A5052728767- Planetary Science and Exploration
- Astro and Planetary Science
- Space Exploration and Technology
- Geology and Paleoclimatology Research
- Methane Hydrates and Related Phenomena
- Isotope Analysis in Ecology
- Atmospheric and Environmental Gas Dynamics
- Scientific Research and Discoveries
- Maritime and Coastal Archaeology
- Astrophysics and Star Formation Studies
- Space Science and Extraterrestrial Life
- Stellar, planetary, and galactic studies
- Arctic and Antarctic ice dynamics
- Paleontology and Stratigraphy of Fossils
- Spacecraft and Cryogenic Technologies
- Cryospheric studies and observations
- Spaceflight effects on biology
- Marine and environmental studies
- Hydrocarbon exploration and reservoir analysis
- Nuclear Physics and Applications
- Geological Studies and Exploration
- Geological and Geochemical Analysis
- earthquake and tectonic studies
- Meteorological Phenomena and Simulations
- Spacecraft Design and Technology
University of Oklahoma
2025
Laboratory for Atmospheric and Space Physics
2020-2024
University of Colorado Boulder
2020-2024
University of Colorado System
2020-2021
University of Arizona
2015-2019
Planetary Science Institute
2016-2019
Flagstaff Medical Center
2019
Lunar and Planetary Institute
2018
The surface of dwarf planet Ceres contains hydroxyl-rich materials. Theories predict a water ice-rich mantle, and vapor emissions have been observed, yet no (H2O) has previously identified. Visible InfraRed (VIR) mapping spectrometer onboard the Dawn spacecraft now detected absorption features within low-illumination, highly reflective zone in Oxo, 10-kilometer, geologically fresh crater, on five occasions over period 1 month. Candidate materials are H2O ice mineral hydrates. Exposed would...
Abstract Although ice in the Martian midlatitudes is typically covered by a layer of dust or regolith, it exposed some locations fresh impact craters erosional scarps. In both cases, massive excess with low lithic content. We find that scarps occur between 50° and 61° north south latitude they are concentrated near Milankovič crater northern hemisphere southeast Hellas basin southern hemisphere. These may represent particularly thick clean bodies ice. Pits created retreat...
Abstract Before acquiring highest-resolution data of Ceres, questions remained about the emplacement mechanism and source Occator crater’s bright faculae. Here we report that brine effusion emplaced faculae in a brine-limited, impact-induced hydrothermal system. Impact-derived fracturing enabled brines to reach surface. The central faculae, Cerealia Pasola Facula, postdate pit, were primarily sourced from an melt chamber, with some contribution deeper, pre-existing reservoir. Vinalia...
Abstract One important, almost ubiquitous, tool for understanding the surfaces of solid bodies throughout solar system is study impact craters. While measuring a distribution crater diameters and locations an important wide variety studies, so too crater's “depth.” Depth can inform numerous studies including strength surface modification rates in local environment. There is, however, no standard data set, definition, or technique to perform this data‐gathering task, abundance different...
Abstract The polar regions of the Moon host some most extreme low temperatures in inner solar system due to its obliquity, lack atmosphere, and topographic relief. Some these are already confirmed water ice. Proposed sources other volatiles include lunar volcanic outgassing, wind, comet impacts. Each possible would carry a potentially identifiable compositional signature beyond water. Determining dominant volatiles, therefore, requires assessing long-term thermal stability an array...
Many discoveries of active surface processes on Mars have been made due to the availability repeat high-resolution images from High Resolution Imaging Science Experiment (HiRISE) onboard Reconnaissance Orbiter. HiRISE stereo are used make digital terrain models (DTMs) and orthorectified (orthoimages). DTMs orthoimage time series crucial for advancing study such as recurring slope lineae, dune migration, gully activity, polar processes. We describe process making DTMs, series, DTM mosaics,...
Abstract The North Polar Layered Deposits (NPLD) of Mars contain a complex stratigraphy that has been suggested to retain record past eccentricity‐ and obliquity‐forced climate changes. surface accumulation rate in the current can be constrained by crater retention age. We scale NPLD diameters account for icy target strength compare age using new production function recent small impacts on previously used model Hartmann (2005). Our results indicate ice is accumulating these craters several...
Abstract Observations of a water vapor exosphere around Ceres suggest that the dwarf planet may be episodically outgassing at rate ~6 kg s −1 from unknown sources. With data Dawn mission as constraints, we use coupled thermal and diffusion model to explore three different configurations ice (global buried pore‐filling ice, global excess local exposed surface ice) could present on Ceres. We conclude table cannot alone explain production rates previously measured, but newly given right...
Abstract We present a comprehensive global catalog of the geomorphological features with clear or potential relevance to subsurface ice identified during Dawn spacecraft's primary and first extended missions at Ceres. define eight broad feature classes describe analyses supporting their genetic links ice. These include relaxed craters ; central pit large domes small mounds lobate landslides ejecta pitted materials depressions scarps fractures , grooves channels . Features in all are widely...
Abstract We provide the first solar system wide compendium of speleogenic processes and products. An examination 15 bodies revealed that six cave‐forming occur beyond Earth including volcanic (cryo magmatic), fracturing (tectonic impact melt), dissolution, sublimation, suffusion, landslides. Although no caves (i.e., confirmed entrances with associated linear passages) have been confirmed, 3,545 SAPs (subsurface access points) identified on 11 planetary potential for (and thus SAPs) was...
The UAE’s Emirates Mission to the Asteroid Belt (EMA) is scheduled launch later this decade. mission will rendezvous with water-rich asteroid (269) Justitia, and along way flyby 6 different main belt asteroids. EMA goals combine both scientific investigation on nature of asteroids determining resource potential present in asteroidal bodies. While all flybys be too fast enable precise mass estimates, Justitia include estimating its mass, gravity field internal density distribution...
Abstract We investigate the importance of viscous flow in shaping topography at north polar layered deposits (NPLD) Mars by using finite element modeling to calculate distribution stresses and velocities. Present‐day impact craters on NPLD are too small cold for relaxation have been an important mechanism controlling their current dimensions; this effect may be ignored when analyzing crater size‐frequency distributions. Scarps margins, where avalanches dust carbon dioxide frost occur,...
Abstract Water ice exists at the lunar poles, but its origin, abundance, and distribution are not well understood. One potential source of water to poles is volcanic outgassing volatiles from interior subsequent condensation erupted vapor as surface ice. We investigate whether a viable for accumulation polar construct model that accounts outgassing, atmospheric escape space, over period peak activity (4–2 Ga) map resulting abundance using current temperature data Lunar Reconnaissance...
Pteridophytes-vascular land plants that disperse by spores-are a powerful system for studying plant evolution, particularly with respect to the impact of abiotic factors on evolutionary trajectories through deep time. However, our ability use pteridophytes investigate such questions-or capitalize ecological and conservation-related applications group-has been impaired relative isolation neo- paleobotanical research communities absence large-scale biodiversity data sources. Here we present...
Abstract Telescopic observations have detected an exosphere around Ceres, composed of either water vapor or its photolytic products. Proposed mechanisms for formation include sublimation sputtering from solar energetic particles buried ice, surface optically thin seasonal polar cap. We estimate the amount produced by known exposures in Dawn spacecraft image and spectral data ice subresolution impact craters. use thermal modeling to take into account slope, orientation, and, case within...
Abstract Landslides are among the most widespread geologic features on Ceres. Using data from Dawn's Framing Camera, landslides were previously classified based upon geomorphologic characteristics into one of three archetypal categories, Type 1(T1), 2 (T2), and 3 (T3). Due to their context, variation in age, physical characteristics, Ceres are, however, intermediate morphology properties between archetypes each landslide class. Here we describe varied individual landslides, identify controls...
Abstract The ice-rich crust of dwarf planet 1 Ceres is the source a tenuous water exosphere, and behavior this putative exosphere investigated with model calculations. Outgassing molecules seasonally condense around winter pole in an optically thin layer. This seasonal cap reaches estimated mass at least , aphelion summer may even retain throughout summer. If reservoir suddenly released by solar energetic particle event, it would form denser transient exosphere. Our calculations also explore...