This book is a translation of the collective work of a group of American scientists, which include such well-known specialists in the field of rocketry and astronautics as K. Ericke, J. Irving, J. Sutton, R. Bassard and others. The book is based on material from a course of lectures given by the authors in the summer of 1957 at the University of California, and covers a number of problems related to the design of spacecraft, analysis of their movement and with motion control tasks.