Reactions between Fe-bearing rocks and circulating waters power significant electron flow that can be harnessed for microbial metabolism and growth deep beneath the surface of the Earth. I am a geomicrobiologist who develops and apply x-ray scattering and spectroscopic approaches to interrogate the redox reactions that occur between mineral surfaces, microorganisms and fluids. My lab conducts experiments in field settings with access subsurface rocks and waters, and identify favorable interfaces for biologically-induced mineral dissolution, microbial growth and biomineralization processes. This information is then used to predict the distribution and activity of rock-hosted biological communities on Earth, and to guide the search for past or present extraterrestrial life on other rocky planets in our solar system.