The ecology of micro-organisms in a closed environment.

Experimental data are presented which have a bearing on the susceptibility of astronauts to infectious diseases. These experiments include the observation of growth by two bacteria in Biosatellite 2, in which higher mean densities were attained than in earth-based controls. In addition, weightlessness combined with the special environment of a space vessel may affect the physiology of the astronauts. Earth-based studies in closed chambers were carried out under a variety of conditions with regard to pressure and oxygen content. One notable result was the transfer of micro-organisms from subject to subject. Comparative experiments were carried out in Antarctica and it was shown that the tests in closed chambers differed markedly from the Antarctica experience. The objectives and procedures of microbiological tests of the Gemini and Apollo programs are outlined.