Former NASA astronaut William Thornton speaks to guests at the Astronaut Scholarship Foundation's event celebrating the 40th anniversary of Skylab.

At the Kennedy Space Center's Apollo/Saturn V Center, former NASA astronaut William Thornton speaks to guests at the Astronaut Scholarship Foundation's event celebrating the 40th anniversary of Skylab. Thornton, along with astronauts Robert Crippen and Karol Bobko, took part in a 56-day activity during 1972 called SMEAT -- Skylab Medical Experiment Altitude Test -- that preceded the launch of Skylab and helped NASA evaluate equipment and procedures proposed for the long-duration Skylab missions. Thornton went on to fly missions during the Space Shuttle Program.

The gala commemorating the 40th anniversary of Skylab included six of the nine astronauts who flew missions to America's first space station. The orbiting laboratory was launched unpiloted from Kennedy on May 14, 1973. Between May 25, 1973 and Feb. 8, 1974, crews of three spent 28, 59 and 84 days living and working in low-Earth orbit aboard the station. For more information, visit http://www.nasa.gov/mission_pages/skylab/ Photo credit: NASA/Kim Shiflett