How Space Suits Work

Project Apollo Space Suit

Neil Armstrong's Apollo 11 space suit
Photo courtesy NASA

Because Apollo astronauts had to walk on the moon as well as fly in space, a single space suit was developed that had add-ons for moonwalking. The basic Apollo space suit, which was worn during liftoff, was the backup suit needed in case cabin pressure failed.

The Apollo suit consisted of the following:


  • A water-cooled nylon undergarment
  • A multi-layered pressure suit: inside layer - lightweight nylon with fabric vents; middle layer - neoprene-coated nylon to hold pressure; outer layer - nylon to restrain the pressurized layers beneath
  • Five layers of aluminized Mylar interwoven with four layers of Dacron for heat protection
  • Two layers of Kapton for additional heat protection
  • A layer of Teflon-coated cloth (nonflammable) for protection from scrapes
  • A layer of white Teflon cloth (nonflammable)

The suit had boots, gloves, a communications cap and a clear plastic helmet. During liftoff, the suit's oxygen and cooling water were supplied by the ship.

For walking on the moon, the space suit was supplemented with a pair of protective overboots, gloves with rubber fingertips, a set of filters/visors worn over the helmet for protection from sunlight, and a portable life support backpack that contained oxygen, carbon-dioxide removal equipment and cooling water. The space suit and backpack weighed 180 lb on Earth, but only 30 lb on the moon.

The basic Apollo space suit was also used for spacewalking during the Skylab missions.

During the early flights of the space shuttle, astronauts wore a brown flight suit. Like earlier missions, this flight suit was meant to protect the astronauts if the cabin pressure failed. Its design was similar to the earlier flight suits of Apollo.

As shuttle flights became more routine, the astronauts stopped wearing pressurized suits during liftoff. Instead, they wore light-blue coveralls with black boots and a white, plastic, impact-resistant, communications helmet. This practice was continued until the Challenger disaster.

Latest shuttle flightsuit used during liftoff and re-entry
Photo courtesy NASA

After a review of the Challenger disaster, NASA started requiring all astronauts to wear pressurized suits during liftoff and re-entry. These orange flight suits are pressurized and equipped with a communications cap, helmet, boots, gloves, parachute, and inflatable life preserver. Again, these space suits are designed only for emergency use -- in case the cabin pressure fails or the astronauts have to eject from the spacecraft at high altitude during liftoff or re-entry. We will discuss the current space suit (Extravehicular Mobility Unit or EMU) that is used for spacewalking from the shuttle and International Space Station in the next section.