[24]

THE STABILITY OF LIQUID WATER IN POROUS ROCKS IN A MARS-LIKE ENVIRONMENT.   C. Paty¹, C. McKay², D. Catling³, J. Heldmann⁴. ¹Physics and Astronomy, Bryn Mawr College, PA, ²PhD AstroGeoPhysics, University of Colorado, ³PhD Atmospheric, Oceanic and Planetary, Physics, University of Oxford, ⁴MS Space Studies, University of North Dakota.

On Mars today, low temperature and pressure limit the stability of liquid water. The effects of pore sizes and atmospheric pressure on liquid water in rocks were studied to examine the possibility of liquid water existing on Mars inside rocks and in pore spaces in the soil. Porous rocks from the Antarctic and from the Negev Desert (Israel) were used along with the simulated Mars dirt JSC Mars-1 and a control material of known pore size distribution. The relationship between relative humidity and the water-containig pore size in equilibrium (i.e. not evaporating) was determined by placing the samples in salt solution controlled relative humidity chambers and measuring their water mass at equilibrium. The relationship between atmospheric pressure and water stability in pores was then determined by placing the same samples in a pressure chamber with only water vapor present on a scale and measuring their water mass at equilibrium. Due to the effects of small pores on the surface tension, and hence the vapor pressure, of water, it is possible that the temperature and pressure requirements for liquid water stability in pores are significantly different than those for flat surfaces.

(Supported by the NASA Ames Astrobiology Academy.)