Space
medicine is the branch of medicine involved in protecting human beings from the environment of space and, at the same
time, studying their reactions to that environment. The foundations of space
medicine can be traced back to aviation medicine, and the term aerospace medicine has evolved to encompass activity in both areas. Aerospace medicine has been a certified subspecialty of the American Board of Preventive Medicine since 1953. In addition to physicians, however, engineers, veterinarians, dentists, nurses, physiologists, psychologists, bacteriologists, toxicologists, pharmacologists, and biochemists also work in the field of space medicine. Specialists in space medicine are involved in all aspects of
spaceflight, from spacecraft design and crew selection to flight operations and postflight review.EARLY HISTORYThe early history of spaceflight was characterized by deep concern on the part of many scientists that humans would not be able to withstand the rigors of spaceflight, especially during launch and reentry, and might not be able to function usefully in space. As a result of this concern, the United States flew a number of monkeys aboard captured German V-2 rockets between 1948 and 1952. These early flights provided some launch and reentry data on comparable life forms and demonstrated the need for effective and reliable life-support systems. Between 1949 and 1956 the Soviet Union flew 15 similar flights using dogs, some flights reaching an altitude of 213 km (132 mi). A dog named Laika was then launched aboard Sputnik 2 on Nov. 3, 1957, and orbited the Earth for seven days until she was finally euthanatized. Between 1958 and 1961 the United States flew monkeys in several suborbital and orbital missions. These flights showed that pulse and respiration rates, blood pressure, and performance of specific tasks for which the monkeys had been trained were basically unaffected by spaceflight.On Apr. 12, 1961, the Soviet cosmonaut Yuri Gagarin demonstrated for the first time that human beings could safely orbit the Earth. His flight confirmed a U.S. decision to use humans rather than animals on succeeding spaceflights. The U.S. program proceeded cautiously, however, by gradually increasing the exposure time of humans in space and by carefully observing and reviewing the effects of each flight. The six U.S. astronauts who flew on Project Mercury (see Mercury program) between May 1961 and May 1963 returned in good health, and as a result, many of the earlier medical concerns about spaceflight were dispelled.