B.Sc., State University of New York at Albany, 1996
M.Sc., Earth and Space Sciences, Stony Brook University, 2001
Ph.D., Geosciences, Stony Brook University, 2006
Hydrogeologist, Leggette Brashears & Graham, Inc., 1996-98
Caltech Postdoctoral Scholar at Jet Propulsion Lab, 2006-2007
Research Scientist, NASA-Jet Propulsion Lab, 2007-2013
Research Scientist, Stony Brook University, 2013-2014
Current Research Projects:
1. In-situ Exploration of the Surface of Mars: Observations by a veritable fleet of orbiters sent to Mars have been used to develop and refine hypotheses about how the Red Planet evolved from a more Earth-like state in its early history, to the cold desert world we observe today. Testing these hypotheses requires close-up examination of the sedimentary rock record, which contains the clues needed to understand climate evolution on Mars. I am the Deputy Principal Investigator for the Planetary Instrument for X-ray Lithochemistry (PIXL), which was selected by NASA to fly on the upcoming Mars 2020 Rover mission (M2020). This project is based at the NASA-Jet Propulsion Laboratory. I am working with PIXL Principal Investigator Dr. Abigail Allwood to develop and test PIXL prototypes and the PIXL flight instrument for operation after landing on Mars, currently scheduled for the year 2021. My laboratory is outfitted with a “breadboard” version of the PIXL instrument, which is available for students to use for chemical element mapping to support their research, and to train for upcoming opportunities (beginning in 2020) to get involved in PIXL instrument operations on M2020.
2. Analogue Field Studies : On Earth, the geochemical and mineralogical composition of clastic sediments are dominated by inputs from the petrologically-evolved granodioritic upper continental crust and recycled sedimentary materials derived from this crust. A comprehensive understanding exists of the processes that influence the composition of sediments derived from felsic materials as they evolve from their source terrains, along transport pathways, to their sites of accumulation. In contrast, far fewer examples of sub-aerially exposed basaltic crust with extensively developed source-to sink sedimentary drainages exist on Earth. Outside of subaerial weathering of basalts, the processes and products of basaltic sedimentation have gone largely unstudied in the terrestrial geological record. As a result, we lack a suitable reference frame in which to place the Martian sedimentary rock record, which is dominated by first-cycle basaltic sources. We are working to build this reference frame through a field research program based in fluvial drainage systems in basaltic terrains, including Idaho, Iceland, and Hawaii.
In addition, my group has begun exploring the chemical record of Paleoproterozoic seawater preserved in iron formation as an analogue to Fe-rich water bodies on the early surface of Mars, in collaboration with Professors Troy Rasbury and Greg Henkes. Iron formations are characterized by high Fe-abundances and a variety of Fe-minerals formed by interactions between dissolved Fe 2+, atmospheric oxidants, and carbon. Terrestrial iron formations are also host to some of Earth’s most ancient records of life, including molecular biomarkers and microfossils. Accordingly, terrestrial iron formations, like the Paleoproterozoic Gunflint Formation, can provide valuable insight into Fe-redox and precipitation processes on the ancient surface of Mars. Critically, the Gunflint contains the Fe-carbonate mineral siderite, which can be exploited to gain insight into two critical components of the habitability of water bodies on early Mars: pH and temperature. Our goal is to determine whether the boron and carbonate clumped isotope compositions of siderite from the Gunflint iron formation can be used for the determination of seawater pH and temperature, respectively.
3. The reactivity and toxicity of planetary regolith: Silicate minerals that have been mechanically pulverized by impact processes on planetary bodies have surfaces that are populated by broken, highly reactive, cation-oxygen bonds. These broken bonds generate reactive oxygen species (e.g., OH ˙, O 2 ˙ - , and H 2O 2) and O 2 when contacted by liquid water or water vapor. The reactivity of quartz has been well studied by medical researchers and toxicologists, as it bears directly on the causes behind silicosis. However, the reactivity of mineral phases on basaltic planetary bodies such as the Moon is little studied, and requires further exploration to assess the potential toxicity of planetary regolith to astronauts. We are exploring this theme through the recently selected Stony Brook node of the Solar System Virtual Exploration and Research Institute (SSERVI), led by Professor Timothy Glotch.
4. Experimental Aqueous Geochemistry: Our group uses an experimental approach in which Martian fluid conditions are constrained based on whether experimentally precipitated minerals (or mineral assemblages) provide a match to mineralogical and geochemical observations from the surface of Mars. Starting in 2018, we will be conducting mineral precipitation experiments at room temperature under anoxic conditions in a CO 2-purged anaerobic chamber order to approximate atmospheric conditions on the early Martian surface. Room temperature experimentation, while an admittedly imperfect match to the full potential range of surface environmental temperatures, has many benefits: (i) experimental simplicity, (ii) reasonably rapid rates of reaction, (iii) enables comparisons to thermodynamic databases of aqueous speciation and mineral saturation, which typically have maximum information content for STP conditions. Within this broad set of constraints, we will be pursuing three main themes of investigation:
Explore the conditions and rates of Fe-oxidation by ultraviolet light under anoxic conditions.
Investigate the behavior of select trace metals in Martian surface water bodies in the presence of experimentally precipitated Fe-oxide minerals.
Investigate the uptake of boron in Fe-carbonate.