Research
My research interests include developing sophisticated numerical forward models and performing probabilistic (e.g., Bayesian) inversions aimed at understanding the tidal dynamics, evolution, tectonics, volcanism, and habitability of planetary bodies. You can find more details on my research projects below.
(Coming soon)
Moon
The Solar System's Largest Volcano?
Nearside-Farside Differences
The moon's nearside is covered by vast plains, called mare, formed from molten rock that cooled and solidified billions of years ago. The Moon's farside has much more rugged terrain, with few plains. In addition, the lunar nearside has a much thinner crust, an elevated concentration of radioactive Thorium and Titanium, and large rifts.
It has been hypothesized that intense volcanism on the nearside surface is influenced by deeper processes (for example, temperature anomalies or
magma chambers in the mantle).
Uncovering Mantle Structure
We re-analyze data from the GRAIL (Gravity Recovery and Interior Laboratory) mission to develop a gravity map for the Moon with a horizontal resolution of about 6 km. We additionally compute parameters called tidal Love numbers, which depend on the Moon's time-varying gravitational response to tidal interactions with the Earth.
We measure anomalous degree-3 Love numbers, which indicates that the nearside lunar mantle is flexing more than the farside lunar mantle. This difference in the ability of either hemisphere to deform can be explained by the presence of an internal difference in temperature of about 100-200 C between either hemisphere (with the nearside being warmer).
A Hemisphere-Scale Volcano?
A warmer nearside could indicate the presence of deep-seated partial melt (that is, magma chambers) in the lunar mantle (between 800 - 1200 km depth). This melt may be a remnant of geologic processes which formed the nearside maria about 4 billion years ago, and may influence the distribution of small-magnitude 'moonquakes' observed in the present-day interior.
Enceladus
Saturn's Geologically Active Satellite
Over the course of its elliptical orbit, the moon Enceladus is squeezed unevenly by Saturn's gravitational pull and deforms from a spherical shape into a football shape and back again. This cyclic stress causes so-called "tidal heating" in Enceladus and dissipates enough energy to maintain what is believed to be a global ocean underneath the moon's icy crust.
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Geologic Activity at Enceladus
At Enceladus's south pole, a large number of jets spray icy particles out from a set of jagged, 150-kilometer-long faults—known as the tiger-stripe faults. This ejected material coalesces above the moon's surface to form a plume. The plume above Enceladus’ south pole varies in intensity, waxing and waning in strength, with two notable peaks in emission during the moon’s 33-hour orbit.
To better understand mechanisms controlling jet activity, I developed a sophisticated numerical (finite-element) model to simulate strike-slip motion along Enceladus’ faults. These models consider the role of friction, which causes the amount of slip on the faults to be sensitive to both compressional and shearing stresses. The numerical model was able to simulate slip along Enceladus’s faults in a manner which matched the variations in plume brightness as well as spatial variations in surface temperature, suggesting that the jets are controlled by strike-slip motion over Enceladus’ orbit.
To explain the apparent correlation between jet activity and strike-slip motion, we theorize that variations in the flux of plume material is due to “pull-aparts” in the faults—bent sections that open under broad strike-slip motion.
Bottom: image adapted from our 2024 Research Article
Read more in our 2024 paper in Nature Geosicence
Characterizing Enceladus's Lumpy Crust
Enceladus's crust varies in thickness from ~50 km near its equator to ~10 km at the poles. These variations in thickness induce a variation in the response of the crust to tidal forces, which can be potentially be measured using advanced radar techniques (e.g., inteferometric radar or InSAR).
I developed a methodology to recover lateral variations in crustal thickness at Enceladus using potential measurements of elastic strain over the surface of the moon. This approach involves initially recovering crustal thickness based on the expectation that local thickness is inversely proportional to tidal strain (i.e., Hooke’s law), then iteratively updating thickness values to minimize differences between a measured crustal strain field and that produced by numerical models. The newly developed methodology enables determinations of thickness with an accuracy of ~2 km across the crust.
I also use numerical models to understand whether inferences of mean crustal thickness derived from Enceladus' response to tidal forcing are sensitive to the presence of 3D structure (e.g., faults, thickness variations). Results from numerical models demonstrate that tiger stripes produce highly localized deformation near their tips and have minimal impact on the moon’s predicted long-wavelength tidal response. By contrast, regional thinning of the crust near the South Pole creates a long-wavelength displacement pattern that can bias estimates of mean crustal thickness by up to ~20%.
Read more in our 2023 paper in JGR: Planets our 2024
paper in Geophysical Research Letters, and our 2024 paper in
JGR: Planets
or the LPSC/AGU presentations below
Bottom: image of Enceladus enmeshed in Saturn's E-Ring
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