Sazuna/UAT_keywords huggingface dataset:
The Role of Sulfate in Cation Exchange Reactions: Applications to Clay-Brine Interactions on Mars. Phyllosilicates on Mars record a complex history of aqueous activity, including at Gale crater and Meridiani Planum, where stratigraphic differences in clay mineralogy have been recorded in outcrops that also contain calcium sulfate minerals. Thus, characterizing associations between phyllosilicates and calcium sulfates may provide constraints that are useful for constraining the geochemical environments that formed these outcrops. Previous studies have documented calcium sulfate precipitation as a result of clay-salt-atmospheric H2O interactions, but the compositions of brines throughout Mars' history would have depended on the volume of water available on the Martian surface. Variations in brine composition influence the type and extent of reactions between the brines and the minerals that they come in contact with. To better understand how clay-brine interactions affected near-surface mineral assemblages on Mars, we performed two sets of experiments. The first set of experiments examined the effect of differing total brine concentrations and the second set explored variations in Na+ and SO4 2- concentrations independently. The results of this study show that gypsum readily forms due to cation exchange between montmorillonite and Na2SO4 brines of any concentration, but only near-saturated MgSO4 brines produced gypsum, and these also produced higher quantities of epsomite. Additionally, we found that the amount of gypsum produced from clay-Na2SO4 brine reactions is more strongly influenced by SO4 2- than Na+ or Cl- concentrations. Understanding how rapidly gypsum forms as a product of clay-brine interactions, as well as the influence of SO4 2- on cation exchange, will aid interpretations of sediments and environments that are observed on Mars.

Keywords: Mars
Taxonomic Classification of Asteroids Using the KMTNet Multiband Photometry Data Set. We report the multiband photometry of asteroids observed over 14 nights from 2015 December to 2017 December using the Korea Microlensing Telescope Network telescopes with the taxonomic classification of those objects. The data set contains the photometry of 6793 asteroids in the Sloan Digital Sky Survey griz bands. Following the method of DeMeo &amp; Carry, we define classification criteria on the 2D color plane to assign nine taxonomic types (A, B, C, K, L&amp;D, O, S, V, and X) for the observed objects. We also determine asteroid taxonomy in the newly defined 3D color space as suggested by Roh et al. with seven distinct types based on their novel semisupervised machine-learning model. Both methods distinguish between the S type and others but have difficulty separating the X and C types due to their weak and indistinguishable features and broad distribution in the color spaces. The heliocentric distribution of the observed asteroids with their taxonomic assignments confirms similar trends in the previous works; the number of S types decreases, while the fraction of C types increases with the heliocentric distance in the main belt. On the other hand, the D type dominates in the Jupiter Trojans.

Keywords: Multi-color photometry, Asteroids, Classification, Asteroid surfaces
The Influence of Cloud Condensation Nucleus Coagulation on the Venus Cloud Structure. We present the Venus version of PlanetCARMA and demonstrate the significance of coagulation properties on the structure of the Venus cloud system. The composition of the smallest mode of particles in the Venus atmosphere, which likely serve as cloud condensation nuclei (CCN), is unknown. Here we demonstrate that a change in the ability of CCN to grow via coagulation in the Venus atmosphere can produce measurable short-term and long-term signatures in the Venus cloud structure. Specifically, we find that the existence of a population of CCN that is prevented from growing via coagulation will result in an overall reduced total cloud opacity and can, under some conditions, produce long-term (on the order of several hundred days) variations in both the photochemical cloud opacity (above 57 km) and the condensational cloud opacity (below 57 km). While we show that these variations do not appear to be the source of the short-timescale cloud opacity variations seen on the nightside near-infrared emission of Venus, it is possible that they may contribute to the longer-term variations seen over the 2.5 yr lifetime of the VIRTIS-M-IR instrument on Venus Express. We recommend further modeling studies to investigate wider ramifications of this behavior, as well as further laboratory studies to better constrain the microphysical properties of the aerosols that can make up the Venus clouds.

Keywords: Atmospheric clouds, Planetary atmospheres, Venus, Atmospheric composition, Atmospheric variability
Modeling the Formation of Selk Impact Crater on Titan: Implications for Dragonfly. Selk crater is an ~80 km diameter impact crater on the Saturnian icy satellite Titan. Melt pools associated with impact craters like Selk provide environments where liquid water and organics can mix and produce biomolecules like amino acids. It is partly for this reason that the Selk region has been selected as the area that NASA's Dragonfly mission will explore and address one of its primary goals: to search for biological signatures on Titan. Here we simulate Selk-sized impact craters on Titan to better understand the formation of Selk and its melt pool. We consider several structures for the icy target material by changing the thickness of the methane clathrate layer, which has a substantial effect on the target thermal structure and crater formation. Our numerical results show that a 4 km diameter impactor produces a Selk-sized crater when 5-15 km thick methane clathrate layers are considered. We confirm the production of melt pools in these cases and find that the melt volumes are similar regardless of methane clathrate layer thickness. The distribution of the melted material, however, is sensitive to the thickness of the methane clathrate layer. In the case of a 10-15 km thick methane clathrate layer, the melt pool appears as a torus-like shape that is a few kilometers deep, and as a shallower layer in the case of a 5 km thick clathrate layer. Melt pools of this thickness may take tens of thousands of years to freeze, allowing more time for complex organics to form.

Keywords: Impact phenomena, Planetary surfaces, Methane, Titan, Saturnian satellites
Grain Size Effects on Visible and Near-infrared (0.35-2.5 μm) Laboratory Spectra of Ordinary Chondrite and HED Meteorites. Remote spectral characterization of near-Earth asteroids (NEAs) relies on laboratory spectral calibration to constrain their surface composition, including mineral chemistry and relative mineral abundances. Often these calibrations are based on fine meteorite powders that are representative of regolith observed on large NEAs such as (433) Eros. However, spacecraft observations of smaller NEAs such as (25143) Itokawa, (101955) Bennu, and (162173) Ryugu show surfaces devoid of a thick layer of regolith and instead find variegated landscapes with millimeter-sized particles to meter-scale boulders. Here we present the results of a laboratory study to understand the effects of grain size on the spectral properties of meteorites and how this can impact ground-based characterization of NEAs. Our study focuses on ordinary chondrites (H, L, LL) and HED meteorites, as they comprise ~90% of all meteorites that fall on Earth. Compared to ordinary chondrites, the spectral band parameters of HED meteorites are less affected by changing grain size. Among the ordinary chondrites, LL chondrites are least affected, but the spectral band parameters and mineral chemistries and abundances for H and L chondrites are most affected by changing grain size. Grain size does not seem to have any significant effect on the taxonomic classification of our meteorite spectra. We also used the Hapke model to investigate trends in single-scattering albedo as a function of grain size and present equations to recover the grain size from a spectrum.

Keywords: Meteorites
Strong Depletion of <SUP>13</SUP>C in CO Induced by Photolysis of CO<SUB>2</SUB> in the Martian Atmosphere, Calculated by a Photochemical Model. The isotopic signature of atmospheric carbon offers a unique tracer for the history of the Martian atmosphere and the origin of organic matter on Mars. The photolysis of CO2 is known to induce strong isotopic fractionation of the carbon between CO2 and CO. However, its effects on the carbon isotopic compositions in the Martian atmosphere remain uncertain. Here, we develop a 1D photochemical model to consider the isotopic fractionation via photolysis of CO2, to estimate the vertical profiles of the carbon isotopic compositions of CO and CO2 in the Martian atmosphere. We find that CO is depleted in 13C compared with CO2 at each altitude, due to the fractionation via CO2 photolysis: the minimum value of the δ 13C in CO is about -170‰ under the standard eddy diffusion setting. This result supports the hypothesis that fractionated atmospheric CO is responsible for the production of the 13C-depleted organic carbon in the Martian sediments detected by the Curiosity Rover, through the conversion of CO into organic materials and their deposition on the surface. The photolysis and transport-induced fractionation of CO that we report here leads to a ~15% decrease in the amount of inferred atmospheric loss when combined with the present-day fractionation of the atmosphere and previous studies of carbon escape to space. The fractionated isotopic composition of CO in the Martian atmosphere may be observed by ExoMars Trace Gas Orbiter and ground-based telescopes, and the escaping ion species produced by the fractionated carbon-bearing species may be detected by the Martian Moons eXploration mission in the future.

Keywords: Planetary atmospheres
The Enigmatic Abundance of Atomic Hydrogen in Saturn's Upper Atmosphere. A planet's Lyα emission is sensitive to its thermospheric structure. Here we report joint Hubble Space Telescope and Cassini cross-calibration observations of the Saturn Lyα emission made 2 weeks before the Cassini grand finale. To investigate the long-term Saturn Lyα airglow observed by different ultraviolet instruments, we cross-correlate their calibration, finding that while the official Cassini/UVIS sensitivity should be lowered by ~75%, the Voyager 1/UVS sensitivities should be enhanced by ~20% at the Lyα channels. This comparison also allowed us to discover a permanent feature of the Saturn disk Lyα brightness that appears at all longitudes as a brightness excess (Lyα bulge) of ~30% (~12σ) extending over the latitude range ~5°-35° N compared to the regions at equator and ~60° N. This feature is confirmed by three distinct instruments between 1980 and 2017 in the Saturn north hemisphere. To analyze the Lyα observations, we use a radiation transfer model of resonant scattering of solar and interplanetary Lyα photons and a latitude-dependent photochemistry model of the upper atmosphere constrained by occultation and remote-sensing observations. For each latitude, we show that the Lyα observations are sensitive to the temperature profile in the upper stratosphere and lower thermosphere, thus providing useful information in a region of the atmosphere that is difficult to probe by other means. In the Saturn Lyα bulge region, at latitudes between ~5° and ~35°, the observed brightening and line broadening support seasonal effects, variation of the temperature vertical profile, and potential superthermal atoms that require confirmation.

Keywords: Interplanetary medium, Planetary ionospheres, Upper atmosphere, Solar ultraviolet emission, Atmospheric structure, Ultraviolet telescopes, Solar spectral irradiance, Planetary atmospheres, Flux calibration, Chemical kinetics, Radiative transfer, Space telescopes
Influences on Infrared Spectra of Benzene Ices for Titan, Comets, and Beyond: Annealings, Artifacts, and Isosbestic Points. Infrared (IR) spectra are needed for both laboratory and observational studies of extraterrestrial ices, both within the solar system, such as for trans-Neptunian objects, comets, and Titan, and in the interstellar medium. Here we present new transmission-IR measurements on solid benzene (C6H6), the simplest common aromatic compound. Spectra are shown with a greater combination of higher resolutions and temperatures than found in the literature. The influences of both warmings and annealings on amorphous benzene are described, and comparisons are made of the IR spectra of warmed and cooled crystalline benzene. Reversible variations with temperature are noted for several IR bands of crystalline benzene, with a suggestion for their use as a possible thermometer for remote sensing of extraterrestrial environments. Comparisons are made to both recent and older literature results, and an artifact produced by high vapor-phase condensation rates is identified. New density measurements are reported for crystalline benzene and used, along with IR-forbidden transitions, to identify amorphous and crystalline ices. It is suggested that differences in spectra of crystalline benzene ices at the same temperature do not necessarily imply partial crystallization.

Keywords: Interstellar molecules, Ice spectroscopy, Laboratory astrophysics, Molecular spectroscopy, Titan, Astrochemistry, Comets, Small molecules
Implications for the Formation of (155140) 2005 UD from a New Convex Shape Model. (155140) 2005 UD has a similar orbit to (3200) Phaethon, an active asteroid in a highly eccentric orbit thought to be the source of the Geminid meteor shower. Evidence points to a genetic relationship between these two objects, but we have yet to fully understand how 2005 UD and Phaethon could have separated into this associated pair. Presented herein are new observations of 2005 UD from five observatories that were carried out during the 2018, 2019, and 2021 apparitions. We implemented light curve inversion using our new data, as well as dense and sparse archival data from epochs in 2005-2021, to better constrain the rotational period and derive a convex shape model of 2005 UD. We discuss two equally well-fitting pole solutions (λ = 116.°6, β = -53.°6) and (λ = 300.°3, β = -55.°4), the former largely in agreement with previous thermophysical analyses and the latter interesting due to its proximity to Phaethon's pole orientation. We also present a refined sidereal period of P sid = 5.234246 ± 0.000097 hr. A search for surface color heterogeneity showed no significant rotational variation. An activity search using the deepest stacked image available of 2005 UD near aphelion did not reveal a coma or tail but allowed modeling of an upper limit of 0.04-0.37 kg s-1 for dust production. We then leveraged our spin solutions to help limit the range of formation scenarios and the link to Phaethon in the context of nongravitational forces and timescales associated with the physical evolution of the system.

Keywords: Light curves, Near-Earth objects, CCD photometry
Tethys's Heat Fluxes Varied with Time in the Ithaca Chasma and Telemus Basin Region. We investigated how lithospheric heat fluxes varied temporally and spatially on the Saturnian moon Tethys, focusing on the region of Ithaca Chasma that overprints Telemus Impact Basin. Our results, derived from flexure associated with Ithaca, indicate elastic thicknesses of 4.1 ± 0.3 km to 6.4 ± 0.4 km and heat fluxes ranging from 12 to 39 mW m-2 assuming a nonporous pure H2O ice lithosphere. Our results for Ithaca's south limb are similar to previous estimates within the north limb, indicating consistent heat fluxes across a large spatial extent in this area. However, our estimates are lower than those for the older Telemus Basin (&gt;60 mW m-2), revealing evidence that Tethys experienced a substantial temporal variation in heat fluxes in this region. Heat fluxes reflected by Ithaca are similar to previous estimates for Tethys's two youngest impact basins, Melanthius and Odysseus, suggesting that Ithaca may also be relatively young. If Tethys's lithosphere is porous, then our heat flux estimates for Ithaca Chasma drop to 12-38 mW m-2, 11-35 mW m-2, and 10-33 mW m-2 for 5%, 15%, and 25% porosities, respectively. If Tethys's lithosphere includes ~10% NH3-hydrates, then the estimates are 5-16 mW m-2, 5-15 mW m-2, 4-14 mW m-2, and 4-13 mW m-2 for 0%, 5%, 15%, and 25% porosities, respectively. Although we find that some ground-based reflectance spectra hint at 2.2 μm bands that may result from NH3-bearing species, the detected features are weak and may not result from surface constituents. Consequently, our heat flux estimates that assume a pure H2O ice lithosphere are likely more accurate.

Keywords: Ice spectroscopy, Planetary thermal histories, Planetary science, Saturnian satellites, Thermal properties (Ice)
Saturn's Seismic Rotation Revisited. Normal mode seismology is a promising means of measuring rotation in gas giant interiors, and ring seismology presents a singular opportunity to do so at Saturn. We calculate Saturn's normal modes of oscillation and zonal gravity field, using nonperturbative methods for normal modes in the rigidly rotating approximation, and perturbative methods for the shifts that Saturn's deep winds induce in the mode frequencies and zonal gravity harmonics. The latter are calculated by solving the thermogravitational wind equation in an oblate geometry. Comparing many such models to gravity data and the frequencies of ring patterns excited by Saturn's normal modes, we use statistical methods to estimate that Saturn's cloud-level winds extend inward along cylinders before decaying at a depth 0.125-0.138 times Saturn's equatorial radius, or 7530-8320 km, consistent with analyses of Cassini's gravity and magnetic field data. The seismology is especially useful for pinning down Saturn's poorly constrained deep rotation period, which we estimate at 2π/ΩS = 634.7 minutes (median) with a 5/95% quantile range of 633.8-635.5 minutes. Outstanding residuals in mode frequencies at low angular degree suggest a more complicated deep interior than has been considered to date. Smaller but still significant residuals at high angular degrees also show that our picture for the thermal, composition, and/or rotation profile in Saturn's envelope is not yet complete.

Keywords: Planetary rings, Solar system gas giant planets, Orbital resonances, Non-radial pulsations, Planetary science
GTasb3D: A Novel 3D Framework for Modeling Thermal Evolution and Rarefied Flows in Porous Active Small Bodies with Various Shapes. Volatiles in small bodies provide important clues to solar system evolution and are of in-situ-resource-utilization interest. Explicit modeling of small bodies' global thermophysical process is essential to assess volatiles' evolution and abundance. Previous numerical studies commonly use a finite difference/volume method, which has limited capability in simulating the interior thermal dynamics of small bodies with realistic shapes. Here we developed a novel 3D framework using the generalized finite difference method for modeling thermal evolution of active small bodies (GTasb3D). By fully solving the energy and mass conservation equations using a mesh-free, Cartesian-coordinate-based method, this framework can evaluate the heat and mass transport in a porous cometary body of various shapes. Several tests and comparisons with previous studies have been carried out to verify this framework's accuracy and efficiency. We show that the timescale to achieve thermal equilibrium and the global temperature distribution are in good agreement with previous theoretical and numerical estimates. The GTasb3D simulations show that ice sublimation mainly occurs near the ice front, and parts of the resulting vapor recondense beneath the ice front. The surface gas density dramatically decreases as the ice retreats. For a 1 km radius object located at 3 au with initially homogeneous dust-ice distribution, the depth to ice at the equator is &gt;~2 cm after ~10 yr, assuming that a dust mantle is left behind after ice depletion. At this stage, the global gas production rate is below the gas emission detection capability but is capable of lifting submillimeter-sized dust from the nucleus's near-subsurface.

Keywords: Asteroids, Small Solar System bodies, Physical properties (Ice), Comets, Comet interiors
Determination of 1929 Asteroid Rotation Periods from WISE Data. We used 22 μm (W4) Wide-field Infrared Survey Explorer (WISE) observations of 4420 asteroids to analyze lightcurves, and determined spin period estimates for 1929 asteroids. We fit second-order Fourier models at a large number of trial frequencies to the W4 data and analyzed the resulting periodograms. We initially excluded rotational frequencies exceeding 7.57 rotations per day (P &lt; 3.17 hr), which are not sampled adequately by WISE, and periods that exceed twice the WISE observation interval, which is typically 36 hr. We found that three solutions accurately capture the vast majority of the rotational frequencies in our sample: the best-fit frequency and its mirrors around 3.78 and 7.57 rotations per day. By comparing our solutions with a high-quality control group of 752 asteroid spin periods, we found that one of our solutions is accurate (within 5%) in 88% of the cases. The best-fit, secondary, and tertiary solutions are accurate in 55%, 27%, and 6% of the cases, respectively. We also observed that suppression of aliased solutions was more effective with nonuniform sampling than with quasi-uniform sampling.

Keywords: Asteroids, Time series analysis, Light curves, Asteroid rotation, Infrared photometry
Revealing the Interior Structure of Icy Moons with a Bayesian Approach to Magnetic Induction Measurements. Some icy moons and small bodies in the solar system are believed to host subsurface liquid water oceans. The interaction of these saline, electrically conductive oceans with time-varying external magnetic fields generates induced magnetic fields. Magnetometry observations of these induced fields in turn enable the detection and characterization of these oceans. We present a framework for characterizing the interiors of icy moons using multifrequency induction and Bayesian inference applied to magnetometry measurements anticipated from the upcoming Europa Clipper mission. Using simulated data from the Europa Clipper Magnetometer, our approach can accurately retrieve a wide range of plausible internal structures for Europa. In particular, the ocean conductivity is recovered to within ±50% for all internal structure scenarios considered, and the ocean thickness can be retrieved to within ±25 km for five out of seven scenarios. Characterization of the ice shell thickness to ±50% is possible for six of seven scenarios. Our recovery of the ice shell thickness is highly contingent on accurate modeling of magnetic fields arising from the interaction of Europa with the ambient magnetospheric plasma, while the ocean thickness is more modestly affected and the ocean conductivity retrieval is largely unchanged. Furthermore, we find that the addition of a priori constraints (e.g., static gravity measurements) can yield improved ocean characterization compared to magnetometry alone, suggesting that multi-instrument techniques can play a key role in revealing the interiors of Europa and other ocean worlds.

Keywords: Planetary interior, Europa, Markov chain Monte Carlo, Galilean satellites, Magnetic fields