Monday, September 25

Showtime: 7:00 PM

Chautauqua Community House

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The oldest areas on Mars’ surface are also the most heavily cratered, with characteristics comparable in some ways to the ancient battered highlands of the Moon and Mercury. Intense early cratering by comets and asteroids affected Mars by melting and fracturing its crust, draping large areas in impact ejecta, which generated regional-scale hydrothermal systems, and increased atmospheric pressure (and thereby, temperature) to periodically re-start an otherwise unspectacular hydrological cycle. Research has found that between 10 and 100% of the oldest Martian surface was covered by impact craters and blanketed in resultant (hot) ejecta. If the earliest history of Mars was defined by arid and cold conditions, impact-induced heating punctuated this surface state by melting near-surface water ice to generate regional-scale hot spring systems. Thus, rather than being harmful to the possible early Mars life, the intense early impact environment instead enhanced the volume and duration of its surface/subsurface crust for the first living things to take hold.

Speaker: Dr. Stephen (Steve) J. Mojzsis is a professor of geology and director of the Collaborative for Research in Origins (CriO) in the department of Geological Sciences at the University of Colorado at Boulder. His fields of interest include geobiology, geochronology, cosmochemistry; crustal evolution, evolution of atmospheric oxygen and origin of biogeochemical cycles.

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