ABSTRACT Humanity is on the verge of having the capability of constructively directing environmental changes on a planetary scale. One could argue that we are making these changes on Earth today, but in a negative manner. Within the foreseeable future, we will have the technology to modify Mars' environment, and make it a habitable planet. However, we do not have enough information to determine the course of such an event. SHOT has designed and built a test-bed apparatus that can replicate most of Mars' environment conditions (with the notable exceptions of gravity and cosmic radiation) within a 5.6 liter chamber. Here, we present the results of initial experiments to determine the suitability of specific microorganisms as pioneering life-forms for Mars. Included among the potential pioneers were five genera of cyanobacteria (Anabaena, Chroococcidiopsis, Plectonema, Synechococcus and Syenechocystis), and three partially-characterized eubacterial strains that were isolated from Chile's Atacama Desert (two species of Bacillus and Klebsiella oxytoca). During these initial trials, we used a present-day mix of martian atmsospheric gases, but at a pressure of 100 mbar (10 times Mars's current atmospheric pressure). Organisms were inoculated into samples of JSC Mars-1 soil stimulant and exposed to full-spectrum simulated martian sunlight. Day/night temperature cycled from 26°C to -80°C and back. Experiments included a 24-hour, brief-exposure trial, a 7-day trial, a14-day trial and a 5-week trial to determine the survival and growth of our potential martian pioneers
