Martian Geochemical Applications with FREZCHEM

Affiliation(s)PIProject periodFunded by
DEES Marion, Giles M 06/15/2009 - 06/14/2013 National Aeronautics & Space Administration

Project Summary

NASA's mission is driven, in part, "to explore the Universe and search for life." In this project, we will address scientific questions such as:

"Can hydrothermal environments account for massive silica deposits and other alteration mineralogies on Mars?"

"How might hydrothermal systems on Mars differ from those on Earth, where on Mars impact, volcanic, and other geo-hydrothermal systems may involve little meteoric water but abundant dissolved salts, less granite and more mafic/ultramafic rock, possible abundant condensed CO2 (liquid CO2, solid CO2, or clathrate hydrate CO2), and more extreme temperature gradients into cryogenic conditions?"

"Can massive gypsum deposits in the north polar region be explained by a quantitative geochemical model that is a function of temperature, pressure, and chemical composition?"

"What is the influence of SO2, H2S, SO3, and SO4 chemistries on the Martian surface environment, climate, and mineralogy?"

"How important are acidic iron minerals like jarosite, and alkaline minerals like zeolites and phyllosilicates in controlling surface acidity on Mars?"

"What roles do temperature, pressure, and chemical composition play in controlling potential habitats for life on Mars?"

Recent Mars missions have implicated hydrothermal systems and sulfur chemistries as important geochemical drivers across a wide range of Martian sites (e.g., Arabia Terra, Gusev Crater, Juventae Chasma, Meridiani Planum, and Valles Marineris). Also, alkaline soils (pH = 8-9) were found at the Phoenix lander site.

For the past decade, NASA has funded the development of the FREZCHEM model. FREZCHEM is parameterized for broad ranges of temperature ( 25°C), reduced-sulfur chemistries, and some alkaline mineral chemistries.

In this projectl, we will:

(1) extend the validity of FREZCHEM to 95?C for hydrothermal systems

(2) integrate SO2, H2S, and SO3 chemistries into FREZCHEM, and apply the model for

(3) hydrothermal environments

(4) strong acid chemistries

(5) massive silica depositions

(6) north polar gypsum depositions

(7) alkaline mineral formations on Mars.

These applications will also examine the prospects for life on Mars constrained by a wide-range of chemical compositions and temperatures. A great deal of speculation in planetary geochemistry is due to a relative paucity of solid geochemical data for extraterrestrial bodies. Until extraterrestrial samples are routinely returned to Earth, this limitation will remain. Herein lies the value of theoretical models such as FREZCHEM. Theoretical simulations based on sound chemical thermodynamic principles enable us to constrain potential mechanisms, to sharpen our focus onto more probable scenarios, and ultimately to sharpen our understanding of planetary geochemistry.