To attach the astronaut to the spacecraft during extravehicular operations, a tether long enough to allow access to the spacecraft adapter section would be used; it would include 12 nylon-encapsulated communications wires. The tether's only purpose was to attach the astronaut to the spacecraft; maneuvering and maintaining stability would be accomplished by other means. Provisions for extravehicular operations were to be provided from spacecraft No. 4 on. One-half hour of useful time outside the cabin was specified as the basis for systems design.