Graduate Students

Jordan Bretzfelder

Jordan Bretzfelder is pursuing her PhD in Geology. She completed her B.S. in Physics at the University of Southern California in 2019. Prior to joining Professor Day’s GALE lab, and concurrent with her studies at USC, she spent three years researching the lunar mantle at the Johns Hopkins Applied Physics Laboratory. Her interest in Planetary Sciences began with a summer spent mapping surface features on Europa for the Center for Earth and Planetary Sciences

In 2018 Jordan received the Stephen E. Dwornik award at the 49th Lunar and Planetary Sciences Conference in Houston for an oral presentation of her Lunar mantle research. Though her previous work relied heavily on remote-sensing and spectral data, she is excited about the laboratory experiments and field work she will undertake as a member of the GALE lab. 

At USC Jordan conducted high school outreach projects and she looks forward to the opportunities to encourage and uplift other underrepresented students in STEAM while contributing to an inclusive community in planetary science.

Bretzfelder, J. M., Klima, R. L., Greenhagen, B. T., Buczkowski, D. L., Petro, N. E., & Day, M. (2020). “Identification of Potential Mantle Rocks Around the Lunar Imbrium Basin.” Geophysical Research Letters 47.22 (2020): e2020GL090334.

Bretzfelder, J. M. and M. Day, “Alien Aeolian Bedforms: a Comparative Sedimentary Analysis of the Dingo Gap Bedform and Hidden Valley Ripple Traverses, Gale Crater, Mars,” accepted to Journal of Geophysical Research: Planets.

Taylor Dorn

Taylor Dorn is a doctoral student at UCLA with wide-ranging research interests focusing on sedimentary processes on Earth and Mars. He combines field work, remote sensing, and experimental studies to answer the many unknowns in this diverse research field. Aside from research, Taylor is an officer in the UCLA Earth, Planetary, and Space Science Student Organization (EPSSSO) and involved in the ‘Letters to a Pre-Scientist’ program that allows middle school students a more accessible and personal view of science. Prior to joining Mackenzie Day’s GALE research lab at UCLA he received his Masters’ degree in Geology at the University of Louisiana at Lafayette and a Bachelors’ degree in physical geography at Texas State University. More of Taylor’s work can be found at

Dorn, T., and M. Day, “Intracrater sediment trapping and transport in Arabia Terra, Mars.” Journal of Geophysical Research: Planets 125.9 (2020): e2020JE006581.

M. Day and T. Dorn, “Wind in Jezero crater,” Geophysical Research Letters, 46, (2019), pp.3099– 3107.

Jonathan Sneed

Jonathan Sneed is a doctoral student with a diverse scientific background and an interest in geological processes throughout the solar system.  His early scientific experience was in geological oceanography and coastal sedimentation, as well as deep-time geobiology and Paleoarchean microbial studies.  After completing his Masters’ degree at Texas A&M in 2015, he began work at the Exoplanet and Solar System Habitability Group at the University of Chicago, using satellite data to characterize sedimentary and fluvial processes on the surface of ancient Mars.  Since joining GALE labs in 2018, Jonathan has continued to develop methods for the remote detection of impact events on the modern Martian surface, and is pursuing his interests in the unique characteristics and potential habitability of extraterrestrial aeolian systems.

Jacob Widmer

Jake Widmer joins the GALE lab group as a master’s student working toward a degree in Geology with an emphasis in Planetary Science surface processes. His research experience began in 2017 and has developed through several internships with the Jet Propulsion Laboratory (JPL) and the Smithsonian’s Center for Earth and Planetary Studies (CEPS). Thus far, Jake’s research has utilized remote sensing and GIS programs to investigate surface processes for Mars and Europa with an emphasis on present-day activity, aeolian environments, and seasonal processes.

Since graduating from the University of Maryland in 2019 with a B.S. in Geology, Jake has developed several projects to better understand martian seasonal frost and snowfall processes. Moving forward, he is excited to bring a seasonal perspective to the already well-rounded GALE lab group and new aeolian investigations.