2004 Annual Science Report
University of Colorado, Boulder Reporting | JUL 2003 – JUN 2004
Biogeochemical Cycling and Resources on Mars
We are exploring the geochemical energy that can support metabolism via chemical weathering at low temperatures on Mars. Such low-temperature environments may be widespread, based on recent discoveries and analyses pertaining to Martian gullies, sub-freezing liquid water, crater lakes, and depositional environments. Our results will be used to determine which types of geological environments are most suitable for supporting Martian organisms, and what the availability of energy as a resource is. To answer these questions, we have been using three different geochemical reaction modeling programs (EQ3/6, PHREEQC, and Geochemist’s Workbench). All three programs have been used to simulate the mixing of water with various host rock compositions based on Martian meteorites, to determine geochemical weathering pathways, and to estimate available energy that can support metabolism. Currently, we are using Geochemist’s Workbench to determine various weathering products and estimate available energy based on Gibb’s free energy, and have looked at three different reactions (the weathering of fayalite, ferrosillite, and magnetite) as an initial approach to the problem. For these three reactions, we have varied the temperature (0-25 degrees C), and looked at a range of H2 fugacities to determine which temperature and fugacity will produce the most energy. This allows us to determine the conditions that have optimal geochemical energy available to organisms.
In the near future, we will develop a reaction matrix that will include a wider range of possible reactants and products for Mars based on terrestrial analogs and what is known about Martian mineralogy.