This is a book about the dynamics of spaceflight and the role of the cosmonaut in the man-space-craft system.The authors discuss the changes that take place in environmental conditions and, accordingly, in the psychophysiological mechanisms of space and time perception when man emerges into outer space. They consider the effects of weightlessness, prolonged isolation confinement, emotional stress, and other spaceflight factors on the human perception of time.There is also a description of the sensations experienced by one of the authors, the cosmonaut Alexei Leonov, on stepping out of his spacecraft in orbit.The authors suggest methods of cosmonaut training in space orientation for prolonged spaceflights and consider how work and leisure should be arranged aboard interplanetary spacecraft.This book is intended for all who are interested in aerospace medicine.