Jesse Tarnas
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subsurface habitability

PictureKidd Creek Mine, 2.4 km underground, sampling billions-year-old groundwater. Photo Credit: University of Toronto Stable Isotope Laboratory
Subsurface microbial communities on Earth harness redox reactions to drive their metabolisms --sometimes in groundwaters older than a billion years. I am interested in how the chemical energy sources for redox reactions--oxidants and reductants--are produced within the crusts of terrestrial planets such as Earth and Mars.

Our research has demonstrated that radiolysis generates sufficient redox energy to sustain a modern martian biosphere where groundwater is present in the subsurface. We have also shown that ancient Mars likely hosted a long-lived habitable subsurface environment that microbes could have existed in. The deep subsurface of Mars is longest-lived and most stable habitable environment on the planet, and may host life today if groundwater still exists there. 
​I am enthusiastic about future missions to study the subsurface of Mars via electromagnetic sounding and drilling, with an eye towards searching for extant subsurface life.

We are currently investigating the varying rates at which methane is produced in ancient groundwater in Earth's deep subsurface, which has been separated from the surface hydrological cycle for millions to billions of years. Answering this question on Earth will allow us to determine how abiotic methane production would have affected the evolution of Mars.


Remote sensing of Mars

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Hyperspectral data of Mars has allowed us to detect mineral distributions that inform our interpretations of the planet's geologic history. I use this data, along with high-resolution images, to detect new minerals and determine the types of environments that they formed in --including evaluating the habitability of those environment. We have detected hydrated silica in Jezero crater--landing site of the Perseverance rover--which is exciting due to its high biosignature preservation potential. 


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