Figure 3: Maximum achievable water activity and corresponding temperature of calcium perchlorate brines.

To better resolve the habitability of the most favorable liquid case, here the (a) maximum water activity achievable by brines formed through deliquescence of calcium perchlorate is shown along with the (b) corresponding brine temperature. The latitude range is restricted to non-polar regions. The background is the gray-scaled, shaded relief map of Mars based on MOLA data.