THE HUNT FOR LIQUID WATER, LIFE AND LANDING SITES ON THE SURFACE OF MARS TODAY
Contributors: Vincent Chang, David Chu, Christina Lee, Robert Lee, Dalziel Wilson, and Miki Yamada
Teaching Staff: Larry Kuznetz and David Gan
University of California, Berkeley
"Liquid water does not exist on the surface of Mars...Without liquid water, life as we know it cannot exist." Principal Viking investigator Norman Horowitz made these statements over two decades ago, establishing the contemporary paradigm of a barren Mars today. Since that time, a wealth of new knowledge has been accumulated in the form of images and data on soil, air composition and climate from the robotic probes of the 90s, Pathfinder and Mars Global Surveyer (MGS). We now have extensive pressure and temperature data from all three probes (Figure 1a and Figure 1b) demonstrating pressures above the triple point and temperatures above freezing for long periods of time, meeting the criteria for liquid water. Pathfinder also found 20íC variations along its mast, suggesting ice can melt on the surface even with air temperatures above it below freezing. Spacial variations in temperature may also permit ice to melt against sunlit, smooth, dark rocks despite immediately adjacent temperatures being below zero. Other issues of concern include boiling, evaporation and stability. Under observed Martian pressures, there exists only a 7íC window exists between freezing and boiling. Though narrow, the Viking orbiter observed such a window. As for stability, even if liquid water could exist, skeptics argue, it would be rapidly driven off by high evaporation rates into the dry atmosphere. On the other hand, frost was observed to persist at Viking s Utopia Planitia landing site, implying condensation and stability.
As the debate rages on about past or present life on Mars, the prevailing assumption has been that the liquid water essential for its existence is absent because pressures and temperatures are too low. This study presents data, anecdotal and experimental evidence to challenge that assumption.