Since liquid water is a basic ingredient for life, an important step in the search for life on Mars is to determine if liquid water ever existed there. The discoveries of evidence for interfacial water, for liquid saline water or brines, and perhaps for methane on present day Mars revived the possibility of extant microbial life in this nearby planet. The recent discovery of photometric and spectral evidence for liquid saline water on Mars leaves little doubt that liquid water exists, at least temporarily, today. In addition, it suggests that deliquescence occurs seasonally on Mars’ polar region. The goal of this session is to debate these discoveries and their implications as well as to report new findings related to liquid water on Mars.