Research report 2003 - Max Planck Institute for Chemistry
APXS results reveal traces of the water-rich past of planet Mars
SummaryThe two NASA rovers "Spirit" and "Opportunity" are currently successfully exploring their landing sites Gusev crater and Meridiani Planum on Mars. On board are two Alpha-Particle-X-ray-Spectrometers (APXS), which determine in-situ the chemical and mineralogical composition of rocks and soils. The chemistry of the analyzed surfaces clearly provides evidence for a water-rich past on planet Mars. The volcanic rocks at Gusev crater are covered by a rind and are penetrated by veins that are enriched in elements, e.g., sulfur, chlorine and bromine, which occur as anions in water. The chemistry of the old rocks at the Columbia Hills is altered to such an extent that their indigenous composition is difficult to deduce. The Meridiani Planum landing site exhibits bedrocks which consist of sulfates of up to 40 percent by weight. They were possibly deposited under conditions similar to those encountered presently in desert areas of the Earth.