[1] Skylab, a versatile scientific and engineering laboratory (fig. 1-1), was launched into Earth orbit on May 14, 1973, on a Saturn V rocket. Three crews of three men each subsequently visited the space station during extended missions for a total of 171 days of manned occupancy. A Saturn IB rocket launched each three-man crew in an Apollo spacecraft that was also the reentry vehicle. The manned missions lasted 28, 59, and 84 days (fig. 1-2). During the flight out of the Earth's atmosphere, Skylab's micrometeoroid and heat shield was unexpectedly torn off. A specially built parasol to shield the space station was therefore sent up with the first crew, whose launch was consequently delayed until May 25, 1973. The second crew was launched on July 28, and the third on November 16. The last mission was originally planned for 56 days, but because the...