Skylab. NASA Skylab space station

This photograph shows the flight article of the Airlock Module (AM)/Multiple Docking Adapter (MDA) assembly being readied for testing in a clean room at the McDornell Douglas Plant in St. Louis, Missouri. Although the AM and the MDA were separate entities, they were in many respects simply two components of a single module. The AM enabled crew members to conduct extravehicular activities outside Skylab as required for experiment support. Oxygen and nitrogen storage tanks needed for Skylab's life support system were mounted on the external truss work of the AM. Major components in the AM included Skylab's electric power control and distribution station, environmental control system, communication system, and data handling and recording systems. The MDA, forward of the AM, provided docking facilities for the Command and Service Module. It also accommodated several experiment systems, among them the Earth Resource Experiment Package, the materials processing facility, and the control and display console needed for the Apollo Telescope Mount solar astronomy studies. The AM was built by McDonnell Douglas and the MDA was built by Martin Marietta. The Marshall Space Flight Center was responsible for the design and development of the Skylab hardware and experiment management.