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Spacewalk Training

As much fun as it is just to go to space, being able to go outside your spacecraft is even more exciting. But before you can float out the door into space, you must spend many hours learning how to do a spacewalk, or extravehicular activity (EVA).

In the NBL
IMAGE: An astronaut trains underwater.
An astronaut trains in the Neutral Buoyancy Laboratory, or NBL, at the Johnson Space Center, Houston, Texas.
Related Links
*A Day in the Life of a Spacewalker
*Space Station Extravehicular Activity
*Behind the Scenes: Sonny Carter Training Facility
*Meet Gavin Giere, training officer

First, you must learn how to put on your 127-kilogram (280-pound) spacesuit -- it will provide you with the air you need to breathe while you're outside your spacecraft. It will also keep your body at a comfortable temperature even though it may be 200 degrees below zero to 200 degrees above zero outside.

Because the suit is so large, you must practice moving around while wearing it and learn how to use tools with bulky gloves on your hands. Both astronauts and cosmonauts practice doing spacewalks in large pools -- astronauts usually spend seven hours training underwater for every hour they will spend spacewalking during a mission.

The Russians have a pool at the Gagarin Cosmonaut Training Center in Star City, Russia, where cosmonauts and astronauts learn how to use Russian spacesuits. Cosmonauts and astronauts train to use U.S. spacesuits in the Neutral Buoyancy Laboratory at the Johnson Space Center in Houston, Texas.

The NBL, as it's called, is a huge pool filled with 22.7 million liters (6.2 million gallons) of water. In fact, it's the world's largest indoor pool -- 62 meters (202 feet) long, 31 meters (102 feet) wide and 12 meters (40 feet) deep. At the bottom of the NBL sits a model of the International Space Station, which is the same size as the one orbiting the Earth -- that's why the NBL needs to be so big. There is also a model of the space shuttle's payload bay.

Being underwater in a pool is similar to being in space, but not quite the same. You're not truly weightless like in space, but are what is called neutrally buoyant. The term neutrally buoyant means an object doesn't want to float to the surface or sink to the bottom. Scuba divers try to be neutrally buoyant so they don't sink or float upwards when they're underwater. In the NBL, weights or floats will be attached to your spacesuit to make you neutrally buoyant. This makes you feel much like you will in space, when you're floating free without gravity.

IMAGE: Expedition 1 Commander Bill Shepherd
A crane lowers Expedition 1 Commander Bill Shepherd into the Hydrolab at the Gagarin Astronaut Training Center in Star City, Russia.

You will begin your training by going through your planned spacewalks while wearing standard scuba gear. Once you've gotten comfortable with all your assigned tasks, you will be start practicing them while wearing your spacesuit. In the pool, scuba divers will help you move around until you get used to moving in your spacesuit. They're also there to protect you in case you have a problem with your suit. You'll also learn how to stay in one place -- don't push too hard in space or you'll float away!

Next, you'll learn how to use all the tools you'll need during your spacewalk. If you're going to help build the International Space Station or work on the Hubble Space Telescope, you will practice only the specific tasks you will do in space. You will practice every task dozens of times before you ever leave the Earth, until you can do it correctly every time. If you're going to be part of a space station Expedition crew, you will learn how to do many tasks outside the space station, so you'll be ready to fix anything that might break.

By the time you're ready to fly into space, you will have spent more than 100 hours underwater practicing for your spacewalks. When the time comes to put on your suit and float out the door into the vacuum of space for the very first time, you'll know you're ready.

And while you're outside, don't forget to take some time to enjoy the view. You will remember that first view of the Earth through your helmet faceplate for the rest of your life.

Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 08/07/2003
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