When
9 a.m. – 5 p.m., Today
Where
Kuiper 308
PTYS graduate students present their research - Science talks and poster session.
Talks | Title | Abstract | |
---|---|---|---|
9:00-9:05am | Welcome and Introduction | ||
9:05-9:25am | Gabe Gowman | Lunar Mantle Beneath the South Pole-Aitken Basin Rim: Evidence from Gravity and Mineralogy | One of the major goals of the upcoming exploration of the Moon by the Artemis missions is sampling the ejecta of the ancient South Pole-Aitken (SPA) impact basin, including mantle- and magma ocean-derived materials contained therein. However, despite model predictions of large volumes of sub-crustal material in the ejecta, clear observational evidence of the nature and distribution of the ejecta in surface observations remains elusive. Here we show the presence of a ~400-km-wide band of large-amplitude, small-scale gravity anomalies forming an annulus inside the basin’s topographic rim, interpreted as mantle-bearing ejecta from the basin-forming impact in concentrations up to ~50%. Three craters excavate into the sources of these anomalies, revealing a heterogeneous mantle at the time of the SPA impact. Thus, gravity and mineralogical data reveal the presence, distribution, and composition of the lunar mantle excavated by SPA that will be available for collection by astronauts in the next decade. |
9:30-9:50am | Melissa Kontogiannis | X-Ray Computed Tomography of Samples from Asteroid Bennu: Textural Analysis and Sulfide Segmentation for Lithology Characterization | On September 24, 2023, samples of asteroid (101955) Bennu were delivered to Earth by NASA’s OSIRIS-REx mission. Among the mission’s goals are characterization of the mineralogy and composition of the sample, understanding hydrothermal alteration processes that occurred on Bennu’s parent body, and comparing sample lithologies to remote observations of Bennu. In pursuit of these objectives, we use X-ray computed tomography (XCT), a non-destructive 3D imaging technique, to perform a comprehensive textural characterization of millimeter-scale Bennu particles. Initial analyses identified three distinct particle morphologies within the sample, which are visually evident in larger stones; we use XCT textural analysis to classify smaller particles and compare characteristics of each morphology. Given the apparent relationship between these three morphologies and boulder populations observed on Bennu, this analysis is particularly relevant in comparing laboratory characterization with remote sensing data. Bennu’s distinct boulder populations are expected to have differing physical properties, including density, so we investigate whether these differences are evident on smaller scales. This study also focuses on the abundance, orientation, and distribution of sulfide minerals determined from XCT data, as these characteristics are a useful basis for comparing candidate lithologies. We are also using this data to inform the selection of sulfide grains for compositional analysis, as the compositions and textures of these minerals help to constrain formation conditions and subsequent alteration. |
9:55-10:15am | Nathalia Vega Santiago | Magnesium Sodium Rich Phases in Astromaterials | The OSIRIS-REx mission successfully returned pristine material from asteroid Bennu, revealing the presence of distinctive Mg, Na-rich phosphate phases. These phosphates are crucial for understanding prebiotic chemistry due to their bioessential phosphorus content, which plays a key role in molecules like DNA and ATP. The study explores their formation through low-temperature aqueous alteration, solar nebula condensation, or impact-induced metamorphism, shedding light on dynamic processes in Bennu's history. Elemental analysis of these phases using the Focus Ion Beam Scanning Electron Microsocope sheds light into the possible origins of phosphate accumulation. This discovery provides insights into the chemical pathways that may have facilitated life's emergence through the deliverance of organic compounds. |
10:15-10:25am | Break | ||
10:25-10:45am | Jingyu Wang | Development of Photochemical and Radiative Transfer Models for the Atmosphere of Venus and Exo-Venuses | Exoplanet Venus analogs (exo-Venuses) are expected to be characterized in the near-term by the James Webb Space Telescope (JWST). Such observations offer the opportunity to test rocky exoplanet atmospheric climate and photochemistry models in novel regimes, vital for refining them and building the robust modeling infrastructure that will be required to interpret anticipated observations from upcoming facilities like the Habitable Worlds Observatory (HWO) in search of signs of life. However, many uncertainties remain in current understanding of Venusian atmosphere, which is the cornerstone of studying exo-Venuses. Therefore, we are constructing new Venus photochemical and radiative transfer models based on existing models for temperate terrestrial planets. We are adapting the MIT Exoplanet Atmospheric Chemistry model (MEAC) by updating and extending the chemical network to include Cl species, incorporating particle scattering and UV absorber by parameterized absorption, and employing new data from laboratory experiments (ExCITE-PM collaboration). We will calculate atmospheric structure from the Linearized Flux Evolution radiative transfer model (LiFE) and couple the models to self-consistently compute photochemistry and climate. In addition to interpreting anticipated observations of exo-Venuses and testing atmospheric models in general, our models can also be used to investigate anomalies in Venusian atmosphere, which signal unknown chemistry not yet incorporated into atmospheric models. We plan to open-source our models, once developed and validated, to enable community validation and extension. |
10:50-11:10am | Kayla Smith | The Influence of Clouds and D-Burning on Brown Dwarf Habitable Zones | We compute a new set of equilibrium temperatures for planets orbiting brown dwarfs. Unlike previous work that used simple analytic scaling relationships for the brown dwarf luminosity vs. time, we use the outputs of sophisticated brown dwarf evolution models that account for the effects of deuterium burning, cloud formation and dissipation, and the most recent atmospheric opacities. Cloudy brown dwarfs cool more slowly than non-cloudy brown dwarfs, allowing planets orbiting them to remain in the habitable zone for millions of years longer than previous estimates. Similarly, we find that during the deuterium-burning phase of brown dwarfs, planets at the same orbital radius but orbiting brown dwarfs of different masses can remain in the habitable zone for the same duration, creating deuterium “sweet spots” for habitability. For example, at 0.01 AU a planet orbiting both a 12 MJ and a 20 MJ brown dwarf stays in the habitable zone for ~170-180 Myr because of the greater fractional impact of deuterium burning on the cooling of the lower mass brown dwarf. The size of the effect decreases with decreasing orbital radius, causing higher orbital radii to have a more pronounced deuterium burning effect. These results are not captured by the analytic approximations to the cooling used in most previous work on substellar habitable zones. We will report on these and other findings from the application of modern evolution models to the problem of habitability of planets orbiting substellar objects. |
11:15-11:35am | Rahul Arora | Exploring the Detectability of Magmatic Outgassing on Exoplanets | The James Webb Space Telescope (JWST) has provided the potential to explore the impact of magmatic outgassing on the atmospheres of rocky exoplanets. Current models have begun to simulate strength and composition of magmatic outgassing under varying planetary conditions. This provides us an opportunity to understand the observational diagnostics and target selection of potential outgassing exoplanets. We address this by coupling a robust outgassing model with photochemical and radiative transfer models and identifying three scenarios for detection of magmatic outgassing. First, planets with orders higher outgassing compared to Earth will emit and supply high amounts of H2 to the atmosphere. This will lead to low mean molecular weight (𝜇) and a thicker atmosphere, increasing the atmospheric signal strength. For example, observations of L 98-59 d with JWST suggest evidence of a low-μ atmosphere (~10 amu) and volcanic gases such as H₂S and SO₂. Second, high outgassing rate may lead to increasing concentrations of H₂S and SO₂ which serves as the diagnostics of magmatic outgassing. Third, high concentrations of H₂S and SO₂ can lead to formation of sulfur based aerosols (S₈ or H₂SO₄). With high enough concentration these can imprint unique spectral features on the planetary spectrum. We evaluate these scenarios using outgassing and photochemical models to constrain the detectability of magmatically outgassed species under energy and diffusion-limited escape. By identifying exoplanets with the highest likelihood of detectable volcanic activity, this study provides a framework for prioritizing JWST targets to advance our understanding of planetary evolution and surface processes beyond the Solar System. |
11:40am-12:00pm | Devin Hoover | Titan's Variable Atmosphere from Cassini/UVIS Observations | The distributions of N2, CH4, and temperature in Titan’s upper atmosphere are highly variable for poorly understood reasons. Cassini Ultraviolet Imaging Spectrograph (UVIS) scans of Titan’s airglow, which provide a global view of the atmosphere, can help to uncover the origin of density and temperature variations in Titan’s thermosphere. Based on our prior conclusion that solar-driven processes remained the dominant energy source for Titan’s thermosphere throughout the Cassini mission, we designed an algorithm for retrieving N2, CH4, and H densities from Titan’s far ultraviolet (FUV) dayglow. Our retrieval considers two N fragment lines (1200Å and 1493Å), produced by photodissociative excitation of N2, and the Lyman-ɑ line (1216Å), produced by H resonant scattering. Our retrieval is the first to fully include the Lyman-ɑ line from Titan’s dayglow and therefore to provide constraints on the H population of the thermosphere. These lines are sufficient for constraining the density and temperature profiles. To characterize temperature and vertical mixing variations, we constructed a Titan atmospheric structure emulator. We use a parametrized pressure-temperature (P-T) profile in the mesosphere and thermosphere, and in the lower atmosphere, we interpolate temperatures from the SVRS database, based on Cassini CIRS observations and modeling, to the time and location of our observations. Utilizing emcee, we infer atmospheric structure parameters, including the exobase temperature, mesopause temperature, and exobase Kzz value, from the retrieved density profiles. We present results at different latitudes for 16 distinct UVIS scans. According to our preliminary results, the variability in Titan’s atmosphere is driven by solar activity and intrinsic atmospheric variability (e.g. circulation and waves). |
12:00-1:00pm | Lunch (on your own) | ||
1:00-1:20pm | Ruby Fulford | Modeling Degradation of Ancient Martian Landforms to Interpret the Pre-Noachian and Early Noachian Geologic Records | The geologic record of Mars's pre-Noachian era, which spans the formation of the crustal dichotomy at ~4.5 Ga to the Hellas giant impact ~4.1-3.8 Ga, has been largely destroyed by imapcts and erosion. The early Noachian record is only somewhat better preserved. It is therefore unclear how pre-Noachian geologic activity compares to the fluvial pulses of the late Noachian epoch or the abundant volcanism and tectonism of the Hesperian epoch. To better understand pre-Noachian and early Noachian Mars, we need to know what remnants of features formed in these epochs might look like today. To approach this question, we model the effects of Martian impact cratering and erosion on early and pre-Noachian volcanic and tectonic landforms. We then search the Martian surface for features resembling model results and use these findings to constrain the nature of pre-Noachian and early Noachian evolution. Preliminary model results suggest partial preservation of the early and pre-Noachian tectonic and volcanic records. An initial search of Mars's southern highlands found candiates for early Noachian compressional tectonic features scattered throughout the highlands and candidates for early Noachain extensional tectonics concentrated around the Hellas impact basin. We also find several candidate pre-Naochian volcanic features. Abundant global pre-Noachian volcanism is consistent with predictions that ancient volcanism was coupled with high heat flow following planet formation. |
1:25-1:45pm | Chaucer Langbert | From Stability to Chaos: Feedback-Driven Climate Trajectories of Earth-like Exoplanets | Understanding the stability and diversity of planetary climates is critical for assessing the habitability of rocky planets in the habitable zones of G-type stars. Using a zero-dimensional energy balance model incorporating coupled feedback mechanisms, we explore the dynamics of planetary climate systems, focusing on the interplay between temperature, atmospheric pCO2, and additional feedbacks. Our analysis reveals a rich spectrum of behaviors, including stable fixed points, periodic and quasi-periodic orbits, and chaotic trajectories. By simulating 1,000 randomized configurations of feedback strength, stellar flux, and volcanic outgassing rates, we identify key feedback configurations driving climate stability and the conditions under which systems converge to or diverge from attractors. This work highlights irreversible climate states and the influence of feedback amplitudes and timescales, providing insights relevant to the Gaia hypothesis, comparative planetology, and target selection for the Habitable Worlds Observatory. |
2:00-3:20pm | Poster Session | ||
3:25-3:45pm | Anna Taylor | Exoplanet Runaways: Probing Atmospheric Escape with Hydrogen and Helium Signatures | Understanding the atmospheric escape from Hot Jupiters/Neptunes is crucial for gaining insights into exoplanet evolution, demographics, and star-planet interactions. Recent observations of exoplanets undergoing mass loss show excited states of hydrogen and helium, which can constrain escape rates, thermal structure, and level populations in non-local thermodynamic equilibrium (NLTE). In particular, absorption by He I at 1083 nm and the H I Balmer lines have been detected on many exoplanets but have proven challenging to interpret. We demonstrate that even the archetype hot-Jupiter HD209458b likely presents a challenge in reconciling observations and upper limits of He I and H I Balmer transit depths that appear low relative to high FUV/NUV transit depths. We present a coupled full-atmosphere model constrained by observations from HST, JWST, and ground-based telescopes. Our results reveal that accounting for the lower/middle atmosphere leads to higher He I and H I Balmer transit depths, making it more challenging to match observations at different wavelengths. We incorporate updated excitation/de-excitation rates and high-resolution cross-sections for metastable helium, which impact the He I transit depth but do not fully resolve the problems in explaining observations. We achieve a simultaneous fit to the He I and H I Balmer transit depths by adopting a low heating efficiency that leads to a relatively low mass loss rate and diffusive separation of helium. Finally, we explore variations in stellar activity that significantly influence the He I and H I Balmer line transit depths, emphasizing the importance of near-simultaneous observations across multiple wavelengths at different times. |
3:50-4:10pm | Tyler Reese | Test Particle Computational Methods for Predicting Termination Shock Particle Energetics | Multiple research missions are generating new measurements of the cosmic ray (CR) and solar energetic particle (SEP) spectra at the edge of the heliosphere, specifically at the termination shock. Knowledge of energetic particle spectra is important to designing future deep-space missions and future human space-travel. The highest energies are attributable to mechanism known as Fermi acceleration, the wave-particle interaction at turbulent shock boundaries. This presentation will review test particle methods for evaluating shock acceleration of ions. |
4:15-4:35pm | Melissa Kontogiannis | Environmental Implications of Copper Sulfide Mineralogy in Bennu Lithologies | On September 24, 2023, 121.6 grams of material from asteroid (101955) Bennu was delivered to Earth by NASA’s OSIRIS-REx mission. Among the mission’s goals are characterization of the mineralogy and composition of the sample to understand formation and alteration processes that occurred on Bennu’s parent body, specifically hydrothermal alteration. Sulfide minerals have been identified as a ubiquitous phase in the samples returned from Bennu and are invaluable in addressing these objectives, as the compositions and textures of sulfides can provide insight into formation conditions and subsequent alteration. Initial analyses of Bennu samples have also identified three distinct particle types within the sample — hummocky, angular, and mottled. Studying the sulfide populations in these different particle types will be useful to compare their mineralogy and evaluate the extent of aqueous alteration experienced by each. Additionally, the analysis of a sulfide region identified with a composition similar to CuFe4S5, a phase that has been seen infrequently in terrestrial ores but not yet extensively analyzed could provide new insight into Cu-sulfide mineralogy and help to refine the existing Cu-Fe-S phase diagram. Overall, this study not only advances our understanding of Bennu’s geologic history and the processes that occurred on its parent body, but also contextualizes these recently returned samples within prior research on Cu-sulfide mineralogy in extraterrestrial materials and advances our knowledge of Cu-sulfide mineralogy and the geologic origin of such materials. |
4:40-5:00pm | Closing and GSC final comments | ||
Poster Presentations | Title | Abstract | |
Carson Fuls | NEOFixer: Targeting Broker for NEO Follow-Up Observations | NEOfixer is a publicly available targeting broker designed to enhance the Near-Earth Object (NEO) catalog by prioritizing follow-up observations based on planetary defense concerns. It evaluates NEOs using factors like size, Minimum Orbit Intersection Distance (MOID), observation cost, sky-plane uncertainty, and urgency, with additional confidence metrics for newly discovered objects. Using Project Pluto's Find_Orb software, NEOfixer generates ephemerides and calculates tailored follow-up priorities for observatories, synthesizing near real-time data to refine recommendations. Tests with the I52 telescope show NEOfixer's effectiveness in improving observation quality by reducing orbital uncertainties. | |
Kiki Gonglewski | Updated Occurrence Rates of Sub-Neptunes and Sub-Saturns from K2 | The surge in exoplanet discoveries over the past two decades has been transformative for exoplanet demographics, although variations in biases, limitations, and planet properties across surveys have traditionally constrained demographics studies to individual datasets. However, recent approaches that improve completeness metrics have provided us with the opportunity to combine complementary datasets for more robust occurrence rates over a broader range of star and planet populations. The K2 mission, a follow-up to Kepler, uniquely contributes to this effort by observing a larger stellar sample with much greater coverage of M-dwarfs. We calculate intrinsic occurrence rates for sub-Neptunes and sub-Saturns in the K2 sample using updated stellar parameters from Gaia, comparing them with prior studies (Zink et al. 2023). These results are the first step for integrating K2 data into broader demographics efforts alongside data from Kepler, the California Legacy Survey, SHINE, and MOA-II, providing unique coverage of close-in planets around low-mass stars in support of future studies and observations. | |
Joanna Hardesty | Conduit Flow Model for Cryomagma on Enceladus | Icy bodies in the Solar System exhibit a wide range of landforms, many of which are attributed to the transport of water or cryogenic fluids from an internal reservoir to the surface via cryovolcanism. Cryovolcanism can offer a window into the otherwise inaccessible liquid ocean below the icy shells of ocean worlds. Despite their significance, much remains unknown about the mechanics of cryovolcanic eruptions and the surface features that they form. One fundamental question is how negatively buoyant liquids, such as water and brines, can erupt through less dense ice. To address this, we focus on the dynamics of cryomagma ascent within volcanic conduits. By employing the numerical model CONFORT15, we simulate the flow properties of cryomagma during a steady-state eruption, with specific application to the icy moon Enceladus. CONFORT15 solves mass, momentum, and energy conservation equations in a 1D vertical conduit. To adapt this model for cryovolcanism, we modify several components of the code originally designed for terrestrial silicate volcanism. Our goal is to predict ascent rates, eruption velocities, and conduit behaviors that govern eruption style and emplacement mechanisms, offering insights into the fundamental processes behind cryovolcanism. | |
Euibin Kim | Martian Climate Constraints From Ice Flow Dynamics | Martian mid-latitude regions exhibit evidence of extensive glacial activity during the late Amazonian period, as demonstrated by diverse debris-covered ice landforms such as lobate debris aprons (LDAs), lineated valley fill (LVF), concentric crater fill (CCF), and Glacier-Like Forms (GLFs). These features highlight significant ice accumulation and flow, revealing the planet’s climate history and volatile exchange over the past billion years. This study uses a numerical non-Newtonian ice flow model to investigate the formation conditions of these glacial features, focusing on GLFs and LDAs. By incorporating high-resolution digital elevation models and simulating glacial dynamics under varying physical parameters, the research aims to reconstruct the environmental conditions shaping these landforms. Preliminary results validate the model and suggest future refinements, including non-uniform accumulation rates and advanced modeling techniques, to enhance understanding of Martian glacial processes and climate evolution. | |
Thea McKenna | Thermal Evolution of KREEP in the Lunar Procellarum KREEP Terrane | KREEP, or Potassium, Rare Earth Elements, and Phosphorus, is a material that has played an important role in lunar thermal evolution and is mainly concentrated on the lunar nearside in an area called the Procellarum KREEP Terrane (PKT). This material has high concentrations of heat producing elements. It is widely believed that there is a subsurface layer of KREEP that was partially excavated by the Imbrium impact ~3.85 billion years ago. However, since this layer is likely below the crust, we have few constraints on the possible depths and thicknesses of this layer. In order to explore this question, we use a one dimensional finite difference model to calculate heat diffusion over the lifetime of the Solar System given internal heating via radiogenic element decay. We use this to model various possible thicknesses and depths of a subsurface KREEP layer in order to constrain possible lithosphere uplift due to subsurface heating. Modeling is paired with tectonic observations of the PKT to attempt to validate these models, as signs of surface stress should be evident if lithosphere uplift occurred. In the future, we hope to develop a more robust model: expanding to two dimensions, including other physical effects such as membrane stress and flexure, and further examining the stress and strain that a KREEP thermal anomaly could cause. | |
Cole Meyer | Spatial Heterodyne Interferometric Molecular Cloud Observer (SHIMCO): Target Selection and Spectral Modeling | Newly born stars radiate intense ultraviolet emission which dictates the physical properties of the molecular clouds in which the stars were born. Far-UV photons penetrate the outermost layers of those clouds and electronically excite H2 molecules within the clouds’ photodissociation regions, ultimately producing H2 fluorescence spectra which reflect the clouds' physical properties. Launching early 2027, the Spatial Heterodyne Interferometric Molecular Cloud Observer (SHIMCO) sounding rocket mission will observe H2 fluorescence spectra at higher resolving power (R>130,000) than any previous mission, allowing both relative line strengths and line shapes to be inferred. Crucially, relative line strengths and shapes independently reflect star formation and destruction rates and as such, SHIMCO will place tight constraints on the overall growth rate of the cloud. In spite of the abundance of possible cloud targets, SHIMCO’s short observing time (~7 minutes) requires us to prioritize only 2–3 of the brightest regions to maximize scientific return. We employ low resolution spectra from the FIMS-SPEAR instrument onboard STSAT-1 obtained between 2003 and 2004 alongside models of H2 fluorescence spectra to infer total irradiance from target candidates. By propagating those values through our modeled interferometer, we estimate exposure times needed to obtain the desired SNR for target candidates. These models will enable us to constrain possible SHIMCO targets and inform a priori exposure time estimates. | |
Lily Robinthal | Clearing the Air: Solar System Bodies as Windows into the Impact of Aerosols on Exoplanet Atmospheric Retrievals | Dust, hazes, and clouds are ubiquitous in the atmospheres of both solar system bodies and exoplanets. Understanding the impact of these aerosols on atmospheric spectra is key to deriving accurate information from exoplanet atmospheric retrievals. At present, these aerosols are heavily simplified in exoplanet inference models, which could limit model efficacy. Fortunately, we have the opportunity to use pre-existing solar system observations to validate and improve exoplanet-focused approaches to representing aerosol structures. We are deriving aerosol profiles from occultation data of solar system worlds with known atmospheric composition, such as Titan and Mars. These profiles provide an opportunity for ground-truth verification of exoplanet atmospheric characterization tools and allow us to improve our retrieval pipelines. We aim to understand if simplified model representations produce results that resemble real hazes and, if not, where we can improve, as well as determine what impact these simplifications have on retrievals. We use occultation data from Cassini’s UVIS instrument and MAVEN’s IUVS instrument to construct atmospheric profiles for Titan and Mars, respectively. Going forward, we will continue this process using occultation data of Venus, Earth, Saturn and Pluto to expand our catalog of ground-truth calibrations for models and retrieval pipelines. | |
Christina Singh | Sublimation Thermokarsts Reveal the Boulder Content of Mid-Latitude Ice on Mars | Decameters of near-subsurface water ice occur in some regions of the Martian midlatitudes, poleward of 30°N and 30°S latitude, and have been revealed by impact craters, erosional scarps, and sublimation thermokarst landforms also called “scallops”. The abundance of past and present ice is valuable for understanding the history of Martian climate conditions, habitability, future in situ resource utilization, and for the future of human exploration; thus, the need to characterize the formation and evolution of this ice and quantify its purity remains. High resolution (0.25–0.3 m/px) imagery from the High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO) is ideal for observing boulder populations on this periglacial terrain. We assess the boulder content within the ice by examining boulder distributions inside and outside scalloped depressions using the Rock Shadow Counter (ROSCO), a machine vision algorithm that utilizes rock shadows to determine the size and location of boulders. Preliminary results indicate that the surrounding plains contain the same or higher rock abundances than the scallops. We will study the morphology of these features (slopes, circularity, layering, depths, and uniformity), the local area surrounding these features, and other landforms in close proximity to determine if scallop boulder counts are associated with specific regional influences or triggers. | |
Robin Van Auken | Characterizing Callisto’s Brittle-Ductile Transition Through Multi-Ring Basin Graben Morphology | Landform geology on Callisto reflects the internal structure and heat flow of the ice shell, making it a valuable probe for investigating subsurface properties. In this study, we measure the widths of graben structures encircling three multi-ring impact basins on Callisto: Asgard, Valhalla, and Adlinda. Using dip angles derived from laboratory experiments and Anderson fault mechanics, we determine the intersection depths of opposing fault scarps, providing minimum estimates for the depth of the brittle-ductile transition. This analysis enables an approximation of the thickness of the elastic portion of the ice shell at the time and location of crater formation, offering insights into Callisto’s regional thermal history. |
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