In 2008 NASA¿s Phoenix Lander mission landed on the surface of Mars to complete physical and chemical analyses aimed at characterising the history of water and potential habitability of the Martian subsurface. The extreme temperatures found on Mars typically lead to either crystallization or evaporation of water, making it difficult to imagine how water could be found in liquid form. A surprising and intriguing finding from the Phoenix Lander mission was the discovery of the perchlorate ion ClO4-. Perchlorate is a strongly oxidised ion which lowers the freezing point of water substantially. Recent studies of the thermodynamic and kinetic properties of magnesium perchlorate solutions have determined the physical conditions suitable for the formation of liquid solutions. In this proposal we aim to provide the first structural insight into liquid water in in these intriguing solutions.