Sazuna/UAT_keywords huggingface dataset:
The Distribution of Impactor Core Material During Large Impacts on Earth-like Planets. Large impacts onto young rocky planets may transform their compositions, creating highly reducing conditions at their surfaces and reintroducing highly siderophile metals to their mantles. Key to these processes is the availability of an impactor's chemically reduced core material (metallic iron). It is, therefore, important to constrain how much of an impactor's core remains accessible to a planet's mantle/surface, how much is sequestered to its core, and how much escapes. Here, we present 3D simulations of such impact scenarios using the shock physics code iSALE to determine the fate of impactor iron. iSALE's inclusion of material strength is vital in capturing the behavior of both solid and fluid components of the planet and thus characterizing iron sequestration to the core. We find that the mass fractions of impactor core material that accretes to the planet core (f core) or escapes (f esc) can be readily parameterized as a function of a modified specific impact energy, with ${f}_{\mathrm{core}}\gt {f}_{\mathrm{esc}}$ for a wide set of impacts. These results differ from previous works that do not incorporate material strength. Our work shows that large impacts can place substantial reducing impactor core material in the mantles of young rocky planets. Impact-generated reducing atmospheres may thus be common for such worlds. However, through escape and sequestration to a planet's core, large fractions of an impactor's core can be geochemically hidden from a planet's mantle. Consequently, geochemical estimates of late bombardments of planets based on mantle siderophile element abundances may be underestimates.

Keywords: Impact phenomena, Planetary science
The Unusual Brightness Phase Curve of (65803) Didymos. On 2022 September 26, NASA's Double Asteroid Redirection Test (DART) successfully hit Dimorphos, the smaller companion of the binary system formed with the asteroid (65803) Didymos. Both the binary system and the impact event were imaged by the Light Italian Cubesat for Imaging of Asteroids, detached from DART 15 days before the impact. Images from the onboard LUKE red, green, and blue camera together with ground-based observations enabled the reconstruction of Didymos's brightness phase curve, with phase angles ranging from 2.35° to 107.7°. The opposition effect regime was studied using the exponential-linear equation, the "Shevchenko" function and the linear-by-parts model while the IAU-official HG1G2 magnitude system was applied to the full phase curve. The opposition effect indicates an unusual asteroid surface for an S type, with characteristics similar to M-type asteroids. While the HG1G2 parameters from the full phase curve place Didymos well among asteroids of the taxonomic C complex. Didymos's phase curve parameters when compared to near-Earth asteroids are very close to the Q type (1862) Apollo, indicating possible depletion of fine submicrometric grains through resurfacing. Didymos's geometric albedo (0.15 ± 0.01) is reported to be 30%–45% smaller than the average geometric albedo for near-Earth S types (0.26 ± 0.04). We propose that Didymos might be an LL ordinary chondrite analog containing albedo-suppressing, shock-darkened/impact melt minerals that have undergone resurfacing processes in the past. A comparison with meteorites indicates that, less likely, Didymos could also contain materials analog to carbon-bearing brecciated L3 ordinary chondrites.

Keywords: Near-Earth objects, Phase angle, Asteroids, RGB photometry, Photometry, Asteroid surfaces
Rocks with Extremely Low Thermal Inertia at the OSIRIS-REx Sample Site on Asteroid Bennu. The Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) mission recently returned a sample of rocks and dust collected from asteroid Bennu. We analyzed the highest-resolution thermal data obtained by the OSIRIS-REx Thermal Emission Spectrometer (OTES) to gain insight into the thermal and physical properties of the sampling site, including rocks that may have been sampled, and the immediately surrounding Hokioi Crater. After correcting the pointing of the OTES data sets, we find that OTES fortuitously observed two dark rocks moments before they were contacted by the spacecraft. We derived thermal inertias of 100–150 (±50) J m‑2 K‑1 s‑1/2 for these two rocks—exceptionally low even compared with other previously analyzed dark rocks on Bennu (180–250 J m‑2 K‑1 s‑1/2). Our simulations indicate that monolayer coatings of sand- to pebble-sized particles, as observed on one of these rocks, could significantly reduce the apparent thermal inertia and largely mask the properties of the substrate. However, the other low-thermal-inertia rock that was contacted is not obviously covered in particles. Moreover, this rock appears to have been partially crushed, and thus potentially sampled, by the spacecraft. We conclude that this rock may be highly fractured and that it should be sought in the returned sample to better understand its origin in Bennu's parent body and the relationship between its thermal and physical properties.

Keywords: Near-Earth objects, Asteroids, Remote sensing, Planetary science, Asteroid surfaces
Catalog of Ultraviolet Bright Stars: Strategies for UV Occultation Measurements, Planetary Illumination Modeling, and Sky Map Analyses Using Hybrid IUE-Kurucz Spectra. Ultraviolet spectroscopy is a powerful method to study planetary surface composition through reflectance measurements, atmospheric composition through stellar/solar occultations, transits of other planetary bodies, and direct imaging of airglow and auroral emissions. The next generation of ultraviolet spectrographs (UVS) on board ESA's Jupiter Icy Moons Explorer and NASA's Europa Clipper missions will perform such measurements of Jupiter and its moons in the early 2030s. This work presents a compilation of a detailed UV stellar catalog, named Catalog of Ultraviolet Bright Stars (CUBS), of targets with high intensity in the 50–210 nm wavelength range with applications relevant to planetary spectroscopy. These applications include (1) planning and simulating occultations, including calibration measurements; (2) modeling starlight illumination of dark, nightside planetary surfaces primarily lit by the sky; and (3) studying the origin of diffuse Galactic UV light as mapped by existing data sets from Juno-UVS and others. CUBS includes observations from the International Ultraviolet Explorer (IUE) and additional information from the SIMBAD database. We have constructed model spectra at 0.1 nm resolution for almost 90,000 targets using interpolated Kurucz models (which have a resolution of 1 nm) and, when available, IUE spectra. CUBS also includes robust checks for agreement between the Kurucz models and the IUE data. We also present a tool for which our catalog can be used to identify the best candidates for stellar occultation observations, with applications for any UV instrument. We report on our methods for producing CUBS and discuss plans for its implementation during ongoing and upcoming planetary missions.

Keywords: Stellar occultation, Ultraviolet spectroscopy, Catalogs, Europa
Mini-RF S-band Radar Characterization of a Lunar South Pole–crossing Tycho Ray: Implications for Sampling Strategies. One of the youngest features on the Moon is Tycho, an 85 km diameter impact crater with a vast ray system that spans much of the lunar nearside. As such, it serves as an important stratigraphic marker for the Moon. One of Tycho's longest rays crosses the South Pole, where it intersects several candidate landing sites for NASA's Artemis III mission, which intends to return new lunar samples. Identification of ray-related effects are thus important to understand the provenance of collected material. To help contextualize sampling strategies, here we characterize the South Pole–crossing Tycho ray using monostatic S-band radar observations from the Lunar Reconnaissance Orbiter's Miniature Radio Frequency instrument. We found that the ray is a ∼15 km wide radar-bright feature extending at least ∼1600 km from Tycho. Polarimetric analysis revealed that the measured radar backscatter is consistent with a terrain enhanced in centimeter-to-decimeter-scale scatterers. Moreover, we found that the abundance of these scatterers likely decreases with distance from the primary crater, suggesting there may be less Tycho-disturbed material, in particular, poleward of 85°S, where the candidate landing sites are located. Nevertheless, we identified craters along the ray and, importantly, within the Haworth candidate landing site that exhibit secondary crater characteristics, such as radar-bright, asymmetric ejecta deposits. We showed, based on solar illumination and topographic slopes, that the likely Tycho-related secondaries within Haworth are accessible by landed missions. Exploration of this site may thus directly sample Tycho-disturbed material, including a nearby permanently shadowed region, providing new insights into lunar surface processes.

Keywords: Lunar surface, Radar observations, Lunar rays
Probing the Oxidation State of Ocean Worlds with SUDA: Fe (II) and Fe (III) in Ice Grains. Characterizing the geochemistry of Europa and Enceladus is a key step for astrobiology investigations looking for evidence of life in their subsurface oceans. Transition metals with several oxidation states, such as iron, may be tracers of the oxidation state of icy ocean moon interiors. Their detection, as well as the characterization of their oxidation states, on the moons' (plume) ice grains would bring valuable new information about the geochemistry of both the subsurface oceans and surface processes. Impact ionization mass spectrometers such as the SUDA instrument on board Europa Clipper can analyze ice grains ejected from icy moons' surfaces and detect ocean-derived salts therein. Here we record mass spectra analogs for SUDA using the Laser Induced Liquid Beam Ion Desorption technique for Fe2+ and Fe3+ salts (both sulfates and chlorides). We show that impact ionization mass spectrometers have the capability to detect and differentiate ferrous (Fe2+) from ferric (Fe3+) ions in both cation and anion modes owing to their tendency to form distinct ionic complexes with characteristic spectral features. Peaks bearing Fe3+, such as [Fe3+ (OH)2]+ and [Fe3+ (OH) a  Cl b ]‑, are particularly important to discriminate between the two oxidation states of iron in the sample. The recorded analog spectra may allow the characterization of the oxidation state of the oceans of Europa and Enceladus with implications for hydrothermal processes and potential metabolic pathways for life forms in their subsurface oceans.

Keywords: Mass spectrometers, Time-of-flight mass spectrometry, Enceladus, Europa, Astrobiology
Challenges in Identifying Artificial Objects in the Near-Earth Object Population: Spectral Characterization of 2020 SO. Since the dawn of the Space Age, hundreds of payloads have been launched into heliocentric space. As near-Earth object (NEO) surveys search deeper for small asteroids, more artificial objects in heliocentric orbits are being discovered. We now face a challenge to identify the true nature of these objects and avoid contaminating the NEO catalog. Here, we present the methods used to characterize one such object. 2020 SO was discovered by the Pan-STARRS1 survey on 2020 September 17. Originally classified as a NEO, the object's artificial nature became evident due to its low velocity relative to Earth and solar radiation pressure affecting its orbit about the Sun. Based on a backward propagation of its orbit, 2020 SO is thought to be a Centaur rocket body (R/B) from the launch of the Surveyor 2 mission to the Moon. We characterized 2020 SO using a range of ground-based optical and near-infrared telescopes to constrain its true nature. We find that its reflectance spectrum is consistent with that of other Centaur R/B launched during a similar time frame, and we identify 1.4, 1.7, and 2.3 μm absorption bands consistent with polyvinyl fluoride used on the aft bulkhead radiation shield exterior of Centaur-D R/B at the time.

Keywords: Artificial satellites, Near-Earth objects, Infrared spectroscopy, Asteroids
"Spiders" on the Moon: Morphological Evidence for Geologically Recent Regolith Drainage into Subsurface Voids. On the Moon, the surface morphology at the scale of meters and tens of meters is typically smooth and subdued due to regolith gardening. Sharp, "crisp," meter-scale morphologic features are observed only where the regolith is either thin or recently disturbed. Such crisp morphologies are typically created by geologically recent meteoritic impacts of different scales. The prominent exception is so-called irregular mare patches (IMPs), rare small features of debated origin. We report here on the discovery of previously unknown crisp immature morphological features (named "spiders" due to their central circular region and radiating "legs") not related to impacts and even more rare. The spiders are meters-deep depressions with near-radial chutes open toward the center which make an incipient dendritic pattern 50–80 m in diameter. All spiders found thus far occur in clusters in the same region in Mare Tranquillitatis in the immediate proximity to small IMPs. We interpret spiders as the result of an energetic granular flow of the regolith draining into shallow subsurface voids following the sudden collapse of the roofs of the voids. Regolith gardening destroys the spiders' legs rapidly, on a timescale of a million years. If the entrance into the subsurface void remains unclogged, a spider appears to evolve into a pit; otherwise it evolves into a gentle depression and finally disappears. Our interpretation of spiders provides a consistent explanation of all of their features, occurrence settings, and associations.

Keywords: Lunar surface
Measurements of Titan's Stratospheric Winds during the 2009 Equinox with the eSMA. Saturn's moon Titan possesses stratospheric zonal winds that places it among a sparse class of planetary bodies known to have superrotation in their atmospheres. Few measurements have been made of these speeds in the upper stratosphere, leaving their seasonal variations still not well understood. We examined observations made with the extended Submillimeter Array in 2009 March (L  s  = 355°) and 2010 February (L  s  = 5°), shortly before and after Titan's northern spring equinox. Cassini observations and atmospheric models find equinoctial periods to be especially dynamic. Zonal wind calculations, derived from the Doppler frequency shift of CH3CN near 349.4 GHz, yielded speeds of 128 ± 27 m s‑1 in 2009 and 209 ± 48 m s‑1 in 2010. We estimated the measured emission to originate from vertical altitudes of ${336}_{-88}^{+112}$ km, equivalent to pressures of ${3.8}_{-3.4}^{+19.2}$ Pa, commensurate with Titan's upper stratosphere/lower mesosphere. This suggests a possible increase in zonal speeds during this period. The results are then compared to those from previous Cassini-inferred and direct-interferometric observations of winds, as well as general circulation model simulations, to form a more complete picture of the seasonal cycle of stratospheric zonal winds.

Keywords: Radio astronomy, Titan, Planetary atmospheres, Natural satellite atmospheres, Planetary science, Submillimeter astronomy, Atmospheric dynamics, Saturnian satellites, Atmospheric variability
History of Ceres's Cold Traps Based on Refined Shape Models. Permanently shadowed regions (PSRs) in the north polar region of Ceres have been previously mapped by the Dawn spacecraft. Putative ice deposits are found in some of these PSRs, whereas most PSRs host no bright deposits, which is thought to be due to oscillations of the axis tilt with a ∼25 ka period. We use stereophotoclinometry to construct refined topographic models of PSR-hosting craters. Ray-tracing calculations reveal that no PSRs remain at the maximum axis tilt, which implies that the ice deposits are remarkably young. The bright ice deposits do not extend beyond PSRs at an axis tilt of 10°, which last occurred about 6 ka ago. This suggests that water is delivered to the polar regions or exposed within the craters by frequent and short-lived events. Surface temperatures are calculated with a terrain irradiance model to delineate cold traps. Based on maximum equilibrium temperatures, Cerean PSRs are too warm to trap supervolatiles.

Keywords: Ceres, Surface ices, Planetary polar regions
Three-dimensional Atmospheric Dynamics of Jupiter from Ground-based Doppler Imaging Spectroscopy in the Visible. We present three-dimensional (3D) maps of Jupiter's atmospheric circulation at cloud-top level from Doppler-imaging data obtained in the visible domain with JIVE, the second node of the JOVIAL network, which is mounted on the Dunn Solar Telescope at Sunspot, New Mexico. We report on 12 nights of observations between 2018 May 4 and May 30, representing a total of about 80 hr. First, the average zonal wind profile derived from our data is compatible with that derived from cloud-tracking measurements performed on Hubble Space Telescope images obtained in 2018 April from the Outer Planet Atmospheres Legacy program. Second, we present the first ever 2D maps of Jupiter's atmospheric circulation from Doppler measurements. The zonal velocity map highlights well-known atmospheric features, such as the equatorial hot spots and the Great Red Spot (GRS). In addition to zonal winds, we derive meridional and vertical velocity fields from the Doppler data. The motions attributed to vertical flows are mainly located at the boundary between the equatorial belts and tropical zones, which could indicate active motion in theses regions. Qualitatively, these results compare well to recent Juno data that have unveiled the 3D structure of Jupiter's wind field. To the contrary, the motions attributed to meridional circulation are very different from what is obtained by cloud tracking, except at the GRS. Because of limitations with data resolution and processing techniques, we acknowledge that our measurements of the vertical or meridional flows of Jupiter are still to be confirmed.

Keywords: Doppler imaging, Planetary atmospheres, Jupiter
Heat-flux-limited Cloud Activity and Vertical Mixing in Giant Planet Atmospheres with an Application to Uranus and Neptune. Storms operated by moist convection and the condensation of CH4 or H2S have been observed on Uranus and Neptune. However, the mechanism of cloud formation, thermal structure, and mixing efficiency of ice giant weather layers remains unclear. In this paper, we show that moist convection is limited by heat transport on giant planets, especially on ice giants where planetary heat flux is weak. Latent heat associated with condensation and evaporation can efficiently bring heat across the weather layer through precipitations. This effect was usually neglected in previous studies without a complete hydrological cycle. We first derive analytical theories and show that the upper limit of cloud density is determined by the planetary heat flux and microphysics of clouds but is independent of the atmospheric composition. The eddy diffusivity of moisture depends on the planetary heat fluxes, atmospheric composition, and surface gravity but is not directly related to cloud microphysics. We then conduct convection- and cloud-resolving simulations with SNAP to validate our analytical theory. The simulated cloud density and eddy diffusivity are smaller than the results acquired from the equilibrium cloud condensation model and mixing length theory by several orders of magnitude but consistent with our analytical solutions. Meanwhile, the mass-loading effect of CH4 and H2S leads to superadiabatic and stable weather layers. Our simulations produced three cloud layers that are qualitatively similar to recent observations. This study has important implications for cloud formation and eddy mixing in giant planet atmospheres in general and observations for future space missions and ground-based telescopes.

Keywords: Neptune, Atmospheric clouds, Planetary atmospheres, Solar system gas giant planets, Atmospheric dynamics, Uranus
Sulfur Implantation into Water Ice with Propane: Implications for Organic Chemistry on the Surface of Europa. We performed experiments of implantation of energetic sulfur ions (105 keV) into 2:1 water:propane ices at 80 K and analyzed the resulting refractory organic matter with ultrahigh-resolution mass spectrometry. Our goal was to characterize the organic matter processed in the surface conditions of Europa, where it would receive a heavy flux of energetic particles, including sulfur ions, and determine whether organosulfurs could be formed in these conditions, using the simplest alkane that can exist in solid form on Europa's surface. We find that the produced organic matter contains a large variety of both aliphatic and aromatic compounds (several thousand unique formulae), including polycyclic aromatic hydrocarbons (PAHs), with masses up to 900 amu. A large number of aromatic hydrocarbons is found along with oxygenated, mostly aliphatic, compounds. Organosulfurs are found in both CHS and CHOS form, demonstrating they can be formed from any organic compound through sulfur implantation. These organosulfurs' properties (aromaticity, mass) appear similar to the rest of the organic matter, albeit their low quantity does not allow for a thorough comparison. Our results have implications for the type of refractory organic matter that could be observed by the JUICE and Europa Clipper space missions and how the surface of Europa could generate complex organics, including PAHs and organosulfurs, that could then enrich the subsurface ocean. In particular, they indicate that a large diversity of organic matter, including organosulfurs, can be formed from simple precursors in a geologically short time frame under the ion flux that reaches Europa.

Keywords: Europa, Galilean satellites, Radiation interactions (Ice), Astrochemistry
VADER: Probing the Dark Side of Dimorphos with LICIACube LUKE. The ASI cubesat LICIACube has been part of the first planetary defense mission DART, having among its scopes to complement the DRACO images to better constrain the Dimorphos shape. LICIACube had two different cameras, LEIA and LUKE, and to accomplish its goal, it exploited the unique possibility of acquiring images of the Dimorphos hemisphere not seen by DART from a vantage point of view, in both time and space. This work is indeed aimed at constraining the tridimensional shape of Dimorphos, starting from both LUKE images of the nonimpacted hemisphere of Dimorphos and the results obtained by DART looking at the impacted hemisphere. To this aim, we developed a semiautomatic Computer Vision algorithm, named VADER, able to identify objects of interest on the basis of physical characteristics, subsequently used as input to retrieve the shape of the ellipse projected in the LUKE images analyzed. Thanks to this shape, we then extracted information about the Dimorphos ellipsoid by applying a series of quantitative geometric considerations. Although the solution space coming from this analysis includes the triaxial ellipsoid found by using DART images, we cannot discard the possibility that Dimorphos has a more elongated shape, more similar to what is expected from previous theories and observations. The result of our work seems therefore to emphasize the unique value of the LICIACube mission and its images, making even clearer the need of having different points of view to accurately define the shape of an asteroid.

Keywords: Near-Earth objects, Asteroids