Description/Abstract Our laboratory has recently been studying life in extreme salt environments. Using a newly established lab at 1.1 km depth in the Boulby potash mine, UK, we have been able to study how life persists in deep, dark hypersaline environments, showing that communities may use diverse carbon sources in the deep subsurface. Simulations of Martian brines have allowed us to study the habitability of geochemically very different salt solutions on the surface of Mars and establish new understandings of the limits of life. In addition to answering science questions, we have been using these environments to test new technologies for the robotic and human exploration of Mars.