This article reviews current challenges to health in space and has a secondary intention to set the tone for this special supplement on 'Extra-Terrestrial Neurosciences'. The effects of microgravity, radiation, isolation, disturbance in circadian rhythms and the hostile environment on the cardiovascular, neurological, immunological and various biological human systems are discussed here. Alterations in physiology, environmental hazards, and mitigative safety measures are briefly discussed along with challenges encountered in providing remote diagnoses and health care during space missions.
Keywords: Health in outer space; space medicine; space travel.