The study of geomorphological or geologically relevant planetary environments on Earth with a certain increased irradiation income (e.g. UV radiation), very low or very high temperatures and very dry conditions is prerequisite for the search of microorganisms in such niches which might have a chance or even might be able to live in extra-terrestrial environments such as e.g. the planet Mars. The study of life’s activity in the field as well as in the lab and under simulated planetary conditions is important for searching for the right “biosignatures” and “biotraces” on these other worlds and for classifying other planets as habitable for terrestrial life forms or as objects which are inhabitable. Tests for instruments with a potential to detect life in such kind of environments are foreseen in the near future.