SILICA ON

MARS

In May 2007, the Spirit rover disturbed a patch of ground with its inoperative wheel, uncovering an area extremely rich in silica (90%).^[95]The feature is reminiscent of the effect of hot spring water or steam coming into contact with volcanic rocks. Scientists consider this as evidence of a past environment that may have been favorable for microbial life, and theorize that one possible origin for the silica may have been produced by the interaction of soil with acid vapors produced by volcanic activity in the presence of water.^[96]

Based on Earth analogs, hydrothermal systems on Mars would be highly attractive for their potential for preserving organic and inorganicbiosignatures.^[97][98][99] For this reason, hydrothermal deposits are regarded as important targets in the exploration for fossil evidence of ancient Martian life.