When humans go into space, they face conditions far different from those on the earth. There is no air, and the gravitational forces experienced by the astronauts will be quite different than those they experience on Earth. All food and water must be carried along. Temperatures vary greatly. Astronauts have to rely on sophisticated equipment to enable them to survive this hostile environment.

From the first Mercury flight on February 20, 1962 to recent space shuttle missions, scientists have endeavored to design space equipment that makes orbital flight possible for human beings. During the Mercury missions, astronauts depended on a dual life support system, one subsystem to maintain temperature and pressure for the spacecraft cabin and the other for within the pilot's suit.

The early spacesuit was bulky, its many layers prohibiting easy movement by the astronauts. Air was propelled through the suit, exiting the helmet and passing...