Volume II in the Space Biology and Medicine series, Life Support and Habitability addresses major issues and requirements for safe habitability and work beyond the Earths atmosphere. It is composed of two parts: The Spacecraft Environment and Life Support Systems. As in the first volume, the authors are specialists in their fields in the United States and Russian Federation. The book is intended for a widespread audience. In particular, it will appeal to students majoring in biomedical and technical subjects who intend to specialize in space science, engineers developing life support systems, and physicians and scientists formulating medical specifications for habitability conditions onboard spacecraft and monitoring compliance with them. There are more than 285 figures and tables and 1100 references.