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Planetary Geoscience

The Department of Earth and Planetary Sciences is very active in research throughout the Solar System. Our group includes 7 professors and close to 20 graduate students conducting a variety of processes using a range of scientific techniques, including laboratory studies of meteorites and lunar samples, spectroscopic observations of asteroids and Mars, participation in spacecraft missions, and field studies of terrestrial analogs.

The Saturn System

Researchers in the UT EPS Department are investigating various processes and landforms on the surface of Titan, the largest moon of Saturn.  At ten times Earth's distance from the Sun, Titan is a frozen world whose surface is largely water ice.  But recent images from Titan reveal a surprisingly Earth-like landscape.  Fluvial features formed by flowing liquid methane/nitrogen have carved terrestrial-style river networks on Titan's surface. And the winds in Titan's thick atmosphere have produced extensive aeolian dunes covering ~20% of the satellite's surface.

Devon Burr is conducting investigations into both aeolian and fluvial processes on Titan.


The geomorphology of Mars also provides important clues to the history and evolution of Mars.  Prof Burr has studied a range of aqueous landforms, including outflow flood channelsinverted river channels, and ground ice features, in order to better understand the history of water on Mars, and how it has shaped Mars' surface. See Devon Burr's webpage for more information.

Pluto and the Kuiper Belt

Sedna OrbitFifteen years ago, textbooks described the Solar System as consisting of nine planets, the last being a small, icy oddball in a somewhat eccentric and very lonely orbit that reached ~40 AU from the Sun.  That oddball, Pluto, is no longer so odd or lonely, but it is also no longer a planet!  In the past decade-and-a-half, astronomers have discovered more than 1200 objects that orbit the Sun beyond Neptune, and more are being discovered every day.  Pluto, it turns out, is just one member of the Kuiper Belt, a belt of icy bodies analogous to the asteroid belt of rocky bodies between Mars and Jupiter.  Several of these Kuiper Belt objects (KBOs) are similar in size to Pluto, and one is even bigger than Pluto!  Some KBOs travel to much greater distances than Pluto – one, Sedna, swinging to nearly 1000 AU from the Sun. 

KBOs show some interesting groupings in their orbits that provide strong evidence that Neptune did not form where we see it now.  Rather, astronomers now think that Neptune formed closer to the Sun, and migrated to its present orbit early in Solar System history.  Researchers in the UT EPS department are investigating the surface compositions of KBOs using ground-based and space-based telescopes.  These bodies are so cold that, along with silicates (rocky material) and organic material, their surfaces consist of ices (solid phases) of CH4 (methane), CO2 (carbon dioxide), CO (carbon monoxide), N2 (molecular nitrogen), NH3 (ammonia), H2O (water).  Correlating compositions of KBOs with orbital groups will provide additional information on when and how Neptune migrated and how that migration may have affected the rest of the Solar System.

Josh Emery is involved in multiple aspects of this work.

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. 

Results of 3D and 2D textural analysis of synthetically generated martian analog sediment reported in McGlynn (2012). Original field sample is Quaternary basalt from the Cima volcanic field, Mojave Desert, CA. (A) Image of crushed sample that 2D textural data was collected from. (B) Frequency histograms for crushed sediment. Black curve represents original material sieved in 0.5 phi increments. Absence of data coarser than -2.5 phi results from our original size grouping for different purposes. Orange curve generated from an image with a resolution of 140 μm/pixel. Blue curve generated from an image with a resolution of 37 μm/pixel. Note considerable improvement in results. (C) Comparison of grain rounding between 2D and 3D data. Low-resolution (140 μm/pix) analysis overestimated rounding, whereas average for high-resolution (37 μm/pix) analysis closely resembles the 3D grain analysis. Large symbols = group averages. (D) Sphericity comparison of 3D and 2D data. 2D data regardless of resolution consistently over estimates sphericity relative to 3D measurements, but there is strong overlap.

Representative Publications

  • Fedo, C.M., McGlynn, I.O., and McSween, H.Y., Jr., 2015, Grain size and hydrodynamic sorting controls on the composition of synthetic, analog, basaltic sediments: implications for interpreting martian soils: Earth & Planetary Science Letters, v 423, p. 67-77, doi: 10.1016/j.epsl.2015.03.052
  • McGlynn, I.O., Fedo, C.M., and McSween, H.Y., Jr., 2012, Soil mineralogy at the Mars Exploration Rover landing sites: an assessment of the competing roles of physical sorting and chemical weathering: Journal of Geophysical Research – Planets, v. 117, E01006, doi:10.1029/2011JE003861
  • McGlynn, I.O., Fedo, C.M., McSween, H.Y., 2011, Origin of basaltic soils at Gusev Crater, Mars by aeolian modification of impact-generated sediment: Journal of Geophysical Research – Planets (Special Issue in MER Rovers), v. 116, E00F22 doi: 10.1029/2010JE003712
  • Lang, N.P, Fedo, C.M., and Whisner, S.C., 2011, Terrestrial analogs in the Mojave Desert of the southwestern United States for volcanic, sedimentary, and tectonic processes on other planets: Geological Society of America Special Paper 483, p. 465-482.

Mars Science Laboratory Mission

As a co-investigator on the Mars Science Laboratory mission, I am involved in both orbital mapping of Gale Crater, as well as in strategic planning, daily spacecraft operations, and the interpretation of geologic data. I work primarily with the Mast and MAHLI cameras, which were built by Malin Space Science Systems. After the Curiosity rover landed on 6 August 2012, we spent several months testing and calibrating analytical equipment. We then moved to a region of layered strata, called Yellowknife Bay, where we analyzed the depositional and diagenetic environments of ancient lacustrine deposits. At present, we are heading toward Mount Sharp, where we will begin to investigate the habitability potential of depositional environments recorded by a thick package of layered strata. I give many outreach presentations on the Curiosity mission, including a keynote at the 2012 Council for the Advancement of Science Writing (CASW) annual convention.


Jeff Moersch studies the composition of the Martian surface through geochemical and spectroscopic investigations. These investigations provide information on the evolutionary history of Mars and its potential for having hosted life. He also conducts extensive field work in terrestrial field sites that are good analogs for Mars, such as the Atacama Desert, Iceland, and the Arctic. Moersch serves on the science teams for the Mars Exploration Rover mission (Opportunity) and the Mars Science Laboratory mission (Curiosity), which are currently searching for evidence of past habitable environments on the Martian surface. He also is a member of the science team for the Mars Odyssey spacecraft, which is providing data for mapping the composition of the Martian surface from orbit. Finally, Moersch is actively involved in instrument development work for future planetary exploration missions.

Anna Szynkiewicz has been working on application of chemical and sulfur-oxygen isotope tracers to determine and quantify various factors controlling sulfur cycling, water salinity and the flows of surface water/groundwater in semi-arid regions of American Southwest. The results have allowed for presenting the conceptual model for the origin of water salinity in semi-arid environments via repeating cycles of salt efflorescence (sulfates, chlorides) dissolution and reprecipitation in shallow surface environments. As shown in recent manuscript published in Earth and Planetary Science Letters, this model is useful for understanding the sources and formation timescales of hydrated sulfates in Valles Marineris on Mars.

Szynkiewicz has been also studying fluxes of aqueous sulfate from modern emission of hydrogen sulfide and chemical weathering in a volcanic system of Valles Caldera, New Mexico. This study is funded by NASA Mars Fundamental Research grant and is a first attempt to describe and quantify total sulfur budget in the volcanic hydrological system, including assessing preservation of sulfur-bearing minerals in crater lake sediments.

In early investigation, Szynkiewicz's planetary research was to reconstruct paleo-hydrological eolian conditions in the saline lakes and gypsum dune fields of the Rio Grande rift (e.g., White Sands, Cuatro Ciénegas) and compare them to sulfate-mineral deposition in equatorial and polar regions on Mars. Using sulfur isotope geochemistry, she was able to characterize the various roles of shallow and deep water flows in deposition of sulfate minerals, preservation of sulfur isotope bio-signatures related to microbial sulfate reduction, indicate the role of cold climate conditions in enhancing sulfide weathering, and define major factors controlling eolian sulfate-mineral cycle. Three peer-reviewed publication in Geochimica et Cosmochimica Acta, Geomorphology, and Journal of Geophysical Research have been published so far, which discuss major findings of this study and their relevance to Mars.

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