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What Is a Spacesuit?
David Hitt

A spacesuit is much more than a set of clothes astronauts wear on spacewalks. A fully equipped spacesuit is really a one-person spacecraft. The formal name for the spacesuit used on the space shuttle and International Space Station is 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 spacesuit protects the astronaut from the dangers of being outside in space.

Why Do Astronauts Need Spacesuits?

Spacesuits help astronauts in several ways. Spacewalking astronauts face a wide variety of temperatures. In Earth's orbit, conditions can be as cold as minus 250 degrees Fahrenheit. In the sunlight, they can be as hot as 250 degrees. A spacesuit protects astronauts from those extreme temperatures.

Spacesuits also supply astronauts with oxygen to breathe while they are in the vacuum of space. They contain water to drink during spacewalks. They protect astronauts from being injured from impacts of small bits of space dust. Space dust may not sound very dangerous, but when even a tiny object is moving many times faster than a bullet, it can cause injury. Spacesuits also protect astronauts from radiation in space. The suits even have visors to protect astronauts' eyes from the bright sunlight.

What Are the Parts of a Spacesuit?

The spacesuit consists of several pieces. The Hard Upper Torso covers the astronaut's chest. The arm assembly covers the arms and connects to the gloves. The helmet and Extravehicular Visor Assembly are designed to protect the astronaut's head while still allowing him or her to see as much as possible. The Lower Torso Assembly covers the astronaut's legs and feet. The flexible parts of the suit are made from several layers of material. The layers perform different functions, from keeping oxygen within the spacesuit to protecting from space dust impacts.

Underneath the spacesuit, astronauts wear a Liquid Cooling and Ventilation Garment. Tubes are woven into this tight-fitting piece of clothing that covers the entire body except for the head, hands and feet. Water flows through these tubes to keep the astronaut cool during the spacewalk.

On the back of the spacesuit is a backpack called the Primary Life Support Subsystem. This backpack contains the oxygen that astronauts breathe during a spacewalk. It also removes carbon dioxide that astronauts exhale. The backpack also provides electricity for the suit. A fan moves the oxygen through the spacesuit and life support systems, and a water tank holds the cooling water that flows through the Liquid Cooling and Ventilation Garment.

Also attached to the back of the suit is a device called the Simplified Aid for Extravehicular Activity Rescue, or SAFER. SAFER has several small thruster jets. If an astronaut became separated from the space station, he or she could use SAFER to fly back.

What Other Spacesuits Have Astronauts Worn?

NASA's first spacesuits were developed for the Mercury program. Mercury was the first time NASA astronauts flew into space. These simple suits were based on pressure suits worn by U. S. Navy pilots. Astronauts did not go on spacewalks then. The Mercury suits were worn only inside the spacecraft.

NASA's first spacewalks took place during the Gemini program. The suits used for Gemini were more advanced than the Mercury suits. But the Gemini suits were simpler than today's spacesuits. These suits did not contain their own life support. Instead, they connected to life support systems on the Gemini spacecraft with a cord called the umbilical.

Spacesuits designed for the Apollo program had to do things the first suits did not. These spacesuits had to protect astronauts walking on the moon. Unlike the other suits, the Apollo suits had boots made to walk on a rocky surface. The Apollo suits also contained a life support system, similar to the Portable Life Support Subsystem on the current suit. Having a life support system on the spacesuit allowed the astronauts to explore away from the lunar lander. Spacesuits similar to the Apollo suits were used on the Skylab space station. Like the Gemini suits, the Skylab suits connected to life support systems on the spacecraft via an umbilical.

What Spacesuits Are Worn Today?

In addition to the EMU, NASA astronauts wear other suits today. The Advanced Crew Escape Suit is the orange suit that astronauts wear during launch and landing of the space shuttle. This suit cannot be worn during spacewalks. Sometimes, NASA astronauts will wear the Russian Orlan spacesuit. This suit is the Russian version of the EMU and is used for spacewalks. Another Russian suit is the Sokol. Like the Advanced Crew Escape Suit, the Sokol is designed only to be used inside a spacecraft. It is used on the Russian Soyuz spacecraft.