1ON THE EXISTENCE AND STABILITY OF LIQUID WATER ON THE MARTIAN SURFACE By Justin.Thompson Department of

Present-day Mars is thought to be a frozen desert on which liquid water is not likely to be found. The prevailing assumption has been that due to average temperatures below 273 K and atmospheric pressures at or below water's triple-point vapor pressure of 6.1 mbar, the existence of liquid water as an equilibrium phase at or near the surface is impossible at the present epoch. However, there is substantial evidence that liquid water has existed in the past and may presently still exist on or directly below the Martian surface. I conducted simulation experiments in the Andromeda planetary environmental chamber in order to investigate the stability of water under Martian conditions and its possible role in the subsequent formation of surface features on Mars. Results indicate it is possible for liquid water to exist in a metastable phase on the Martian surface for a time of weeks to months. Literature Review Present-day Mars is thought to be a frozen desert on which liquid water is not likely to be found. The prevailing assumption has been that due to average temperatures below 273 K and atmospheric pressures at or below water's triple-point vapor pressure of 6.1 mbar, the existence of liquid water as an equilibrium phase at or near the surface is impossible at the present epoch. However, there is substantial evidence that liquid water has existed in the past and may presently still exist on or directly below the Martian surface. The evidence comes from geological features seen on the surface of the planet and in Martian meteorites, geochemical analyses of Martian meteorites, and data returned from spacecraft which indicate the presence of ice at near surface levels of the Martian regolith (1, 15). Also, evidence for circulation of liquid water within the present Martian atmosphere has been observed (20)