"aerospace medicine, specialized branch of medical science concerned with those medical problems encountered in human flight in the atmosphere (aviation medicine) and beyond the atmosphere (space medicine). The ultimate aim of this specialty is to promote the safety and effectiveness of humans while they are exposed to the stresses of aerospace flight, such as extreme temperatures, low atmospheric pressure, radiation, noise, vibrations, oxygen deprivation, and the strong forces of acceleration and deceleration. Other hazards of space flight include weightlessness, motion sickness, pilot fatigue, discomfort from hunger or sleepiness due to the absence of the Earth’s day-and-night cycle, and psychological disturbances caused by confinement and isolation. These problems, however, are generally prevented by intensive preflight training in high-powered simulators and by careful design of equipment and spacecraft."