Anode Effects On Microbial Fuel Cell Efficiency M. Brant 3 , G. Chu 6 , M.W. Claire 2 , J. Curnutt 1 , E. Gomez 1 , A. Gonzalez 4 , C. Gott 4 , M. Grigsby 4 , R. Hovanesian, 4 G. Kaladjian 4 , J. Losch 3 , A. Nguyen, A. Olano 4 , G.W. Payton 4 , A. Razzak 4 , K. Rotunno 4 , S. Saleemi 4 , A. Scheppelmann 3 , K.E. Schubert 1 , G. Solis 4 , E. Statmore 5 , K. Symer 3 , 1 School of Computer Science and Engineering, California State University, San Bernardino, 2 Virtual Planetary Laboratory, University of Washington 3 California Polytechnic State University, San Luis Obispo 4 California State Polytechnic University, Pomona 5 San Francisco State University 6 NASA Ames Abstract— The use of microbial fuel cells to detect anaer- obes and power experiments in remote extreme environments is examined by a team of scientists and student teachers in a joint venture of the California State University system and NASA Ames. The economic viability of carbon fiber electrodes is tested by comparing their performance to graphite rods, which are commonly used. A connection between concentration of life and voltage output is indicated, which provides a potentially easy and powerful test for the presence of life in extreme environments such as found on Mars. Pollution free but low power density microbial fuel cells are shown to demonstrate viability as a power source for sensing applications. Keywords: Life in extreme environments, microbial fuel cell, life on Mars 1. Introduction Two great questions confront scientists working in astro- biology and extreme environments. The first is how to detect life outside our planet, and the second is how to power equipment in extreme environments. In this paper we suggest a potential solution to both problems. 1.1 Detecting Life in Extreme Off-world Envi- ronments Recent studies, see [4], have cast doubts on the inter- pretation of the 1976 experiments conducted by Viking, which indicate no life in the soil samples analyzed. The basic problem with Viking was that its experiments were destructive to organics, and required chlorine to be in a chloride salt form, when it turns out from Mars Phoenix Lander that chlorine is in perchlorate form. The new Mars Science Lab to be launched soon will hopefully clarify some of the results, but still the question remains as to what is a good way to detect life on another planet that has an extreme environment. Ideally, we would like to submit the samples to a wide range of tests, but this is economically not viable. Detection of life is dependent on the form the life takes, so to detect life with a minimum of equipment requires some assumptions to be made. We postulate a few simple ones. • First, if Mars had life, it was carbon based. Other elements like silicon has been suggested but we have no idea exactly what such a life would look like and thus it would be very hard to detect, and harder to prove. • Second, if Mars had carbon-based life, it likely had microbial life somewhat similar to earth. This is reason- able for a variety of reasons, including ease of forma- tion, durability, necessity in an ecosystem, possibility of cross-fertilization from impacts, and if not true it is unlikely we could guess the exact nature of life on Mars. • Third, if Mars had microbial life, it likely had a range of anaerobes, as the atmosphere likely had higher carbon dioxide and less free oxygen than Earth. • Finally, if Mars had anaerobes, metal reducing ones similar to Geobacter sulfurreducens were likely to exist, as they are widely dispersed on earth, and would fit the Mars well. Metal reducing anaerobes could be present in the ground of Mars, and could even still be alive in Martian lava tubes, which would provide a viable system for them to still survive. Testing for the presence of metal reducing anaerobes, is thus a logical step to verifying if Mars has or had life. 1.2 Powering Equipment in Extreme Environ- ments One of the greatest challenges of exploring extreme environments is the difficulty of finding long-term, self- sustaining, and indefinitely sustainable power sources for the kinds of equipment that may need to remain in place for extended periods under incredibly inhospitable conditions. In the case of a Mars rover, for example, scientists and engineers can leverage the power of the sun using solar panels to charge and recharge on-board batteries. In other situations anchored to the ground, wind can be harnessed to provide a renewable energy source. Underwater, near the deep ocean thermal vents, engineers and scientists can