This book, one in the series on Aerospace Education III, deals with the general nature of human physiology during space flights. Chapter 1 begins with a brief discussion of the nature of the atmosphere. Other topics examined in this chapter include respiration and circulation, principles and problems of vision, noise and vibration, and self-imposed stresses. Chapter 2 provides an account of aerospace medicine. The next two chapters are devoted to a general description of protective equipment used by fliers, pilot training, and surviving and living in space. Chapters 5 and 6 provide information on skylab and future space flights. The book is designed to be used in the Air Force ROTC program. (PB)