It was designed to protect shuttle crew in the event of loss of cabin pressure at altitudes up to 30 km, but unlike the LES it was a full-pressure suit. It also served to insulate the crew from cold air or water temperatures after a bail out from the shuttle. During re-entry, the same anti-G protection system used in LES, consisting of pressure bladders in the legs and lower abdomen, fought pooling of blood in the lower body after prolonged exposure to microgravity. The suit also protected the crew from any contamination in the cabin atmosphere. ACES also provided a liquid cooling undergarment.
The S1035 ACES incorporated further refinements and was a true full pressure type garment developed, again, using proven and qualified technology from the most recent USAF Advanced Lightweight Pressure Suit (David Clark model S1034). The suit included integrated life support subsystems with breathable bladders. The S1035 ACES began initial service use on NASA mission STS-64, 9 September 1994.