Use of spacecraft data to derive regions on Mars where liquid water would be stable

Combining Viking pressure and temperature data with Mars Orbital Laser Alti meter topography data, we have computed the fraction of the martian year du ring which pressure and temperature allow for liquid water to be stable on the martian surface. We find that liquid water would be stable within the H ellas and Argyre basin and over the northern lowlands equatorward of about 40 degrees, The location with the maximum period of stable conditions for l iquid water is in the southeastern portion of Utopia Planitia, where 34% of the year liquid water would be stable if it were present. Locations of sta bility appear to correlate with the distribution of valley networks.