Sazuna/UAT_keywords huggingface dataset:
Thermal Properties of 1847 WISE-observed Asteroids. We present new thermophysical model fits of 1847 asteroids, deriving thermal inertia, diameter, and Bond and visible geometric albedo. We use thermal flux measurements obtained by the Wide-field Infrared Survey Explorer (WISE) during its fully cryogenic phase, when both the 12 μm (W3) and 22 μm (W4) bands were available. We take shape models and spin information from the Database of Asteroid Models from Inversion Techniques (DAMIT) and derive new shape models through lightcurve inversion and combining WISE photometry with existing DAMIT lightcurves. When we limit our sample to the asteroids with the most reliable shape models and thermal flux measurements, we find broadly consistent thermal inertia relations with recent studies. We apply fits to the diameters D (km) and thermal inertia Γ (J m‑2 s‑0.5 K‑1) normalized to 1 au with a linear relation of the form  , where we find α = 2.667 ± 0.059 and β = ‑0.467 ± 0.044 for our sample alone and α = 2.509 ± 0.017 and β = ‑0.352 ± 0.012 when combined with other literature estimates. We find little evidence of any correlation between rotation period and thermal inertia, owing to the small number of slow rotators to consider in our sample. While the large uncertainties on the majority of our derived thermal inertia only allow us to identify broad trends between thermal inertia and other physical parameters, we can expect a significant increase in high-quality thermal flux measurements and asteroid shape models with upcoming infrared and wide-field surveys, enabling even more thermophysical modeling of higher precision in the future.

Keywords: Main belt asteroids, Astronomy data modeling, Asteroids
Mars Climate Sounder Observations of Gravity-wave Activity throughout Mars's Lower Atmosphere. Gravity waves are one way Mars's lower atmospheric weather can affect the circulation and even composition of Mars's middle and upper atmosphere. A recent study showed how on-planet observations near the center of the 15 μm CO2 band by the A3 channel (635-665 cm-1) of the Mars Climate Sounder on board the Mars Reconnaissance Orbiter could sense horizontally short, vertically broad gravity waves at ≈25 km above the surface by looking at small-scale radiance variability in temperature-sensitive channels. This approach is extended here to two additional channels closer to the wings of the 15 μm CO2 band, A1 (595-615 cm-1) and A2 (615-645 cm-1), to sense gravity waves throughout the lower atmosphere. Using information from all three channels demonstrates that gravity-wave activity in Mars's lowermost atmosphere is dominated by orographic sources, particularly over the extremely rough terrain of Valles Marineris. Much of this orographic population is either trapped or filtered in the lowest two scale heights, such that variations in filtering and nonorographic sources shape the gravity-wave population observed at 25 km above the surface. During global dust storms, however, gravity-wave activity in the first scale height decreases by approximately a factor of 2, yet trapping/filtering of what activity remains in the tropics substantially weakens. Exceptionally high radiance variability at night in the tropics during the less dusty part of the year is the result of observing mesospheric clouds rather than gravity waves.

Keywords: Mars, Planetary atmospheres, Atmospheric variability
The Case for a New Frontiers-Class Uranus Orbiter: System Science at an Underexplored and Unique World with a Mid-scale Mission. Current knowledge of the Uranian system is limited to observations from the flyby of Voyager 2 and limited remote observations. However, Uranus remains a highly compelling scientific target due to the unique properties of many aspects of the planet itself and its system. Future exploration of Uranus must focus on cross-disciplinary science that spans the range of research areas from the planet's interior, atmosphere, and magnetosphere to the its rings and satellites, as well as the interactions between them. Detailed study of Uranus by an orbiter is crucial not only for valuable insights into the formation and evolution of our solar system but also for providing ground truths for the understanding of exoplanets. As such, exploration of Uranus will not only enhance our understanding of the ice giant planets themselves but also extend to planetary dynamics throughout our solar system and beyond. The timeliness of exploring Uranus is great, as the community hopes to return in time to image unseen portions of the satellites and magnetospheric configurations. This urgency motivates evaluation of what science can be achieved with a lower-cost, potentially faster-turnaround mission, such as a New Frontiers-class orbiter mission. This paper outlines the scientific case for and the technological and design considerations that must be addressed by future studies to enable a New Frontiers-class Uranus orbiter with balanced cross-disciplinary science objectives. In particular, studies that trade scientific scope and instrumentation and operational capabilities against simpler and cheaper options must be fundamental to the mission formulation.

Keywords: Solar system planets, Uranian satellites, Planetary atmospheres, Planetary rings, Planetary magnetospheres, Planetary interior, Extrasolar gaseous giant planets, Uranus
New Constraints on Titan's Stratospheric n-Butane Abundance. Curiously, n-butane has yet to be detected at Titan, though it is predicted to be present in a wide range of abundances that span over 2.5 orders of magnitude. We have searched infrared spectroscopic observations of Titan for signals from n-butane (n-C4H10) in Titan's stratosphere. Three sets of Cassini Composite Infrared Spectrometer Focal Plane 4 (1050-1500 cm-1) observations were selected for modeling, having been collected from different flybys and pointing latitudes. We modeled the observations with the Nonlinear Optimal Estimator for MultivariatE Spectral AnalySIS radiative transfer tool. Temperature profiles were retrieved for each of the data sets by modeling the ν 4 emission from methane near 1305 cm-1. Then, incorporating the temperature profiles, we retrieved abundances of all of Titan's known trace gases that are active in this spectral region, reliably reproducing the observations. We then systematically tested a set of models with varying abundances of n-butane, investigating how the addition of this gas affected the fits. We did this for several different photochemically predicted abundance profiles from the literature, as well as for a constant-with-altitude profile. Ultimately, though we did not produce any firm detection of n-butane, we derived new upper limits on its abundance specific to the use of each profile and to multiple different ranges of stratospheric altitudes. These results will tightly constrain the C4 chemistry of future photochemical modeling of Titan's atmosphere and also motivate the continued search for n-butane and its isomer, isobutane.

Keywords: Planetary atmospheres, Titan, Solar system, Natural satellite atmospheres, Planetary science, Atmospheric composition, Saturnian satellites
Kronoseismology. VI. Reading the Recent History of Saturn's Gravity Field in Its Rings. Saturn's C ring contains multiple structures that appear to be density waves driven by time-variable anomalies in the planet's gravitational field. Semiempirical extensions of density wave theory enable the observed wave properties to be translated into information about how the pattern speeds and amplitudes of these gravitational anomalies have changed over time. Combining these theoretical tools with wavelet-based analyses of data obtained by the Visual and Infrared Mapping Spectrometer on board the Cassini spacecraft reveals a suite of structures in Saturn's gravity field with azimuthal wavenumber 3, rotation rates between 804° day-1 and 842° day-1, and local gravitational potential amplitudes between 30 and 150 cm2 s-2. Some of these anomalies are transient, appearing and disappearing over the course of a few Earth years, while others persist for decades. Most of these persistent patterns appear to have roughly constant pattern speeds, but there is at least one structure in the planet's gravitational field whose rotation rate steadily increased between 1970 and 2010. This gravitational field structure appears to induce two different asymmetries in the planet's gravity field, one with azimuthal wavenumber 3 that rotates at roughly 810° day-1 and another with azimuthal wavenumber 1 rotating three times faster. The atmospheric processes responsible for generating the latter pattern may involve solar tides.

Keywords: Saturn, Planetary atmospheres, Planetary rings, Solar system gas giant planets, Celestial mechanics, Stellar occultation, Wavelet analysis, Planetary interior
Arecibo S-band Radar Characterization of Local-scale Heterogeneities within Mercury's North Polar Deposits. Ground-based planetary radar observations first revealed deposits of potentially nearly pure water ice in some permanently shadowed regions (PSRs) on Mercury's poles. Later, the MESSENGER spacecraft confirmed the icy nature of the deposits, as well as their location within PSRs. Considering the geologic context provided by MESSENGER, we further characterized the north polar deposits by pairing spacecraft data with new Arecibo S-band radar observations. Here we show that some ice deposits within PSRs have a gradational pattern in their radar properties that is likely associated with differences in ice purity. Radar-bright features with a circular polarization ratio μ  c  &gt; 1 can be characterized by water ice with ≳3% impurities by volume while those with μ  c  &lt; 1 by ≳20% impurities. Furthermore, areas in PSRs with μ  c  &lt; 1 typically surround locations of stronger radar backscatter with μ  c  &gt; 1. Therefore, deposits of nearly pure water ice are likely surrounded by lower-purity material, such as water-ice-rich regolith, which could be the result of impact gardening or the crater's thermal environment. However, such deposits are not always colocated within large polar craters where ice should be the most stable, even at the surface. In fact, we found that there is no significant difference between the radar backscattering properties of deposits thought to have surficial ice and those with buried ice. Our results also help improve the identification of icy reservoirs elsewhere, such as the Moon. Indeed, we found that μ  c  is not an adequate diagnostic, but rather the radar backscatter in each circular polarization independently provides information to identify water-ice deposits.

Keywords: Surface ices, Planetary polar regions, Radar astronomy, Mercury (planet)
Compositional Maps of the Lunar Polar Regions Derived from the Kaguya Spectral Profiler and the Lunar Orbiter Laser Altimeter Data. Due to the challenging illumination conditions of the lunar polar regions, mineralogic maps have generally been constrained to within 0°-70°N/S. Here we generate a gridded reflectance data cube from the Kaguya Spectral Profiler measurements for each polar region and calibrate it to absolute reflectance using data from the Lunar Orbiter Laser Altimeter. We use this data set to derive the first quantitative mineral maps of iron oxide (FeO), the optical maturity parameter (OMAT), and nanophase iron poleward of 50°N/S at a spatial resolution of 1 km pixel-1. We evaluate potential latitudinal trends in space weathering and optical maturity and characterize the polar geology, with an emphasis on the Artemis region (84°-90°S). The maps of FeO are in excellent agreement with the abundances measured by the Lunar Prospector and provide an increased level of detail, such as the excavation of high- and low-FeO material by De Forest crater. The OMAT maps offer a fantastic view of both polar regions. They highlight small fresh craters, walls, and central peaks, as well as rays extending through multiple degrees of latitude, such as those from Tycho and De Forest, which extend into the Artemis region. Both polar regions are characterized by the ubiquitous presence of noritic anorthosites and anorthositic norite. Low-calcium pyroxene is largely the dominant mafic mineral present. The Artemis region has relatively homogeneous FeO and plagioclase content at the observed spatial resolution. The lowest FeO values are found near Shackleton, between Shoemaker and Faustini, and on the central peak of Amundsen crater.

Keywords: Lunar surface, Lunar mineralogy, Planetary science
Science Drivers for the Future Exploration of Ceres: From Solar System Evolution to Ocean World Science. Dawn revealed that Ceres is a compelling target whose exploration pertains to many science themes. Ceres is a large ice- and organic-rich body, potentially representative of the population of objects that brought water and organics to the inner solar system, as well as a brine-rich body whose study can contribute to ocean world science. The Dawn observations have led to a renewed focus on planetary brine physics and chemistry based on the detection of many landforms built from brines or suspected to be emplaced via brine effusion. Ceres' relative proximity to Earth and direct access to its surface of evaporites that evolved from a deep brine reservoir make this dwarf planet an appealing target for follow-up exploration. Future exploration, as described here, would address science questions pertinent to the evolution of ocean worlds and the origin of volatiles and organics in the inner solar system.

Keywords: Ceres, Dwarf planets, Surface ices
Orientale Ejecta at the Apollo 14 Landing Site Implies a 200-million-year Stratigraphic Time Shift on the Moon. Detailed spectral mapping, cratering statistics, and impact basin ejecta column estimates document a new and very different stratigraphic relationship for the Apollo 14 landing site. We observe a resurfacing event in the crater size-frequency distribution in agreement with a single blanketing layer. Using the crater size-frequency distribution, we determine two relative ages (cumulative crater frequencies) that match those observed for the Imbrium and Orientale basins, respectively. The pattern and strength of resurfacing and morphological distinction by spectral features suggest the top layer to be about 10-25 m thick. We propose that this top layer at the Apollo 14 landing site is Orientale basin ejecta above Imbrium basin ejecta. Such stratigraphy reattributes the (majority of) Apollo 14 samples to Orientale rather than to Imbrium basin and implies that Orientale basin is about 3.92 Gyr old, 200 million years older than previously suggested. The youngest lunar basin thus formed at the onset, rather than amid, of recorded mare volcanism. This time shift also changes constraints on early planetary and solar system processes, such as the intensity of impact bombardment, and pleads for revision of the crater-statistics-based surface ages of other planetary bodies.

Keywords: Selenology, Lunar surface, Lunar impacts, Lunar mineralogy
Blue Marble, Stagnant Lid: Could Dynamic Topography Avert a Waterworld?. Topography on a wet rocky exoplanet could raise land above its sea level. Although land elevation is the product of many complex processes, the large-scale topographic features on any geodynamically active planet are the expression of the convecting mantle beneath the surface. This so-called "dynamic topography" exists regardless of a planet's tectonic regime or volcanism; its amplitude, with a few assumptions, can be estimated via numerical simulations of convection as a function of the mantle Rayleigh number. We develop new scaling relationships for dynamic topography on stagnant lid planets using 2D convection models with temperature-dependent viscosity. These scalings are applied to 1D thermal history models to explore how dynamic topography varies with exoplanetary observables over a wide parameter space. Dynamic topography amplitudes are converted to an ocean basin capacity, the minimum water volume required to flood the entire surface. Basin capacity increases less steeply with planet mass than does the amount of water itself, assuming a water inventory that is a constant planetary mass fraction. We find that dynamically supported topography alone could be sufficient to maintain subaerial land on Earth-size stagnant lid planets with surface water inventories of up to approximately 10-4 times their mass, in the most favorable thermal states. By considering only dynamic topography, which has ~1 km amplitudes on Earth, these results represent a lower limit to the true ocean basin capacity. Our work indicates that deterministic geophysical modeling could inform the variability of land propensity on low-mass planets.

Keywords: Extrasolar rocky planets, Ocean planets, Exoplanet surface composition, Exoplanet surface variability, Exoplanet evolution, Habitable planets
Occultation Mapping of Io's Surface in the Near-infrared. I. Inferring Static Maps. With hundreds of active volcanoes varying in intensity on different timescales, Jupiter's moon Io is the most volcanically active body in the solar system. Io has been observed from Earth using high-cadence near-infrared photometry during occultations by Jupiter and other Galilean moons since the 1980s. These observations encode a wealth of information about the volcanic features on its surface. We built a generative model for the observed occultation light curves using the code starry, which enables fast, analytic, and differentiable computation of occultation light curves in emitted and reflected light. Using this model, we are able to recover surface thermal emission maps of Io containing known volcanic hot spots without having to make assumptions about the locations, shapes, or number of hot spots. Our model is also directly applicable to the problem of mapping the surfaces of stars and exoplanets.

Keywords: Bayesian statistics, Exoplanets, Occultation, Volcanoes, Io, Volcanism
Science Goals and Mission Concept for a Landed Investigation of Mercury. Mercury holds valuable clues to the distribution of elements at the birth of the solar system and how planets form and evolve in close proximity to their host stars. This Mercury Lander mission concept returns in situ measurements that address fundamental science questions raised by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission's pioneering exploration of Mercury. Such measurements are needed to understand Mercury's unique mineralogy and geochemistry, characterize the proportionally massive core's structure, measure the planet's active and ancient magnetic fields at the surface, investigate the processes that alter the surface and produce the exosphere, and provide ground truth for remote data sets. The mission concept achieves one full Mercury year (~88 Earth days) of surface operations with an 11-instrument, high-heritage payload delivered to a landing site within Mercury's widely distributed low-reflectance material, and it addresses science goals encompassing geochemistry, geophysics, the Mercury space environment, and geology. The spacecraft launches in 2035, and the four-stage flight system uses a solar electric propulsion cruise stage to reach Mercury in 2045. Landing is at dusk to meet thermal requirements, permitting ~30 hr of sunlight for initial observations. The radioisotope-powered lander continues operations through the Mercury night. Direct-to-Earth communication is possible for the initial 3 weeks of landed operations, drops out for 6 weeks, and resumes for the final month. Thermal conditions exceed lander operating temperatures shortly after sunrise, ending operations. Approximately 11 GB of data are returned to Earth. The cost estimate demonstrates that a Mercury Lander mission is feasible and compelling as a New Frontiers-class mission.

Keywords: Exosphere, Surface processes, Surface composition, Landers, Mercury (planet), Planetary magnetospheres, Planetary interior
Student Dust Counter Status Report: The First 50 au. The Venetia Burney Student Dust Counter (SDC) is an in situ dust detector on board the New Horizons spacecraft measuring the interplanetary dust particle (IDP) distribution for grains with mass m &gt; 10-12 g. SDC provides a near-continuous measure of the interplanetary dust environment, with recent results spanning beyond 50 au. This coverage includes the Edgeworth-Kuiper Belt (EKB), suggested by numerical models to be the dominant source of IDP in the outer solar system. Here we present the updated dust density distribution to 50 au and compare estimated flux values to existing theoretical models. SDC observes peak dust flux and densities near 42 au, and we expect a decay with increasing heliocentric distance. Based on SDC measurements, we also discuss the effects of IDP generation, transport, and loss on the evolution of the surfaces of EKB objects, the continual intermixing of their surface material, and the general tendency to homogenize their spectral properties. Continued SDC measurements remain critical for revealing the large-scale structure of the EKB and to guide the interpretation of dust disks around other stars. Additionally, we consider the potential of an interstellar dust (ISD) and "outer" Kuiper Belt contribution to SDC measurements and its effect on anticipated SDC flux values beyond 50 au, and we show that the inclusion of either source to the predicted model results in a noticeable deviation in anticipated SDC measurements beyond 50 au. Current and future SDC measurements also serve to constrain the relative contribution of ISD to SDC's flux and density estimates.

Keywords: Interplanetary dust, Kuiper belt
ASpatially Resolved Observations of Europa's Surface with Subaru/IRCS at 1.0-1.8 μm: Upper Limits to the Abundances of Hydrated Cl-bearing Salts. Recent infrared observations at 1.5-4.0 μm using large ground-based telescopes have suggested that Cl-bearing salts are likely present on Europa's surface as non-ice materials. The chemical compositions of those Cl-bearing salts are key to understanding Europa's ocean chemistry and habitability. Here we report the results of ground-based telescope observations of Europa across two wavelength ranges, 1.0-1.5 μm and 1.5-1.8 μm, of which the former range includes absorption features due to some hydrated Cl-bearing salts. We obtained spatially resolved reflectance spectra using the Subaru telescope/IRCS and the adaptive optics system AO188 with high wavelength resolutions (δλ ~ 2 nm for 1.0-1.5 μm and δλ ~ 0.9 nm for 1.5-1.8 μm) and low noise levels (1σ ~ (1-2) × 10-3). We found no clear absorption features at ~1.2 μm caused by hydrated Cl-bearing salts. We estimated that conservative upper limits to the abundances of MgCl2 · nH2O, NaClO4 · 2H2O, Mg(ClO3)2 · 6H2O, and Mg(ClO4)2 · 6H2O on Europa are 17% (&lt;10% for most) at the 3σ noise level. These values are lower than the proposed abundance of some hydrated Cl-bearing salts (&gt;~20%) on Europa based on previous observations. This supports the idea that Cl-bearing salts on Europa are likely anhydrous Na salts of NaCl and/or NaClO4, or hydrated NaCl · 2H2O. The presence of Na salts suggests that Na+ could be the major cation in Europa's ocean, which would be possible if the oceanic pH is circumneutral or alkaline.

Keywords: Planetary surfaces, Surface composition, Chemical abundances, Europa, Jovian satellites, Near infrared astronomy