight to 14 applicants enter the newest official class of astronaut candidates [source: Ziv].

Basic training for NASA astronaut candidates takes up to two years. Those who graduate become full astronauts, but that doesn't mean they head right into space (keep reading). So far, there have been 22 classes of NASA astronauts, many of which received cutesy nicknames. For example, the classes of 1996 and 1998 were called the "sardines" and "penguins," respectively [source: Wattles].

All of the required swimming came as a bit of a shock to astronaut Mike Massimino, who's said that he barely knew how to swim when NASA selected him for astronaut candidate training [source: Massimino].

During a candidate's first month of training, he or she must pass a truly rigorous swim test. Would-be astronauts begin by swimming three full lengths of a 25-meter (82-foot) pool without stopping. Oh, and did we mention that the swimmers need to do this while wearing tennis shoes and a flight suit weighing around 250 pounds (127 kilograms) [source: Ward]?

When completing this portion of the test, astronaut candidates may use one of three strokes: the freestyle stroke, the breaststroke or the sidestroke. They're allowed to take as much time as they need but immediately after they've completed all three lengths of the pool, the candidates then must tread water for 10 minutes. NASA also requires its astronauts to become scuba certified [source: Clement]. We'll explain why later.

Astronaut candidates with no prior piloting experience are also put through a Navy-run water survival training course. Among other things, the trainees are taught how to deploy rafts and engage with rescue vehicles. For many years, astronauts went through the entire ordeal in the Gulf of Mexico, but the course was recently been moved into an indoor pool at a military station in Pensacola, Florida [source: U.S. Air Force].

As for Massimino, he passed his swimming and water survival tests with flying colors. And poetically enough, the astronaut took one of Michael Phelps' swim caps into orbit on his last space flight [source: Discovery].

You don't need a telescope to know that the moon is littered with craters. A few of the biggest are sometimes visible to the naked, Earth-bound eye [source: King].

Altogether, our planet's natural satellite has thousands of these depressions. So, after the Apollo program was founded in 1961, NASA decided to get its astronauts used to crater-laden terrain. But how? While meteorite impact craters are a dime a dozen on the moon, they're few and far between here on Earth [source: NASA].

Fortunately, the agency had a good-sized crater right in its own backyard. Around 50,000 years ago, a meteorite smacked into what's now northern Arizona. The result was one gigantic hole in the ground with a depth of 570 feet (173.7 meters) and a width of 4,100 feet (1.25 kilometers). Simply known as "Meteor Crater," the indentation's been of great use to NASA. During the Apollo era, future astronauts conducted mapping and surveying drills in and around the crater. It's still a field trip destination for NASA trainees today [source: Davis].

For would-be moonwalkers, isolated craters are great places to carry out some exercises. But a whole field of them would be even better. To that end, in 1963, NASA and the U.S. Geological Survey mapped out a section of the moon's surface. Then they used dynamite — lots and lots of dynamite — to make a few hundred replica craters in a dry expanse near Flagstaff, Arizona. When the site (known as "Cinder Lake") was all prepared, Apollo astronauts got to test-drive rovers across the terrain. Soil sampling drills were also carried out there [source: Northern Arizona University].

Right now, the only way to get up to the International Space Station (ISS) is by hitching a ride on a Russian ship. The Soyuz line of spacecrafts was originally created for the Soviet lunar program in the early 1960s. Since then, Soyuz ships have carried out over 1,500 launches. The vehicles include a capsule where the astronauts sit atop a set of detachable rocket boosters. Modern Soyuz crafts blast off from a cosmodrome (i.e.: "space port") located in Kazakhstan [source: NASA].

The ISS uses Soyuz ships to ferry over supplies and transport its astronauts to and from Earth. No other vehicles are currently being employed to make such manned missions. In other words, anyone who wants to visit the ISS had better brush up on their Russian [source: McKie].

All ISS astronauts, regardless of national origin, are now required to study the language. And we're not just talking about basic greetings here. Astronauts need to understand a lot of technical jargon in the Russian tongue. For some of them, it's a daunting challenge. European Space Agency astronaut and ISS crew member Tim Peake has gone on the record as saying that learning Russian was the toughest aspect of his training [source: Knapton].

Today NASA puts its future space travelers through intensive language tutoring. In every American astronaut's schedule, a large amount of time is set aside for one-on-one meetings with Russian teachers. And like foreign exchange students, some of the NASA trainees are sent to live with host families in Moscow for a few weeks [source: Howell].

Near the Johnson Space Center in Houston, Texas, is a gigantic indoor pool. This thing measures 40 feet (12.1 meters) deep, 202 feet (61.5 meters) long and 102 feet (31 meters) wide. At that size, it's bigger than an Olympic swimming pool. The water is kept at a balmy temperature between 82 to 86 degrees Fahrenheit (27 to 30 degrees Celsius) and recycled daily [source: NASA].

Here, astronauts can get themselves accustomed to the sense of weightlessness they'll experience in outer space. The pool is officially known as the Neutral Buoyancy Laboratory — or NBL for short. On training days, astronauts (who get scuba certified early on) are zipped into their space suits and lowered into the water. Under the surface, each trainee is escorted by two safety divers and taken to various corners of the pool [source: Terdiman].

NASA has full-sized replicas of a Soyuz spacecraft, a portion of the ISS, and other pieces of equipment. These can be dropped into the pool for hands-on training purposes. Submerged astronauts go through docking drills, ship-repairing exercises and other activities that simulate the jobs they'll need to do during space walks. Suffice it to say that aspiring space travelers get to know the pool quite well. It's now common practice for an astronaut to spend six to eight hours in the NBL for every one hour he or she will get to spend on a spacewalk [source: Terdiman].

And in case you were wondering, the NBL isn't the only training pool of its kind. Similar facilities are maintained by the Chinese, Japanese, Russian and European space programs. There's also a neutral buoyancy pool at the University of Maryland [source: University of Maryland].

There's more than one way to make a person feel weightless. You can lower future astronauts into one of the Neutral Buoyancy Pools we just mentioned, or you give them a ride on a reduced-gravity air flight.

In 1959, NASA began working with the U.S. Air Force to modify ex-military planes so they could be used to train America's original class of astronauts (and test out space equipment). Thus began the saga of the lovingly nicknamed "Vomit Comets" [source: NASA].

With the right aircraft, it is possible to carry out flights that (briefly) subjected their riders to low-gravity conditions. To do this, a wide plane with padded walls and a roomy interior was required. For decades, NASA used KC-135 aircraft for this purpose. Passengers and trainees were loaded into the plane and then the pilots flew it in a wave-like ("parabolic") motion. That sent the plane through a series of upward climbs and rapid descents. When the trajectory was just right, people inside the aircraft would experience near-weightlessness for about 20 to 25 seconds on the downward falls [source: NASA].

As you can imagine, the experience made a lot of people nauseous. Estimates vary, but according to one article NASA ran in 2004, "about one in three first-time fliers" barfed on these rides. That's why astronauts traditionally called the planes "Vomit Comets."

Though NASA told us that its astronauts-in-training are no longer required to take microgravity flights, the astronaut candidate class of 2017 did get to experience one of these trips aboard a different specialized plane. The trip was made possible by a collaboration between NASA, the Canadian Space Agency (CSA) and Canada's National Research Council.

One of the most popular questions former International Space Station crew member Tim Peake gets asked is, "How do you go to the bathroom in space?" The short answer is "carefully." And it's a good idea to practice your form [source: Peake].

Because there's no gravity, extraterrestrial plumbing relies on vacuum suction. Nobody wants free-floating human waste, so the two toilets onboard the ISS are designed to actively suck down urine and feces. (Think high-tech vacuum cleaner.)

These commodes have long hoses affixed next to the seats where astronauts go No. 1. (Two interchangeable funnels are available for the crew members to use — one for males, the other for females.) After selecting the appropriate funnel, they attach it to the hose and then flip a switch to activate an internal fan that pulls their urine into a storage container [source: Izadi].

So what's the deal with pooping on these potties? It comes down to the same basic idea. Space travelers have to go into a tiny vacuum opening that's just 4 inches (10.16 centimeters) across. Most of us in the developed world have gotten used to toilet bowls that are at least three times wider. Aiming poo into such a narrow hole takes serious skill [source: Rowan].

For a time, two replicas of these old ISS toilets were on-site at the Johnson Space Center. The first was called the positional trainer. It wasn't functional, but it did have the exact dimensions of the genuine ISS potty. Inside the bowl, there was a camera that hooked up to a TV monitor facing the seat. Astronauts used that to check their aim while ... ahem, "aligning" themselves. Once a trainee got the hang of it, he or she would graduate onto the newer ISS replica toilet, which actually flushes [source: Rowan].

While these particular space johns are no longer in service — the newer toilets are part of wastewater system that recycles astronaut urine back into drinkable water — they still rely on suctions and vacuum, so astronauts still have to practice up on going potty.

In space, there's no shortage of hazardous situations. From micrometeorites to equipment snafus, astronauts must be ready to deal with all kinds of threats in low-Earth orbit. And then there are the return trips. Space agencies take great pains to ensure that their crews make it back home safely. Still, there's always a chance that something could go wrong.

What happens if a returning vessel is blown off-course and lands in dangerous territory? It's for this very reason that space agencies around the world put their astronauts through wilderness survival training. Back in the Apollo era, NASA's lunar program candidates were regularly tested out in the jungles of Panama. The men would attend survivalist lectures and then test their new skills at some remote location. (Buzz Aldrin remembers getting advice on how to hunt iguanas) [source: Wagener].

More recent classes of NASA astronauts have spent this phase of the training process in rural Maine. Guided by survival specialists from the U.S. armed forces, today's astronaut candidates go through plane crash drills, practice first aid and get acquainted with the emergency supply kits they'll have in space [source: Metcalf-Lindenberger].

Other astronaut hopefuls from various space programs around the world have been made to rough it in places like Nevada's sweltering deserts or Russia's frigid forests. Plus, the European Space Agency will sometimes leave its trainees adrift in the Mediterranean Sea [source: McKinnon].

At first, moving heavy equipment in outer space might seem like an easy chore. When gravity is low, it becomes possible for astronauts to shove huge objects around with their fingertips. But once a body's in motion, it tends to stay in motion — unless an outside force acts upon it. Let's say that one of the large, metallic chairs on your space station has come unhinged and now it's careening through the vessel. You'll need a skilled hand to slow down and redirect the thing.

That's where air-bearing floors come in handy. As it happens, astronaut trainees have them to practice on at the good old Johnson Space Center. Floors like this are metallic, room-sized, super-smooth and extremely well-polished. They also need to be level. On that score, the one at NASA definitely fits the bill: It's kept level to within 0.003 inches (0.007 centimeters) per foot (0.3 meters) [source: NASA].

So, what does one do with an air-bearing floor? Well, NASA affixes test pads to the bottoms of assorted objects. These create an air cushion between those objects and the floor itself. To paraphrase NASA's official website, that effectively transforms the floor into a room-sized air hockey table [source: NASA].

Astronaut candidates use the surface to prepare themselves for hauling large items through space. It also gives them the opportunity to test out their Manned Maneuvering Units (MMUs), which are personal transportation accessories that function a bit like jet packs [source: Shayler].

But why should NASA's people have all the fun? The European Space Agency's Orbital Robotics Lab has its own air-bearing floor as well [source: Industrial Equipment News].

With a combination of luck, skill and elbow grease, trainees that pass the rigorous program are selected as NASA astronaut candidates and then go on to graduate from the basic training process.

OK, so what happens then? Well, most won't actually be eligible to go up into space until the administration assigns them to their first mission. Then, they have to complete even more specialized training to prepare themselves for the journey. A rookie space traveler will generally embark upon his or her maiden voyage with a couple of veteran astronauts who double as his or her advisers [source: NASA].

Recent graduates of the basic training process may not receive their first mission assignment for a couple of years. During this so-called pre-assignment phase, most astronauts perform Earth-bound jobs like collaborating with their space program's engineers or serving as foreign liaisons. Dottie Metcalf-Lindenburger finished her general NASA training in 2006 but didn't venture into Earth's orbit until 2010. For those now going through a pre-assignment period, she recommends finding time to refresh your astronaut skill set [source: Metcalf-Lindenburger].

Over at the ESA, Swedish astronaut Christer Fuglesang spent 14 years in limbo before he was finally put on his first mission. On the other hand, Luca Parmitano of Italy managed to secure an assignment from the agency before he'd even finished basic training [source: Peake].