“We knew before that any life would have an incredibly hard time to survive on the surface, and this study experimentally confirms that,” Dirk Schulze-Makuch, an astrobiologist at Washington State University who was not involved with the study, tells Popular Science.
Jennifer Wadsworth, a University of Edinburgh postdoc, and her adviser, astrobiologist Charles Cockell, subjected Bacillus subtilis, bacteria that commonly contaminate spacecraft, to Mars-like conditions in the lab. They found that when the microbes were exposed to perchlorates and then intense UV radiation, they all died within 30 seconds. Bacteria that were only exposed to the UV radiation died within 60 seconds. The bacterial cells fared a bit better when the researchers included silica disks, which simulated rocks, in the experiments.
This may mean that any microbes that existed on Mars when the planet harbored liquid water would have had a pretty tough time surviving, at least at the surface. “We don’t know exactly how far reaching the effect of UV and perchlorate would penetrate the surface layers, as the precise mechanism isn’t understood,” Wadsworth tells MailOnline. “If it’s the case of altered forms of perchlorate (such as chlorite or hypochlorite) diffusing through the environment, that might extend the uninhabitable zone. We may have to dig a little deeper to find a potential habitable environment.”