Studies of the effects of simulated Martian environments on sporeforming anaerobic bacteria were carried out by Hawrylewicz et al. ([ref.49]). They showed that the encapsulated facultative anaerobe, _Klebsiella pneumoniae_, survived under simulated Martian atmosphere for 6 to 8 months, but were less virulent than the freshly isolated organisms. Spores of the anaerobe _Clostridium botulinum_ survived 10 months in the simulator. Hagen et al. ([ref.53]) found that the addition of moisture to dry-simulated Martian soil did not improve the survival of _Bacillus subtilis_ or _Pseudomonas aeruginosa_. _Bacillus cereus_ spores survived, with added organic medium plus moisture, but no germination of the spores resulted. Hawrylewicz et al. ([ref.49]) put rocks from Antarctica bearing various lichens in simulated Martian conditions in a large desiccator. They found that the algal portion of a lichen, _Trebouxia erici_, showed only slight resistance to the Martian environment. They also pointed out the effect moisture had on the physical condition of lichens. The undersurface of a lichen has great water-absorbing capability, and the slightest amount of moisture on a rock surface is absorbed by the lichen which can turn green in 15 minutes. Scher et al. ([ref.51]) exposed desert soils to simulated environmental conditions and diurnal cycles of Mars. The atmosphere consisted of 95 percent nitrogen and 5 percent carbon dioxide (no oxygen) and was dried, using calcium sulfate as a desiccant. The total atmospheric pressure was 0.1 atm. The temperature ranged from -60° to +20° C in 24-hour cycles. One hour was spent at the maximum and at the minimum temperatures. The chambers were irradiated with ultraviolet, 2537 Å, with a dose of 10⁹ ergs/cm², which is comparable to a daily dose found on Mars, and easily exceeds the mean lethal dose for unprotected bacteria. Soil aliquots were removed weekly and incubated at 30° C. The scoring was done both aerobically and anaerobically. Sporeforming obligate and facultative anaerobes, including _Clostridium_, _Bacillus_, and _Planosarcina_, and nonsporeforming facultative anaerobes, including _Pseudomonas_ and _Rhodopseudomonas_, were found. The experimental chambers were frozen and thawed cyclically up to 6 months. Organisms that were able to survive the first freeze-thaw cycle were able to survive the entire experiment. The ultraviolet irradiation did not kill subsurface organisms, and a thin layer of soil served as an ultraviolet shield. All of the samples showed survivors.