AX-5

American space suit, tested 1985. The AX-5 high pressure, zero prebreathe hard suit was developed at NASA Ames Research Center in the 1980s. It achieved mobility through a constant volume, using a hard metal/composite rigid exoskeleton design.

Although this minimized the torque required to bend the joints, it made the suits heavy and potentially uncomfortable to wear. Typically hard suits required additional internal padding for astronauts in order to reduce the risk of injury due to contact with the hard interior of the suit. While NASA struggled to develop such space suits, the commercial deep sea diving community developed hard, pod-like suits at an order-of-magnitude less cost and used them routinely and successfully.