Page:Concepts for detection of extraterrestrial life.djvu/18

8 in response to the changing Martian environment, would have produced organisms quite different from those which now inhabit Earth.

Experiments have been performed in which terrestrial micro-organisms have been introduced into simulated Martian environments, with atmospheres composed of nitrogen and carbon dioxide, no oxygen, very little water, a daily temperature variation from +20° to —60° C, and high ultraviolet fluxes.