Exposure to space flight has been shown to results in changes in many physiological systems, including the musculoskeletal system, the cardiovascular system, the immune system, and the neurovestibular system. These changes could negatively impact the ability of humans to undertake long-term habitation and exploration of space. However, there are limits to the studies that can be done with humans in space. Both ground-based and space flight animal model systems are currently used for these studies as an alternative. This volume covers the latest developments in the use of animal models to study the effects of the space flight environment on human physiological systems. It includes unique insights into the mechanisms and the potential role of gravity, stress, radiation and other space flight environment factors on physiological systems. It includes a complete history back to the beginnings of space flight. It discusses the development of countermeasures to prevent any damaging effects of the space flight environment on physiological systems.