Planet Mars past environmental conditions were similar to the early Earth,
but nowadays they are similar to those of a very cold desert, irradiated by
intense solar UV light. However, some terrestrial lifeform showed the
capability to adapt to very harsh environments, similar to the extreme
condition of the Red Planet. In addition, recent discoveries of water in the
Martian permafrost and of methane in the Martian atmosphere, have generated
optimism regarding a potentially active subsurface Mars' biosphere. These
findings increase the possibility of finding traces of life on a planet like
Mars. However, before landing on Mars with dedicated biological experiments, it
is necessary to understand the possibilities of finding life in the present
Martian conditions. Finding a lifeform able to survive in Martian environment
conditions may have a double meaning: increasing the hope of discovering
extraterrestrial life and defining the limits for a terrestrial contamination
of planet Mars. In this paper we present the Martian environment simulators
LISA and mini-LISA, operating at the Astronomical Observatory of Padua, Italy.
They have been designed to simulate the conditions on the surface of planet
Mars (atmospheric pressure,0.6-0.9 kPa; temperature from -120 to 20 {\deg}C,
Martian-like atmospheric composition and UV radiation). In particular, we
describe the mini-LISA simulator, that allows to perform experiments with no
time limits, by weekly refueling the liquid nitrogen reservoir. Various kind of
experiments may be performed in the simulators, from inorganic chemistry to
biological activity. They are offered as experimental facilities to groups
interested in studying the processes that happen on the Martian surface or
under its dust cover.Comment: This paper should be published in the Proceedings of IAU Symposium
269, "Galileo's Medicean Moons: Their impact on 400 years of discovery",
printed by Cambridge University Press, but for an error of the editors was
not included in the printed versio