Building Worlds Seminar (online): Lessons from Hot Springs on Earth Applied to the Search for Traces of Life on Mars

Ancient hot spring deposits have long been recognized as key exploration targets in the search for past life on Mars because they are known on Earth to harbor microbial life and preserve traces of it in the rock record.  They also are recognized as a possible cradle of life on Earth, adding to the importance of finding hot spring settings on Mars.  In 2007, the Mars Exploration Rover Spirit encountered outcrops and soil composed of nearly pure opaline silica (amorphous SiO2*nH2O) in the Columbia Hills of Gusev crater.  Such materials commonly form around hot springs, but geochemical observations were used in this case to discount this possibility.  Years later, following the recognition that a suite of features from terrestrial hot spring settings is evident at the Spirit site, the case for hot spring deposits there is robust.  Among the features are possible traces of life preserved in the opaline silica rocks, which was not recognized during the operational lifetime of the rover. Consequently, this provocative scenario remains untested.

Biography:
Steve Ruff is a planetary geologist with a focus on the mineralogy of Mars determined via infrared spectroscopy, part of an effort to understand its geologic history and potential for past habitability. Terrestrial field work and lab studies are an integral part of this effort, providing an empirical basis for interpreting data from orbiting spacecraft and rovers. He has been an active member in several Mars missions and a participant in the planning of future missions.

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