SLM-1 or Skylab 2  had the first of three crews to inhabit the orbiting space station.

Since the Skylab was first launched as an unmanned Orbital Workshop, NASA officially listed this first manned mission as Skylab 1.

This was the first three-man crew to stay in space for 28 days; the first repairs were made on an orbiting space station; the first occupancy of a U. S. space station and operation of its scientific instruments and life-support systems (including obtaining extensive physiological measurement data).

On the 28th day, the crew re-entered the Command Module, undocked and returned to Earth, landing safely in the Pacific Ocean southwest of California.

Launch Date: May 25, 1973 at 9:00 AM EDT

Launch Vehicle: Saturn 1B

Crew: Commander: Charles "Pete" Conrad, Science Pilot: Dr. Joseph P. Kerwin (First medical doctor in space.), Pilot: Paul J. Weitz

Approximately 4” Diameter