Why Do Astronauts Train Underwater?

Space’s environment is very different from the earth’s. One thing that creates a major difference is gravity. Due to the absence of gravity in space, completing a mission is not an easy to crack for astronauts. Therefore, going to space without enough preparation would be a high-risk job.

This is why NASA effectively train its astronauts before sending them on a space mission. But a question that many space lovers ask is, “why do astronauts train underwater?”. Let’s find the answer!

Why Do Astronauts Train Underwater?

It is sort of a rehearsal or training for astronauts to get familiar with the similar conditions they will experience in space. The most challenging factor during a space mission is nothing but weightlessness. This is where underwater training lends a helping hand to the astronauts.

Before performing extra-vehicular activities in space, astronauts practice them in neutral buoyancy underwater. Doing this gives them a solid idea of understanding the space’s atmosphere. The underwater training helps them learn how to reposition themselves and provide force without utilizing their body weights.

Does NASA Train Its Astronauts Underwater?

Yes, NASA encourages its astronauts to get as much underwater training as possible to better understand space’s conditions. In fact, NASA has its own aquatic astronaut training facility – Neutral Buoyancy Lab (NBL). This lab is located in Houston, Texas.

Crew Training Underwater In The NBL. Credit: NASA/Mark Sowa

Nick Hague – a well-known American astronaut – said that whenever he wants to do a task experiencing weightlessness, he goes to NBL. This facility consists of an indoor pool. The astronauts planning to go for a space mission utilize this pool to do simulated EVA activities.

Since How Long Has NASA Been Training Its Astronauts Underwater?

Now, you have got the answer to the question, “why do astronauts train underwater?”. It is time to explore how long NASA has been training its astronauts underwater.

The astronauts working at NASA have been receiving intensive underwater training since 2001. It was the year when the NASA Extreme Environment Operation (NEEMO) program was started for the very first time. This unique program is designed to train astronauts for upcoming space missions.

NEEMO is a one-of-its-kind undersea space research station in the US where scientists, engineers, and astronauts test equipment and get underwater training for approximately three consecutive weeks.

Can Astronauts Swim in Water in Space?

Yes, they can swim in a sense. However, the overall swimming process will be pretty slow. This is because the viscosity of air or space is very low compared to water. Therefore, the scoop of the fluid must be higher to move you around by propelling it with your feet and hands.

On the other hand, swimming on earth is super easy. When you push water with your hands and feet, it pushes you back, and you can move around conveniently. As soon as you go into space, this force gets removed due to zero gravity. As a result, the movement of astronauts in water in space becomes super slow.

Can Astronauts Go Underwater Wearing Space Suits?

Yes, they can go for an underwater training program wearing space suits. The aim was to get trained for spacewalks in a low-gravity environment. The NBL comprises a 40-feet deep pool of water that provides astronauts with the ideal conditions to test their abilities and polish practical skills.

The space suits not only provide a vacuum of space but also ensure a continuous supply of oxygen for astronauts to breathe. These suits are practical underwater at a specific depth. So, getting deep enough in the water and wearing space suits is not a good approach.

How Long Does It Take for an Astronaut to Complete Underwater Training?

The training of astronauts and performance evaluation underwater lasts for up to two years. Before considering an astronaut for any space mission, nine rehearsals are required underwater. This training develops all the skills needed for a formal space mission.

Many astronauts do a lot more than nine rehearsals to get hands-on experience to make their future space mission(s) less challenging. The astronauts who plan to go on another mission after years of gap, rehearse many times to regain their confidence.

Is The Astronaut Training Costly?

The National Aerospace Training and Research (NATAR) is a top-grade company that has been providing complete astronaut training for many years. It utilizes an advanced centrifuge with state-of-the-art equipment. The cost of only a centrifuge can go up to millions of dollars.

According to Glenn King (director of space training at NASTAR), the complete astronaut training at NASTAR can cost you approximately $15,000. This is not a huge amount for those planning to go on a space mission in the near future. Before you choose a specific training institute, don’t forget to ensure that it has reliable equipment and highly qualified space trainers.

One of the online resources states that NASA spends approximately $15 million to train an astronaut for a space mission.

How Much Time Do Astronauts Spend Underwater?

Though astronauts have college and university degrees, professional practice is still necessary to get solid practical exposure. While practicing underwater, they mostly spend around seven hours at a time.

The more time they spend in the water, the more experience (similar to space) they will gain because practice makes a man perfect. As a result, the actual space flight will become less challenging for them.

What Sets NASA Training Apart?

A long time ago, NASA decided to train its astronauts under the surface (maintaining neutral buoyancy conditions) to make them well familiar with the zero-G space environment. The agency went the extra mile in 1995 by building the largest underwater astronaut training lab – Neutral Buoyancy Lab.

The advanced space suits and the tools equipped with the latest technology help astronauts get extremely professional space training to make their missions successful to a great extent.


Why do astronauts train underwater? It is the most common question being asked by space enthusiasts. These professionals get training underwater because they can experience the effect of weightlessness very well deep in the water (in neutral buoyancy conditions).

This is what astronauts have to experience in space, where they exert force without using their body weights. NASA and NASTAR also encourage astronauts to get underwater training before they go on a space mission.

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Astronomy has mesmerized me since my father introduced me to space magazines and telescopes. My dedication to astronomy and the pursuit of knowledge has led me to various places, experts, and answers I hope to share with everyone one day.

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