New research suggests that the Martian surface may contain a toxic chemical compound called magnesium perchlorate, which destroys bacteria when exposed to ultraviolet light  The researchers exposed Bacillus subtilis to short-wave ultraviolet radiation, in conditions similar to those on the surface of Mars, and found that magnesium perchlorate is highly bactericidal, meaning it can potentially kill all bacteria  Bacillus subtilis loses viability within minutes as long as magnesium perchlorate is present  At the same time, the researchers found that two other substances on the Martian surface, iron oxide and hydrogen peroxide, were combined with magnesium perchlorate to enhance their germicidal properties by a factor of 10  This finding shows that the Martian surface is very dangerous for cells
In the long run, it may have an impact on subsequent Mars exploration, especially it may greatly increase the cost of human development of Mars
Magnesium perchlorate has miraculous effect on killing Bacillus subtilis