S73-20759 (1 March 1973) --- Astronaut Charles Conrad Jr., commander of the first manned Skylab mission, takes items from the M512 materials processing equipment storage assembly during Skylab training at Johnson Space Center. Conrad is standing in the Multiple Docking Adapter (MDA) trainer in the JSC Mission Simulation and Training Facility. The assembly holds equipment designed to explore space manufacturing capability in a weightless state. Conrad is holding one of the experiment parts in his left hand. Photo credit: NASA