of eight solar flares and produced valuable results that scientists stated would have been impossible to obtain with uncrewed spacecraft. The existence of the Sun's coronal holes was confirmed because of these efforts. Many of the experiments conducted investigated the astronauts' adaptation to extended periods of microgravity. A typical day began at 6 a.m. Central Time Zone. Although the toilet was small and noisy, both veteran astronauts who had endured earlier missions' rudimentary waste-collection systems and rookies complimented it. The first crew enjoyed taking a shower once a week, but found drying themselves in weightlessness and vacuuming excess water difficult; later crews usually cleaned themselves daily with wet washcloths instead of using the shower. Astronauts also found that bending over in weightlessness to put on socks or tie shoelaces strained their abdominal muscles. Breakfast began at 7 a.m. Astronauts usually stood to eat, as sitting in microgravity also strained their abdominal muscles. They reported that their food although greatly improved from Apollo was bland and repetitive, and weightlessness caused utensils, food containers, and bits of food to float away; also, gas in their drinking water contributed to flatulence. After breakfast and preparation for lunch, experiments, tests and repairs of spacecraft systems and, if possible, 90 minutes of physical exercise followed; the station had a bicycle and other equipment, and astronauts could jog around the water tank. After dinner, which was scheduled for 6 p.m., crews performed household chores and prepared for the next day's experiments. Following lengthy daily instructions (some of which were up to 15 meters long) sent via teleprinter, the crews were often busy enough to postpone sleep. The station offered what a later study called "a highly satisfactory living and working environment for crews", with enough room for personal privacy. Although it had a dart set, playing cards, and other recreational equipment in addition to books and music players, the window with its view of Earth became the most popular way to relax in orbit. Experiments Prior to departure about 80 experiments were named, although they are also described as "almost 300 separate investigations". Experiments were divided into six broad categories: Life science – human physiology, biomedical research; circadian rhythms (mice, gnats) Solar physics and astronomy – sun observations (eight telescopes and separate instrumentation); Comet Kohoutek (Skylab 4); stellar observations; space physics Earth resources – mineral resources; geology; hurricanes; land and vegetation patterns Material science – welding,