One considered option was to use Saturn V SA-515 to launch the backup Skylab station into orbit sometime between January 1975 and April 1976.

Some uses considered for the second Skylab module included putting it into a rotation mode where it could generate artificial gravity and a plan to celebrate the 1976 United States Bicentennial with the launch of two Soviet Soyuz missions to the back-up Skylab.

For future missions, the station, which would have then been called the Advanced Skylab, could have been expanded by the Space Shuttle, which was due to enter service in 1979.

[3] Saturn V SA-515 was originally designated for Apollo 20, and later to launch the backup Skylab station into orbit sometime between January 1975 and April 1976.

Multiple Docking Adapter is on display at the Kennedy Space Center Visitor Complex.

This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.