Planetary underground tool (pluto) for future astrobiological missions to Mars

While Viking did not find any certain evidence of life or organic material, there is good reason to believe that at depths of a few metres organic material exists whose external or biological origin could be investigated by analyses of in situ soil samples. A prerequisite for such experiments is the equipment of the lander/rover with a device aimed at taking samples from various depths of subsurface. The prototype of such a device is the Planetary Underground Tool (PLUTO) which is part of the payload of the ongoing exobiological Beagle 2 lander of ESA's Mars Express mission. PLUTO is a regolith-penetrating, tethered "Mole" intended for acquisition of several subsurface soil samples from depths between about 10 cm and approximately 1.5 m. PLUTO onboard Beagle 2 is equipped with a sampling device and a temperature sensor, and the analysis of carbon isotope ratio and organic molecules will be performed on the surface of Mars by the Gas Analysis Package (GAP). In future missions some instruments relevant for astrobiology could also be accommodated directly within the PLUTO such as a compact detector head on a fibre-optic cable for underground deployment to search for biota of biogenic materials whilst concurrently characterising the mineral habitat.