Planetary Science Archives - Earth, Environmental, and Planetary Sciences

Sean Fettrow

Sean Fettrow is an Assistant Professor in the Department of Earth, Environmental, and Planetary Sciences at the University of Tennessee. His research involves understanding how global climate change alters land-atmosphere exchange of carbon. His work integrates field observations, greenhouse-laboratory experiments, and interdisciplinary biogeochemical analyses to understand how disturbances such as wildfires, permafrost thaw, sea-level rise, and land-use change influence the movement and transformation of carbon and other elements throughout the critical zone. By examining the links among soils, vegetation, and biogeochemical cycles, his research seeks to improve predictions of ecosystem responses to a rapidly changing climate and identify mechanisms that regulate ecosystem greenhouse gas uptake and emission.

In addition to advancing fundamental understanding of Earth system processes, Fettrow is committed to developing interdisciplinary collaborations that connect biogeochemists, geologists, hydrologists, ecologists, and environmental chemists. His teaching also emphasizes active learning, quantitative problem solving, and critical evaluation of scientific literature, with the goal of helping students build both technical expertise and scientific independence. He is particularly interested in providing students with authentic research experiences that bridge classroom concepts with real-world environmental challenges while preparing the next generation of Earth scientists.

Robert Jacobsen

Chris Fedo

Mars & Mars Analog Research

Chris Fedo has two major directions that I am working on and plan to develop in the future. First, in collaboration with Hap McSween, he is working on the textural and compositional evolution of martian soil. Despite the reserch community making some interesting advances on this topic, a number of problems remain, including mass-balancing weathered products with known surface and rock compositions on Mars. He is interested in understanding how the effects of chemical weathering and sorting during transport can impact soil composition. His terrestrial research on the early Earth and weathering and provenance plays a central role in helping him better frame problems on Mars where conditions during the Noachian may have been similar to Hadean and Archean Earth.

Second, he is interested in interpreting sedimentary environments on Mars using a mix of remote sensing and lander data.

Jarunetr (Nadia) Sae-Lim

Jarunetr (Nadia) Sae-Lim studies how hydroclimate, environments, and societies interact through time, with particular interest in monsoon regions and water-sensitive landscapes. She uses paleoclimate proxies, biomarkers, organic and stable isotope geochemistry, and climate and lake models to reconstruct past climate and environmental change. Her work connects long-term climate variability, wildfire disturbance, lake water quality, and human-environment interactions to inform current and future climate risk, ecosystem change, and societal resilience.

Hairuo Fu

Jill Mikucki

The Mikucki lab studies the interactions between microbes and their environment and how the impact of microbial metabolism is detectable on an ecosystem scale. Subglacial environments serve as our “model” ecosystem because their isolation and relatively simple food-webs allow for the study of microbially-mediated processes, which can be difficult to identify in more complex ecosystems.

Ice covers approximately 10% of the continental landmass on the planet making subglacial environments an important, yet poorly understood component of the Earth system. Subglacial aquatic environments serve as analogs for past global glaciation events, inform exobiological exploration, yield novel microorganisms for diversity studies and biotechnological advancement and will help us understand life’s ability to persist in cold and dark isolation for extended periods of time. Direct sampling of subglacial environments is tricky and microbial inhabitants grow slowly making the detection of in situ processes challenging. Thus, our work is highly collaborative and we employ a diversity of tools- from remote sensing to isotope geochemistry and culture and molecular microbiology. Clean access is a priority in these pristine systems and an important aspect of our work includes methods to monitor and insure clean sampling.

Research in the lab is guided by the following themes:

diversity and structure of microbial communities
linkages between microbial energetics and contemporary and ancient geochemistry, and
selection of microbial species and physiologies in extreme environments.

Currently funded projects in the laboratory include the exploration of Antarctic subglacial aquatic systems beneath the Whillans Ice Stream in West Antarctica and the mysterious Blood Falls subglacial ecosystem in the McMurdo Dry Valleys.

Manuel Scharrer

Manuel Scharrer, the David McDonald Endowed Assistant Professor in Critical Minerals, is an economic geologist, geochemist, and calorimetrist whose interdisciplinary research integrates petrology, mineralogy, geochemistry, and experimental thermodynamics to understand ore-forming processes and the behavior of critical materials.

His work focuses on the mineral systems approach to ore deposit formation, a holistic framework that considers the entire geodynamic context, from metal sources and transport pathways to depositional environments and preservation. He applies fluid inclusion analysis and a suite of petrological and geochemical techniques to investigate hydrothermal and metamorphic ore systems enriched in Ni, Co, Zn, Sb, and rare earth elements.

He conducts high- and low-temperature calorimetric experiments to generate fundamental thermodynamic data that inform predictive models of mineral stability and support exploration and processing strategies for critical raw materials. His research also examines how structural and chemical factors govern the stability of both natural and synthetic materials, with applications across geoscience and materials science. In service to the broader research community, he contributes to the development of open-access thermodynamic databases.

A committed educator, Scharrer integrates research into the classroom through his courses in economic geology and applied thermodynamics. He actively mentors undergraduate and graduate students, offering hands-on experience with state-of-the-art analytical and experimental techniques to prepare them for impactful careers in academia and industry.

Bradley Thomson

As a planetary geologist Bradley Thomson is interested in understanding the physical processes that have shaped the surfaces of the terrestrial planets, including impact, eolian, fluvial, lacustrine, and volcanic processes. Thomson has endeavored to unravel the complex geologic histories of Mars, the Moon, and Venus using geologic mapping and geologic analysis with diverse types of remotely sensed data, including radar, optical, near-IR, thermal, and surface contact data. An overarching theme of Thomson’s research is to constrain the nature and timing of physical processes in ancient planetary environments, particularly the drivers of planetary-scale climate change. Thomson has also employed terrestrial analogs to provide greater insight into planetary processes. Furthermore, Thomson has developed numerous pieces of custom-built software (particularly in MATLAB) to facilitate research.

Jeff Moersch

My formal training as a scientist began with a Bachelor’s degree in Physics (Cornell), followed by a Master’s in Geology (Arizona State University), a Master’s in Astronomy (Cornell), and a Ph.D. in Astronomy (Cornell). After grad school, I worked for two and a half years in the Exobiology Branch at NASA Ames Research Center as a Resident Research Associate of the National Research Council. In June, 2000, I moved to a research faculty position in the (then) Department of Geological Sciences at U.T. My appointment as Assistant Professor in the Department of Earth and Planetary Sciences at U.T. begins in August, 2003.

My research interests can be divided into two broad categories related to planetary geology and remote sensing: First, I am interested in using the clues provided by Martian geology to understand Mars’ present and past surface environment and its potential for having once harbored life. For example, I work with infrared spectroscopic and imaging observations of the Martian surface to understand its mineralogic composition, which in turn can tell us about things like the presence or absence of liquid water on the surface in the past. The second broad category of my research deals with the technical aspects of building new science instruments for use on planetary spacecraft missions and optimization of the science yield from instruments in new operational environments.

Much of my work involves planning, acquisition, and analysis of data by orbital and surface-based spacecraft at Mars. My involvement with NASA spacecraft missions began when I was a student, working on the Voyager 2, Galileo, and Mars Observer missions. As a professional scientist, I’ve served as a Science Team Member on the Deep Space 2/Mars Microprobe mission, the Mars Odyssey Mission, and the Mars Exploration Rover mission.

I place a large emphasis in my research on the ground-truth knowledge that can be gained from work on the Earth. This includes remote sensing and field studies of terrestrial analogs for Martian geologic features, and participation in Mars rover mission simulations on Earth, which teach us how to effectively use robots to do field geology. Laboratory spectroscopic studies and telescopic observations are other techniques I have employed over the course of my career to round out my approach.

One of the most enjoyable aspects of my work is that it tends to be very interdisciplinary, so there are ample opportunities for me to learn new skills on every project. Cutting-edge technology is part-and-parcel of the work, which suits my gadget-oriented personality well. The very best part of my job is the feeling of exploration that comes from seeing a new corner of the solar system for the first time whenever one of our missions succeeds.

Nicholas Dygert

Nick Dygert grew up in Washington State and gained an appreciation for geology climbing mountains in the Cascades and Olympics. As an undergraduate at the University of Rochester, Dygert wrote a thesis on the geochemistry of an anomalous crater on the Bolivian Altiplano. After two years in geotechnical and environmental consulting, Dygert went on to graduate school at Brown University, followed by a postdoctoral fellowship at the University of Texas at Austin, before joining the faculty at the University of Tennessee in 2017. In 2019, Dygert was named the Larry and Dawn Taylor Assistant Professor of Planetary Geosciences. Dygert uses field investigations, experiments, and numerical models to understand processes that shape the evolution of planetary interiors and crusts, and to interpret their expressions in the rock record.

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Mars & Mars Analog Research