THE DECISION OF THE UNITED STATES in 1958 to initiate a manned space flight program was based upon the confident assumption that technology could provide the life-support systems necessary for human survival in the hostile space environment. Primary responsibility for developing these flight systems obviously would rest with physical scientists and engineers. Bioastronautical exports, including flight surgeons who had long worked as a team with aeronautical engineers, believed from experience with conventional aircraft that man could sustain the combined stresses of space flight. It was believed that extension of the principles of traditional aviation medicine could provide the key to man's survival in the relatively short periods of space flight envisaged for Project Mercury. Thus, space medicine would represent basically an extension of aviation medicine.

Both inside and outside the newly created National Aeronautics and Space Administration, some scientists were concerned about specific biomedical problems of early manned space flight. Definitive biological experimentation had not yet laid a solid basis for such a mission, even though it was recognized that Project Mercury would be but a first step and would not involve the obviously novel biological hazards of extended space flight. Engineers could cope with the hardware required for orbital flight, but the astronaut was more than a mere component of a system. He also had become a symbol of the hope that man himself could perform in extraterrestrial space. The confidence of the aerospace medical community and the skepticism of the biological scientists were to come together in the working out of the first U.S. manned space flights.

NASA was charged by the President of the United States with carrying out a twofold mission in manned space flight. As a high national priority, ranking second only to national defense, NASA must at the earliest feasible time launch a man into space, provided with an environment in which he could perform effectively, and recover him safely. This was Project Mercury, with its relatively limited goal. Concurrently, NASA physical scientists and engineers, with the support of the Nation's leading life scientists, must develop a capability for extended manned space flight.

Project Mercury could not define the biological and life support problems that may be posed by extended space missions, particularly prolonged weightlessness. Mercury flight times were limited by spacecraft weights which, in turn, were restricted by the capability of available launch vehicles. The theoretical literature on such conditions as weightlessness and combined physiological stresses must necessarily await validation by future flights. The task assigned Project Mercury was to prove that man could survive and function usefully in space. That fact has now been established.

Whether or not the first U.S. manned space program, even with its limited goals, was worth the human risks involved was the subject of some debate within the scientific community. The final judgment must await the course of history. Some scientists are now seeking pilot ratings for future manned space flights, indicating their confidence in the more extensive flights that will take place in the near future.

The present document is an attempt to record the way in which the medical community in particular, and the life scientists in general, provided clinical support for Project Mercury and, as a corollary, contributed toward the evolution of the long-range manned space-flight program. It is primarily a study in management, for only through the careful planning and management of the Nation's resource—together with dedicated effort—could Project Mercury have been accomplished in such a short time. It is a record of which the Nation can be proud, for the first U.S. manned space flights were successful against great odd—odds such as any pioneering effort must always overcome.

W. Randolph Lovelace II, M.D.
Director, Space Medicine