The low average temperature and low water activity of the Martian near-surface environment makes it challenging for living organisms to persist and propagate. Nonetheless, recent mission results indicate that environmental conditions exceed locally and temporarily the lower thresholds for life to exist. Furthermore, specific soil minerals, or combinations thereof, appear to provide a suitable habitat for microbial life, especially if associated with low-temperature brines or hygroscopic salts. Thus, a quantitative understanding of the habitability potential of the Martian near-surface environment, past and present, is very much needed and the focus of this proposal. To achieve this objective, we will test different types of soils and some of Earth’s hardiest organisms, using them as models (‘Mars-analogues’), to see if they can survive and perhaps even grow under the various environmental stresses known to exist on Mars. A major tool of our laboratory investigations will be the experimentally proven state-of-the-art Mars Simulation Chamber at the German AeroSpace Center, to which various soils materials and microorganisms will be exposed. The planned experimental investigations and models will be concurrently updated by analyzed mission data, particularly from landers and rovers (e.g., Curiosity Rover), to adjust our work to the newest Martian geochemical and environmental data available. Results from our proposed work will timely provide critical scientific knowledge to interpret incoming data from ESA’s ExoMars mission, which is scheduled for launch in 2016/2018. As one important deliverable of our work we will also construct a Mars Soil Analyzer, an instrument which will be designed for a future mission to Mars with the objective to achieve Technology Readiness Level 6 at the completion of the proposed study.