A dedicated environmental simulator has been designed and built in order to recreate conditions at Mars’ surface in terms of atmospheric composition, temperature, pressure (Zurek 1993; Hourdin et al. 1993; Gurwell et al. 2005) and UV radiation (Cockell et al. 2000; Córdoba-Jabonero et al. 2005). The simulator consists of an environmental chamber (Figure 1) containing six capsules where the bacterial cells or spores are accommodated. Each capsule is interconnected with a 0.2 μm biological filter and a valve to the main chamber. This configuration makes possible the control of the atmospheric conditions inside the capsules, acting only on the main environmental chamber and allowing the extraction of a single biological sample without perturbing the other ones. The baseplate of the main chamber is equipped with a cooling and heating system for temperature control of all test samples together. The samples are illuminated through a quartz window with a UV lamp (180–300 nm) simulating the diurnal solar flux at Mars (Patel et al. 2004).

Figure 1
figure 1

Section and overview of SAM, the Martian Environment Simulator environmental simulator.

Full size image

During the tests, the biological samples are kept in a controlled atmosphere of a selected gas mixture (mainly CO2) and exposed to thermal cycles simulating daily and seasonal Martian cycles, with temperature ranging from −140°C to more than −20°C and pressure of the order of few mbar (Hourdin et al. 1993). Samples could be removed and changed at different phases of the experiment, for studying temporal variation of the survival.

The bacterial species selected for the experiments belong to the genus Bacillus, Deinococcus and Clostridium. The choice of Bacillus and Clostridium derives from their ability to produce spore, that give them a remarkable resistance to external conditions, while the Deinococcus survives to the exposure to ionizing radiation (even more than 1.5 Mrad), because of his ability to repair the breaks on the double chain of DNA restoring the chromosomic continuity. The metabolism and eventual protein synthesis of the biological samples will be analysed by microscopic electrophoretic and molecular methods.

We do expect these experiments to help for investigating the survival of extremophile lifeforms and prebiotic synthesis and degradation, and also to understand if the possibility of planetary contamination exists. These experiments will allow defining the limits of the lifeforms that may be present on Mars, either autochthonous or imported from Earth by our landers, and may provide hints on the origin of life on Mars.

The facility will also be available for collaborations with scientists of various fields (biologists, geologists, etc.) interested in performing experiments in very extreme environments, like that of Mars or of some regions of the Earth like Antarctica.