Project Mercury

Project Mercury astronauts. (Front row, left to right) Walter M. Schirra, Jr., Donald K. Slayton, John H. Glenn, Jr., M.Scott Carpenter. (Back row, left to right) Alan B. Shepard, Jr., Virgil I. Grissom, L. Gordon Cooper, Jr.

By the time NASA began the Mercury manned space flight program, the best full-pressure suit design consisted of an inner gas-bladder layer of neoprene-coated fabric and an outer restraint layer of aluminized nylon. The first layer retained pure oxygen at 34.5 kilopascals; the second layer prevented the first from expanding like a balloon. This second fabric restraint layer directed the oxygen pressure inward on the astronaut. The limbs of the suit did not bend in a hinge fashion as do human arms and legs. Instead, the fabric arms and legs bent in a gentle curve, which restricted movement. When the astronaut moved one of his arms, the bending creased or folded the fabric inward near the joints, decreasing the volume of the suit and increasing its total pressure slightly. Fortunately for the comfort of the Mercury astronauts, the Mercury suit was designed to serve only as a pressure backup if the spacecraft cabin decompressed. No Mercury capsule ever lost pressure during a mission, and the suits remained uninflated.

Editor:Yang Jie