Polar bio-niches as Mars analogue environments

Mars, the red planet and neighbor of our planet Earth is defined to be at the rims of the habitable zone in our solar system. Previous and recent results from a variety of space missions with probes like the orbiter Mars Express, Lander devices as e.g. Viking, Phoenix and the rovers Pathfinder, Spirit and Opportunity enlarged our knowledge fundamentally about the nature of the red planet. It is postulated, that in the evolution of Mars water was liquid before 3.5 Billion years with a time range of about in maximum a couple of some million years due to a higher density of the atmosphere. In this time frame life started its evolution on Earth. Nowadays Mars is a cold and desert planet with high solar radiation income (including UVR) and a low density atmosphere of about 6 mbar. The atmosphere is dominated by 95 % CO2. Except of its dryness certain amounts of humidity are reaching even 100 % relative humidity and also the liquid phase near the soil surface. These high humidity conditions depend on the locations in latitudes, the radiation, the day cycles, the seasonal cycles and the mineral and salt content in the martian soil. The question still exists if life had the chance in the past to originate and to evolve on the red planet and if life might exist till recent times due to adaptation processes and form a kind of cryptic existence. Micro niches on Earth in polar and high mountain regions are mainly described as Mars analogs because of similar surface features and mineral composition. Studies in the field and Mars simulation experiments with microorganisms living in these polar environments are presented and might lead to conclusions that Mars is even today a habitable planet for polar terrestrial microorganisms