Researchers from the University College London have suggested in a new paper published January 30th (in the journal Geophysical Research Letters) that finding life on Mars will require deep drilling in choice locations. Because the planet lacks sufficient atmosphere to ward off harmful radiation, there is no chance that microbes could have survived on the surface or even relatively deep within the ground. The researchers estimate that only microbes that have been buried several meters below the surface could survive, but finding such deeply hidden evidence is a task beyond the scope of any hardware presently on Mars. There is a chance that the European Space Agency's ExoMars mission (due to land 2013) could get deep enough, but what we really need are human hands. The new research looked at a number of different soil configurations, to estimate the best likely place to look: dry soil, frozen soil containing layered permafrost, and ice. Ice turns out to be the best medium, with a particularly good target identified as the frozen sea at Elysium, which is thought to have surfaced in the last five million years. Such a geologically young feature will not have received as much radiation as other older areas of the planet, thus increasing the likelihood of some microbes surviving.