Mars Mineralogical Update--More Clays and Water

摘要

The search for life beyond Earth has motivated much of space exploration. Since life depends on water, the directive "follow the water" has guided NASA's exploration of Mars. In recent years, spacecraft orbiting the Red Planet have uncovered growing evidence for the presence of water, past and current, for example in now-dry river channels and deltas, the polar ice caps, ice buried in soils, and in various hydrated minerals. Clays and other sheet silicate minerals are potentially the most important, since on Earth clay minerals form by chemical weathering of rocks in the presence of water and are the major constituents of sedimentary rocks like shales and mudstones. However, clays can also form by hydrothermal alteration. The OMEGA imaging spectrometer on board the European Space Agency's Mars Express had previously detected clay minerals, chiefly nontronite, montmorillonite, and chlorite, in several locations (Poulet et al., 2005; summarized in Gornitz, 2006, 2008).