Sazuna/UAT_keywords huggingface dataset:
Lake Stars as an Earth Analog for Europa's Manannán Crater Spider Feature. Jupiter's icy moon Europa is an ocean world that is a prime candidate in our search for potential extraterrestrial habitability and life beyond Earth. Europa's surface hosts many features proposed to originate from brine sources within its icy shell, which may represent the most accessible liquid water bodies within our solar system. An intriguing possible example is the asterisk-shaped "spider" at the center of Manannán crater, identified by the Galileo mission, for which we propose the informal name Damhán Alla. We present a new formation hypothesis for Damhán Alla based on morphological analysis and preliminary analog modeling. We suggest that the feature may originate from a process similar to that forming dendritic "lake stars;" seasonal features found on frozen ponds and lakes on Earth, but under elevated post-impact pressure and temperature conditions. We present laboratory experiments performed in a liquid nitrogen-cooled glove box at NASA's Jet Propulsion Laboratory, which indicate that similar patterns can form in Europa granular ice simulant under lower-temperature regimes expected after impact, and we present initial calculations to describe the hypothesized process.

Keywords: Ice physics, Laboratory astrophysics, Europa, Surface ices, Planetary science, Craters
SpinTrace: A Python Library to Study the Physical Properties of Small Bodies Using Survey-based Photometry. We present SPINTRACE, a Python tool developed to retrieve and process survey-based photometry for the detection of brightness variations—primarily, but not exclusively—due to asteroid rotation. Current implementation features a modular pipeline for downloading, calibrating, and analyzing point-spread function photometry from the Zwicky Transient Facility (ZTF), with support for phase curve modeling and periodicity searches, either across the entire dataset or within subsamples. It also uses parallelized downloading and local caching to improve performance. We applied SPINTRACE to two well-studied small bodies: the trans-Neptunian object and dwarf planet (136108) Haumea and the large Jupiter Trojan (624) Hektor. For Haumea, we obtained absolute magnitudes in each of the three Sloan Digital Sky Survey filters available within the ZTF survey, confirmed its rotational period of P = 3.915343 ± 0.00005 hr, and saw evidence of Hi'iaka's mutual orbit. Hektor is known for its elongated shape and exhibits significant changes in the amplitude of its rotational light curve over the ZTF time span. To display this variability, after obtaining the rotational period of P = 6.92025 ± 0.00027 hr, the dataset was divided into subsamples and individually analyzed. We recovered rotational light curves with amplitudes varying from 0.092 ± 0.028 mag in 2018, peaking at 1.135 ± 0.057 mag in 2021, and again decreasing to 0.070 ± 0.028 mag in 2025. SPINTRACE was designed in preparation for the upcoming 10 yr Legacy Survey of Space and Time conducted by the Vera Rubin Observatory, which is expected to yield thousands of multifilter photometric measurements per object annually.

Keywords: Open source software, Surveys, Jupiter trojans, Dwarf planets, Photometry, Trans-Neptunian objects
JWST/NIRSpec Observations of Salacia-Actaea and Máni: Exploring Population-level Trends among Water-ice-rich Kuiper Belt Objects. We present observations of the midsized Kuiper Belt objects (KBOs) Salacia─Actaea and Máni, obtained with the Near-Infrared Spectrograph on JWST. The satellite Actaea was fully blended with Salacia at the spatial resolution of the integral field unit, and we extracted the combined spectrum. The 0.7─5.1 μm reflectance spectra of Salacia─Actaea and Máni display prominent water-ice absorption bands at 1.5, 2, 3, and 4─5 μm. The ν3 fundamental vibrational band of carbon dioxide ice at 4.25 μm is present in both spectra. From a quantitative band-depth analysis of the entire current JWST spectroscopic sample of water-ice-rich KBOs, we find strong evidence for a positive covariance between relative water-ice abundance and size, which may indicate the emergent impacts of internal differentiation and cryovolcanic production of surface water ice on midsized KBOs. A detailed look at the distribution of 2 and 3 μm band depths suggests additional sources of variability, such as different water-ice grain sizes. In addition, we report an apparent transition in the carbon dioxide band depth at object diameters of roughly 300─500 km, with larger objects showing systematically weaker absorptions, although selection effects within the sample do not allow us to confidently distinguish between a size-dependent phenomenon and a correlation with dynamical class.

Keywords: James Webb Space Telescope, Surface composition, Kuiper belt, Trans-Neptunian objects
Visible-infrared Spectra of keV Electron Irradiated Cryogenic Salts with Implications for Europa Surface Composition. Visible to near-infrared spectral coloring of cryogenic halides, sulfates, their frozen brines, and sulfuric acid hydrate formed through one to tens of keV electron radiation can inform on the composition of Europa's surface. The visible wavelength spectra of some of these materials present potential matches to the color of Europa's leading and trailing hemispheres, while others are clear mismatches, and the infrared reflectance provides additional insights. Consistent with previous studies, irradiated anhydrous NaCl uniquely exhibits a color center near 460 nm. Cryogenic saturated and dilute brines of NaCl do not contain color centers, although each reddens almost identically to each other when irradiated. Hydrated MgCl2 and MgSO4 minerals and brines also redden but differently from NaCl brines. Partially desiccated and irradiated sulfates and sulfuric acid hydrate offer potential matches to both the leading and trailing hemispheres based upon their visible spectra. The significant spectral mismatch of hydrohalite, magnesium chlorides, iron-bearing chlorides, and iron-bearing sulfates in the visible as well as the infrared imply that they are not present at more than trace abundances. The most likely explanation for the visible and infrared reflectance spectra of Europa's surface is a small amount of desiccated NaCl with a larger quantity of hydrated magnesium sulfate and sulfuric acid. We infer the subsurface ocean of Europa has significant sulfates as well as some chlorides, with the relatively incompatible sulfates preferentially being dominating in the Europan crust.

Keywords: Surface processes, Surface composition, Galilean satellites, Europa
Retrograde Predominance of Small Saturnian Moons Reiterates a Recent Retrograde Collisional Disruption. We report the discovery and careful orbital determination of 64 new irregular moons of Saturn found in images taken using the Canada─France─Hawaii Telescope from 2019 to 2021, bringing the total number of Saturnian irregulars to 122. By more than doubling the sample of Saturnian irregular moon orbits, including pushing to smaller sizes, we can now see finer detail in their orbital distribution. We note the emergence of potential subgroups associated with each of Siarnaq and Kiviuq within the Inuit group. We find that in the inclination range 157∘─172∘, the ratio of smaller moons (diameters less than 4 km) to larger moons (diameters greater than 4 km) is significantly larger than that of any other inclination range in the retrogrades. We denote this subset of the Norse group as the Mundilfari subgroup after its largest member. The incredibly steep slope of the Mundilfari subgroup's size distribution, with a differential power law index of q = 6, strengthens the hypothesis in E. Ashton et al. that this subgroup was created by a recent catastrophic collision, &lt;108 yr ago.

Keywords: Irregular satellites, Saturnian satellites, Natural satellites (Solar system)
Prebiotic Chemistry Insights for Dragonfly: Thermodynamics of Amino Acid Synthesis in Selk Crater on Titan. Saturn's moon Titan presents a compelling test bed for probing prebiotic chemistry beyond early Earth. Impact-generated melt pools provide transient aqueous habitats in an otherwise cryogenic environment. We use Cantera equilibrium models to assess whether mixtures of hydrogen cyanide (HCN), acetylene (C2H2), and ammonia (NH3) can drive amino acid synthesis in Selk-sized craters. Across 21 amino acids (20 proteinogenic plus β-alanine), NH3-free systems yield only proline, alanine, and β-alanine, whereas adding as little as 1% NH3 (relative to H2O) renders almost the full suite accessible, with yields peaking at 2% and tapering thereafter. The NH3-free alanine result implies alternative pathways beyond classical Strecker or aminonitrile hydrolysis, suggesting acetylene, abundant on Titan but scarce on early Earth, as a plausible feedstock. We identify acrylonitrile (detected on Titan) as a thermodynamically favorable intermediate that can convert to alanine under aqueous conditions in an NH3-free pathway. For glycine and alanine production from nitrile hydrolysis, comparison with laboratory kinetics shows that our equilibrium models predict near-complete conversion, while observed rates yield only partial products over weeks. Yet estimated chemical equilibration times (years to centuries) are far shorter than melt lifetimes (≥103─104 yr), supporting plausibility of equilibrium in situ. These predictions are directly testable with the Dragonfly Mass Spectrometer, for which we recommend preflight standards to test proline, alanine, β-alanine, cysteine, and methionine. The first three offer the best chances for amino acid detection regardless of ammonia availability; the latter two offer diagnostic tools for determining the presence of reactive sulfur in postimpact Titan ponds.

Keywords: Chemical thermodynamics, Surface processes, Titan, Astrobiology, Craters
Beyond Point Masses. V. Weywot's Non-Keplerian Orbit. We present a detailed dynamical analysis of the Quaoar─Weywot system based on nearly 20 yr of high-precision astrometric data, including new Hubble Space Telescope observations and stellar occultations. Our study reveals that Weywot's orbit deviates significantly from a purely Keplerian model, requiring the inclusion of Quaoar's nonspherical gravitational field and center-of-body─center-of-light (COB-COL) offsets in our orbit models. We place a robust upper limit on Weywot's orbital eccentricity (e &lt; 0.02), substantially lower than previous estimates, which has important implications for the strength of mean-motion resonances acting on Quaoar's ring system. Under the assumption that Quaoar's rings lie in its equatorial plane, we detect Quaoar's dynamical oblateness, J2, at ∼2σ confidence. The low J2 value found under that assumption implies that Quaoar is differentiated, with a total bulk density of 1751 ± 13 (stat.) kg m−3. Additionally, we detect significant COB-COL offsets likely arising from latitudinal albedo variations across Quaoar's surface. These offsets are necessary to achieve a statistically robust orbit fit and highlight the importance of accounting for surface heterogeneity when modeling the orbits of dwarf planet moons. These findings improve our understanding of Quaoar's interior and surface while providing key insights into the stability and confinement mechanisms of its rings.

Keywords: Natural satellite dynamics, Asteroid satellites, Dwarf planets, Trans-Neptunian objects, Planetary interior, Orbit determination
Zonal Winds in Titan's Middle Atmosphere from a Stellar Occultation Observed with Keck Adaptive Optics. We present spatially resolved Keck/NIRC2 images of a stellar occultation by Titan on 2022 September 5 and compare them to predictions from concurrent Atacama Large Millimeter/submillimeter Array (ALMA) observations and a suite of general circulation model (GCM) simulations. ALMA data and GCM simulations can predict middle atmospheric zonal wind distributions, which in turn produce diagnostic occultation image sequences. We construct an occultation forward model using the temperature profile measured by the Huygens Atmospheric Structure Instrument, which is then distorted using latitudinal zonal wind profiles from the ALMA data or GCM simulations. The occultation forward model yields simulated light distributions around Titan's limb, which we compare directly to the light distributions observed during the occultation. The GCM zonal wind profile corresponding to slightly before the time of the stellar occultation provides the best overall match to the data. The ALMA wind profile provided the best match to the occultation data when only the ingress data were considered, but it did not perform as well when data from ingress and egress were combined. Our data support the presence of stronger winds in the southern hemisphere during late northern summer.

Keywords: Titan, Deconvolution, Adaptive optics, Radio telescopes, Stellar occultation, Ground-based astronomy, Doppler shift, Near infrared astronomy
Using SOFIA's EXES to Search for C<SUB>6</SUB>H<SUB>2</SUB> and C<SUB>4</SUB>N<SUB>2</SUB> in Titan's Atmosphere. In Titan's atmosphere, the chemistry of simple hydrocarbons (e.g., CH4 and C2H2) and nitrogen bearing species (e.g., N2 and CN) represents an important link between molecular species and the ubiquitous organic haze that gives Titan its characteristic orange hue. Here we present a new search for two previously undetected molecules, triacetylene (C6H2) and the gas phase dicyanoacetylene (C4N2), using the Echelon-Cross-Echelle Spectrograph instrument on board the Stratospheric Observatory for Infrared Astronomy aircraft. We do not detect these two molecules but determine upper limits for their mixing ratios and column abundances. We find the 3σ upper limits on the uniform volume mixing ratio (VMR) above 100 km for C6H2 to be 4.3 × 10−11, which is lower than the photochemical model predictions. This new upper limit suggests that the growth of linear molecules is inhibited. We also put a strict upper limit on the uniform VMR for gas phase C4N2 above 125 km to be 1.0 × 10−10. This upper limit is well below the saturation mixing ratio at this altitude for C4N2 and greatly limits the feasibility of C4N2 forming ice from condensation.

Keywords: Infrared spectroscopy, Titan, Infrared astronomy, Natural satellite atmospheres, Atmospheric composition
Simultaneous Detection of the Size and Velocity of the Largest Ejecta Particles with Velocities Exceeding 1 km s<SUP>−1</SUP>. Impact ejecta with velocities exceeding the escape velocity of planetary bodies become meteorites and dust particles in interplanetary space. We present a new method that allows simultaneous measurement of the size and velocity of the largest high-velocity ejecta. High-speed camera images revealed the time required for the ejecta to reach the secondary target, and ejecta size was determined after the experiment by analyzing the craters formed upon their impact on the secondary target. We defined the size─velocity relationships of submillimeter ejecta with velocities exceeding 1 km s−1, focusing on the largest detectable ejecta in our experiments. The results show that millimeter-sized meteoroids impacting the rocky surfaces of planetary bodies at 7 km s−1 eject particles up to a few tens of micrometers in size toward interplanetary space at velocities exceeding the escape velocity of the body, even when it is greater than 1 km s−1.

Keywords: Impact phenomena, Meteorites, Interplanetary dust, Experimental techniques
The Case for Continuing VIPER: A Critical Milestone on the Journey Back to the Moon. NASA's VIPER mission was designed to explore the Moon's south pole region, with a primary objective of identifying and characterising volatile compounds such as water ice. Despite having been fully built and having passed all preflight environmental testing, the mission was cancelled by NASA in 2024 July, and the rover remains in storage. In this paper we outline why it remains crucial that a route to flying this mission, such as that outlined by NASA in 2025 September, is found. These reasons include laying the groundwork for both US and international exploration and habitation of the Moon, the development of the lunar economy, and the eventual goal of human exploration of Mars.

Keywords: The Moon, Lunar regolith
SVD-accelerated T-matrix Method for Simulation of Scattering by Electrically Large Sphere Clusters and ISAR Imaging of Asteroid-like Bodies. China's Tianwen-2 mission will carry a radar to detect the internal structure of the asteroid 469219 Kamoʻoalewa. The model of scattering from the asteroid is important for the mission. Grid-based methods like the finite-element method or the method of moments are impractical for asteroid-scale targets, due to prohibitive meshing and memory demands. Modeling asteroids as sphere clusters enables faster scattering simulations with significantly lower resource usage. The multiple-sphere T-matrix method is a full-wave simulation technique for computing electromagnetic scattering by clusters of spheres. For electrically large sphere clusters, iterative solvers require a new linear solve at each incident angle, which is time-consuming. This paper proposes an optimization based on singular value decomposition. It extracts information from solutions at the preceding incident angles to provide a superior initial guess for the solution at the current angle. This reduces the number of iterations required for convergence, yields a fivefold speedup in an 82-sphere test case, and enables completion of more complex scattering problems within the same wall-clock time. The proposed method is validated against the conventional approach. Inverse synthetic aperture radar imaging simulations are performed for four cluster models of asteroid-like bodies, including monolithic structure, nested monolithic structure, rubble-pile structure, and rubble-pile structure with cores. Their characteristic radar signatures are analyzed, especially the effects of structural configuration on trail length and morphology. The simulations use the parameters of the Tianwen-2 low-frequency radar and will aid future structural characterization of asteroid-like bodies in the solar system.

Keywords: Near-Earth objects, Radar astronomy
Evaluating Lunar Crater Ejecta Maturation across Wavelengths. Ejecta blankets of young lunar craters provide an important window into the maturation processes of material at the lunar surface. As freshly exposed material degrades, the signature of that material changes in remote sensing data. Specific indices have been identified for a variety of lunar datasets that can be (at least nominally) correlated with crater age and material maturation. The most ubiquitous of these is the optical maturity, calculated using visible and near-infrared data from the Clementine mission. Newly acquired data of the lunar surface from the Kaguya Multiband Imager, the Diviner lunar radiometer, the Mini-RF radar, and the LROC WAC now allow us to explore maturity relationships at a variety of wavelength regions relative to these Clementine color data. Three initial "type example" craters show that expected behaviors can be tracked across wavelengths and crater ages. In particular, choosing values of specific maturity indices at the crater rim and one crater radius and two crater radii out from the rim allow tracking maturation behavior as a function of surface age. The general trends seen for three type example craters continue when a larger population is evaluated. Some complications do exist, however, and there is not always a perfect correlation across wavelength, which is likely due to time- and size-dependent maturation processes. These comparative analyses provide an important technique to evaluate relative ages and the rate of lunar material evolution.

Keywords: Impact phenomena, Ejecta, The Moon, Lunar impacts, Remote sensing
Doomed Worlds. II. Reassessing Suggestions of Orbital Decay for TrES-5 b. TrES-5 b is one of only three ultrahot Jupiters with suggestions of a possibly decreasing orbital period that have persisted through multiple independent analyses. While WASP-12 b's decreasing period is well explained by tidally induced orbital decay, and stellar acceleration has been proposed for WASP-4 b, the cause of the apparent trend for TrES-5 b has not been satisfactorily explained. This work extends the previous observations with 14 new ground-based transits from 2016 to 2024 and two newly published midtimes for data from 2007 and 2009. Four TESS sectors (75, 77, 82, and 84) have also been included for the first time. With the new data, the case for a decreasing orbital period is much weaker than before. The revised rate of period change,  Ṗ=−5.3±2.2msyr−1 , is less than half that found in previous work, and the preference for a quadratic over a linear model, as measured through ∆BICLQ, has been falling since 2020, with a current value of 11. Furthermore, these results are not robust to outliers; removing a single early transit midtime causes the effect to vanish (∆BICLQ = −1). Additionally, no significant periodic signals in the transit timing data are identified. The current data are well explained by a linear ephemeris.

Keywords: Transit photometry, Transit timing variation method, Photometry
Influence of Magnetosonic Waves on the Venusian Ionosphere: The Role of Electron Landau Heating. Plasma waves around terrestrial planets mediate energy transfer between electromagnetic fields and charged particles, significantly influencing the dynamics of their space plasma environments. While such interactions are well documented at Earth and Mars, their role at Venus remains uncertain due to sparse in situ measurements. Here we analyze a recently reported magnetosonic wave event at Venus detected by the Pioneer Venus Orbiter, characterized by large-amplitude (∼10 nT), quasi-perpendicular fluctuations that coincide with enhanced electron temperatures in the topside ionosphere. These waves, generated in the upstream, propagate through the low-density magnetosheath with negligible damping before impinging on the topside ionosphere. Numerical modeling shows that these waves can Landau resonate efficiently with ionospheric thermal electrons in the 0.01─0.1 eV range, increasing the local electron temperature by nearly a factor of 2 on a timescale of ∼10 minutes. Such heating may intensify the ambipolar electric field, consequently facilitating the escape of light ions.

Keywords: Space weather, Planetary ionospheres, Solar system terrestrial planets, Plasma physics