CAPE CANAVERAL, Fla. -- Thirty years ago the United States acquired its initial experience operating a scientific workshop in orbit over Earth. Three crews of three astronauts spent much of 1973 and 1974 aboard a laboratory called Skylab, seen here in this view of the station taken during the second manned mission.

Assembled from hardware built for Project Apollo, Skylab was an empty third stage of the Saturn 5 Moon rocket in which the liquid hydrogen tank was configured with all the comforts of home, while the empty liquid oxygen tank served as a giant trash container. A docking module added to the top of the stage also held in place a solar telescope and attached windmill-shaped solar array.

The workshop was launched into low Earth orbit atop a two-stage version of the Saturn 5 on May 14, 1973. The station's thermal protection shield was ripped free during the climb through the atmosphere and nearly crippled the program. Fast action by NASA saved the station when the first crew was launched 11 days later with a repair kit.

Each of the crews were launched to the station in Apollo command and service modules atop Saturn 1B rockets. The crews spent 28, 59 and 84 days in space, respectively, giving the U.S. it's first exposure to long-duration spaceflight. Standard tours of duty aboard today's International Space Station is about six months.

Skylab became infamous for its uncontrolled plunge through Earth's atmosphere in 1979, raining debris over the Indian Ocean and western Australia.

CREDIT: NASA