August 11, 2026

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Speaker: Mercedes Jordan, Graduate Student, The University of Texas at Austin

Title: Extraction and Analysis of Near-Surface Physical Properties from Low-Frequency Lunar Radar

Abstract: The Moon’s surface has long been analyzed using various imaging and spectroscopic techniques; However, these instruments are sensitive only to the upper micrometers to millimeters of the lunar surface, limiting their ability to probe materials at depth. As a result, ground-penetrating techniques such as radar are required to investigate the physical and compositional properties of mare basalts beneath the Moon’s global regolith layer. The Lunar Radar Sounder (LRS) instrument was designed to image deep lunar subsurface structure using low-frequency radar (5MHz). By isolating and analyzing the surface echo, this same dataset can be used to probe near-surface (<75 m) physical properties that are inaccessible to optical techniques. In this work, we use LRS radar surface reflectivity to examine physical heterogeneities within the nearside lunar maria.We first describe the construction of radar surface reflectivity data products, including key filtering and processing steps. Focusing initially on a restricted region of interest, we observe a correlation between radar power and ilmenite abundance. When the region of interest is expanded to encompass the lunar maria more broadly, however, this relationship breaks down, particularly across Mare Tranquillitatis, the oldest basin in the study area.

This breakdown motivates an investigation of mare age as a controlling variable. Using a piecewise multiple linear regression, we find that radar surface reflectivity varies systematically with basalt emplacement age, indicating that physical evolution processes may play a primary role in controlling radar behavior at regional scales. We propose two porosity-based hypotheses to explain these age-dependent trends, relating variations in radar power to differences in bulk porosity structure within the upper basaltic substrate.

Finally, we discuss the limitations of our previous calibration of LRS surface reflectivity. Existing calibration relies on a single-layer model using permittivity measurements estimated by data from the Chang’e-5 lander over Oceanus Procellarum. We outline a future calibration approach using a thin-layer model that incorporates both regolith and basaltic permittivities constrained by Apollo samples and local regolith thickness estimates.

Biography: Mercedes Jordan is a graduate student in the Department of Earth and Planetary Sciences and the University of Texas Institute for Geophysics, where she is pursuing an M.S. in geology. Working with Dr. Sean Gulick and Dr. Cyril Grima, her research focuses on understanding radar surface reflectance and its utility as a tool for investigating near-surface physical properties in planetary environments.

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Speaker: John Hinkle, PhD Student, The University of Texas at Austin

Title: Sediment-hosted deep-sea microbial communities supported by diffuse hydrothermal fluid seepage

Abstract: Most research on the influence of hydrothermal fluids on life in the deep sea has focused on hydrothermal vents– rare environments that cover a small fraction of the seafloor. Conversely, diffuse hydrothermal systems, with slower, cooler fluid flow receive relatively little attention– yet they are estimated to play an influential role in global hydrothermal fluid circulation and heat flux. In this talk, I will propose that the slow, diffuse seepage of deeply sourced crustal or mantle fluids may provide a significant, so far overlooked source of energy substrates to microbial communities over large areas of deep-sea sediments on Earth, and potentially other ocean worlds. 

Biography: John Hinkle is a geomicrobiologist and third-year PhD student in Marine Science at the University of Texas at Austin, Marine Science Institute.