Surface processes on Mars, icy airless worlds and in the laboratory
Through a combination of analog experiments in planetary simulation chambers and geomorphological analysis of remote-sensing imagery, my work explores:
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Linear Gullies on Mars
Linear gullies are strange, often sinuous channels terminating in pits that are detected on Martian dunes in the Southern mid-latitudes. They are proposed to form by sliding dry ice blocks in spring. We analyzed pit volume change at several sites over subsequent Mars years and conducted analog experiments to test whether CO2 sublimation can form pit morphologies under simulated Mars conditions.
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Spiders on Mars
Spiders are beautiful dendritic or `branched’ negative topography features that form within the Martian South Polar Layered Deposits. In spring, dark fans and spots emanate from their centers and troughs. They are proposed to form via the Kieffer Model, where sunlight penetrates translucent slab ice in Spring and heats the regolith beneath, resulting in a buildup of gas beneath the slab, consequent rupture of the overlying ice and scouring of the Martian surface by a escaping CO2 gas. I lead many research efforts to test this hypothesis in the lab and via HiRISE and CTX image analysis, to investigate the environmental conditions under which spiders form.
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Cryovolcanic Features on Europa
There are many interesting surface expressions on Europa that may be indicative of subsurface brine extrusion. We conducted a recent study to investigate the formation of Manannán crater’s `spider’ feature, using geomorphological mapping, low-temperature laboratory experiments and modeling to propose transient near-surface brine activity and melt of impact slurry as a new formation hypothesis.
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Lake Stars on Earth
Lake stars are beautiful dendritic ice features that are found on Earth’s frozen lakes in winter. They form when snow falls on a frozen lake and the weight of the snow causes holes to form in the ice. Relatively warm water wells through the snow/slush and an instability forms in the flow of water melting ice grains of different sizes, causing a dendritic or branched melt pattern. Eventually the slush freezes again, preserving this pattern as a `lake star. In our Europa study, we use the formation of Earth’s lake stars as a basis for our proposed formation hypothesis for Manannán crater’s spider feature. Part of this work involved field tests in Breckenridge, Colorado, where I analyzed several clusters of lake stars in order to understand the conditions under which they form.
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Transient Brine Flow on Ceres & Vesta
I collaborated with researchers at JPL and SWRI to perform experiments in JPL’s DUSTIE thermal-vacuum chamber to test the transient brine flow hypothesis for gullies on Ceres and Vesta. This study showed that brines can exist as liquid under a thin lid for up to an hour under simulated post-impact pressure regimes predicted for icy airless worlds, and for ~5 minutes when exposed to the surface and stirred.
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Constraining Potential Source Locations of Martian Meteorites
Martian meteorites represent the only samples of Mars available for study in terrestrial laboratories and can provide a detailed understanding of the geochemistry of the martian crust. One of the major outstanding problems regarding martian meteorites is locating the exact source regions on Mars. To help narrow down likely source craters, we developed a global catalog of impact craters greater than 3 km diameter with thermally distinct radial patterns (“rays”), which could represent recent impact events. Using daytime and nighttime thermal infrared image data we identified 118 craters with thermally distinct radial patterns between ±60° latitude, of which 89 had not appeared in previous catalogs. Our preliminary analysis demonstrates the potential future use of this catalog in finding the source location of martian meteorites in regions of sufficient thermal contrast.
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Potentially Periglacial Terrain on Mars
Using HiRISE images, I carried out mapping of High Centered Polygons (HCPs) and Low Centered Polygons (LCPs) in Utopia Planitia and showed that the ratio of LCPs to HCPs increases with poleward latitude, supporting a possible ice-wedging origin.
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Planetary Simulant Development
I have experience developing and analyzing fine icy/salty granular ice simulant for applications relevant to icy planetary surface integrity and sample acquisition testing, Enceladus plume sample collection and research on Europa’s geomorphology
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Planetary Simulation Chamber Design and Development
I enjoy designing and implementing modifications to vacuum chambers that can simulate planetary environments. At JPL, I led upgrades to the Dirty Under-vacuum Simulation Testbed for Icy Environments (DUSTIE), originally used to test a prototype for the Phoenix Mars lander RASP tool - and got to name the chamber! I also helped to generate a science customer-base and was the point of contact for the chamber during my postdoc. At UCF, I am now building 2 chambers; DUSTIE’s `sister’ chamber, SANDIE and a Europa chamber, SLUSHIE.