The small Martian environment simulators they built (pictured top), called LISA and mini-LISA (Laboratorio Italiano Simulazione Ambienti), make an attempt at duplicating Martian surface conditions.
Inside the mini-Mars habitats, temperature ranges from a maximum of near-freezing in the tropical Martian summer to –200 degrees Fahrenheit (-130°C) in the harsh polar winter. Air pressure is kept at an anemic fraction of a percent of Earth's surface pressure. The bottled atmosphere is 95 percent carbon dioxide with trace elements. Searing ultraviolet (UV) light floods the habitat.
What's handy is there are no time limits on the experiments. The mini-Mars world is refueled with liquid nitrogen weekly to keep it chilly.
Experiments to date show that some bacteria strains can survive the freezing temperatures, low pressure and bone-dry atmosphere. Without water, the bacteria suspend their metabolism and build endospores, dormant non-reproductive structures with a thick wall for protecting DNA.
But UV light is a bug-killer after just a few minutes of exposure. When UV light is removed from the mini-lab - to simulate could happen during the night or in the shadow of rocks - the spores appears to remain stable, say the researchers. The spores become activated again when liquid water is added.
The team simulated the dust coverage that's common on Mars by blowing on the samples with grains of volcanic ash from Etna Volcano eruptions, or red iron oxide dust used in industrial color production. This UV insulator allowed the bacterial to survive for longer periods.