NASA - National Aeronautics and Space Administration

When astronauts venture into space, they wear spacesuits for protection from the dangers of space. The large, white protective suits they wear during spacewalks outside their vehicles are like miniature spacecraft.

In space …	So, spacesuits have …
There is no air to breathe.	Oxygen tanks.
There is no air pressure to keep body fluids such as blood from boiling and gases in the body from expanding.	A pressure layer to keep body fluids and gases in their proper state.
Temperatures can be extremely high, up to 250 degrees Fahrenheit.	A layer with tubes through which water flows and cools the body.
Temperatures can also be extremely cold, as low as minus 250 degrees Fahrenheit.	Layers to insulate the body from cool temperatures.
Tiny, high-speed space rocks called micrometeoroids can injure astronauts.	Several layers of protective materials to prevent damage from micrometeoroids.

Just as a spacecraft has many functions, a spacesuit does more than just provide protection and oxygen. A battery supplies electrical power. A two-way radio lets spacewalkers communicate with the rest of the crew. Gauges and controls allow astronauts to be sure their suits are working correctly.

Spacesuits have changed a lot in NASA's 50-year history. The first suits were metallic-silver pressure suits, similar to the ones that Navy pilots wore when flying at high altitudes. Spacesuits have been changed over the years to be more comfortable for astronauts and to meet new challenges as the missions in space changed. The current U.S. spacesuit worn during spacewalks is called the extravehicular mobility unit, or EMU. "Extravehicular" means outside of the vehicle or spacecraft. "Mobility" means that the astronaut can move around in the suit.

The EMU works well for spacewalks outside the space shuttle and the International Space Station. But as NASA goes back to the moon and on to Mars, spacewalks will be different. Astronauts will use spacesuits more often. They will need to last longer. They will also need to be more flexible. Explorers will have to be able to move as freely as possible as they explore craters on the moon and climb the valleys and volcanoes of the Red Planet.

More About Spacesuits
Spacesuits and Spacewalks Web site
Gallery: Evolution of the NASA Spacesuit


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