Could microbes on Phoenix survive on Mars? New Scientist

The Phoenix lander may have been coated with dozens of species of bacteria when it left Earth โ€“ and some may be hardy enough to scrape by on Mars, two new studies suggest.
But researchers say the parts of the lander that will contact water ice on Mars โ€“ which might provide a toehold for life โ€“ have been carefully sterilised, minimising the chances that terrestrial life could colonise the planet.
NASA has long realised that spacecraft could potentially seed other planets with terrestrial life. To cut the chances of transporting microbes to space, probes such as Phoenix, which landed on the northern plains of Mars on 25 May, are now assembled in clean rooms ventilated with filtered air.
NASA also swabs the craft to measure the levels of particularly hardy spore-forming bacteria, which can lay dormant for decades and withstand extreme temperatures.
But the agency doesn’t routinely check for less resilient bacteria or microbes that can’t be cultured, since harsh ultraviolet radiation on Mars is thought to quickly kill most such organisms.