Sazuna/UAT_keywords huggingface dataset:
Survival of Asteroid-sized Debris from the Moon-forming Impactor in Earth's Deep Mantle with Implications for Its Solar System Provenance. As the largest terrestrial planet in the solar system, Earth experienced a prolonged major accretion, ending with the Moon-forming giant impact (MFGI), whereas the direct evidence and origin of the impactor Theia remain elusive. Recent computational studies indicate that parts of the impactor Theia mantle may persist above Earth's core─mantle boundary as the large low-velocity provinces (LLVPs), yet it remains unclear how these results were affected by the initial size of Theia fragments after the MFGI. Here I explore such influence in whole-mantle convection simulations, assuming that the Theia debris size follows the size distribution of the main-belt asteroids, which provides a natural estimation of collision debris for the ill-constrained parameter during extreme impacts. The results demonstrate that the asteroid-sized Theia debris can survive Earth's 4.5-billion-year convective history as large-scale thermochemical structures resembling the seismically observed LLVPs. The results also demonstrate that rheologically strong Theia fragments are more capable of long-term preservation compared to those with weaker compositions. The inferred viscosity of Theia fragments aligns with that proposed for LLVPs from noble gas isotope evidence for a dry plume mantle source and agrees with global mantle attenuation constraints from seismic normal modes. These findings provide insight into the physical mechanism of preserving ancient geochemical signatures in Earth's mantle, support an inner solar system provenance for the impactor Theia, and further help explain the isotopic homogeneity between Earth and the Moon.

Keywords: Cosmochemistry, Asteroids, Planet formation, Earth (planet), Planetary interior, Earth-moon system
Evidence of Possible Spectral Variability in the Patroclus─Menoetius Binary System. We present new visible-wavelength spectroscopic observations of the Patroclus─Menoetius binary system in the Jupiter Trojan population. Motivated by previously published spectra from different instruments that showed evidence of significant longitudinal variability, we obtained two spectra spanning 440─680 nm at near-opposite rotational phases with the Gemini Multi-Object Spectrograph on the Gemini South telescope during the late 2024 apparition. The same solar analog was used for both observations to remove one source of inconsistency. We measured spectral slopes of 2.51% ± 0.05%/100 nm and 8.13% ± 0.05%/100 nm at the two different rotational phases. The first of these measurements was serendipitously obtained during an occultation of Menoetius by Patroclus. Although the statistical significance of the spectral slope discrepancy persists even after considering possible systematic errors stemming from differences in slit position angles and air masses between the asteroid and solar analog exposures, we consider this report of variability to be tentative. We briefly explore several scenarios that could explain the measured spectral slope variability. Additional follow-up observations are necessary to definitively confirm and characterize any inhomogeneities across the surface, which will have major implications for the 2033 flyby of Patroclus─Menoetius by the Lucy spacecraft.

Keywords: Jupiter trojans, Spectroscopy, Asteroid surfaces
Snowball Bistability Vanishes at Moderate Orbital Eccentricity. Snowball episodes are associated with increases in atmospheric oxygen and the complexity of life on Earth, and they may be essential for the development of complex life on exoplanets. Sustained, stable Snowball episodes require a Snowball bifurcation and climate bistability between the globally ice-covered Snowball state and a state with at least some open ocean. We find that climate bistability disappears for an aquaplanet with a slab ocean in the global climate model ExoCAM when the orbital eccentricity is increased to 0.2─0.3. This happens because the Snowball state ceases to exist as seasonal insolation variations intensify, while the warm state remains stable due to the ocean's large heat capacity. We use a low-order ice-thermodynamic model to show that the Snowball state ceases to exist as seasonality increases because winter freezing at the ice bottom is reduced relative to summer melting at the ice top due to ice self-insulation. Combined with previous research showing that Snowball climate bistability diminishes for planets orbiting low-mass stars and ones with longer rotation periods, and that it disappears entirely for tidally locked planets, our work suggests that the Snowball climate bistability may not be as robust to planetary parameters as previously thought, representing one aspect of habitability more consistent with the rare Earth hypothesis than the Copernican principle.

Keywords: Planetary climates, Habitable planets, Exoplanets
TRIDENT Ice Mining Drill for Lunar Volatile Prospecting for PRIME-1 and VIPER Missions. The Regolith and Ice Drill for Exploration of New Terrains (TRIDENT) is a 1 m class drill developed for capturing regolith and ice during the Volatiles Investigating Polar Exploration Rover (VIPER) and the Polar Resources Ice Mining Experiment (PRIME-1) lander missions to the south pole of the Moon. The drill employs decoupled rotation and percussion mechanisms to allow for three modes: rotation, percussion, and rotation─percussion, depending on operational goals and the material strength. TRIDENT can be operated in such a way that it can characterize subsurface material and deliver cuttings to the surface for characterization by other instruments. TRIDENT includes a drill-bit-integrated temperature sensor and an auger-integrated heater with a colocated temperature sensor 35 cm above the bit for thermal conductivity measurement. The heater can also be used in cases of ice adherence (freezing in) and to enhance the sublimation of ice from the cuttings pile. TRIDENT collects and delivers subsurface regolith onto the surface using a "bite" sampling approach: cuttings are captured in the auger flutes, the auger is retracted after drilling a 10 cm bite, and then 10 cm worth of cuttings are deposited onto the surface, forming a cuttings cone. This regolith cone is then analyzed by instruments Mass Spectrometer Observing Lunar Operations (MSOLO) and NIRVSS on the VIPER and MSOLO on the PRIME-1 missions. The drilling activity creates a seismic signal that can be detected on any associated inertial measurement unit that is turned on during the activity, which enables seismic science. TRIDENT represents two decades of technology development for planetary applications and could be deployed on any future missions to other solar system bodies. TRIDENT on the PRIME-1 mission has been successfully deployed in horizontal orientation (this orientation was due to the lander being in an off nominal landing orientation). All actuators, sensors, and heaters worked as designed. Even though the drill did not penetrate regolith, it was covered in regolith that fell onto the drill during the landing operation. VIPER is scheduled to launch to the Moon at the end of 2027 on Blue Origin's Mk1 lander.

Keywords: The Moon
Functionality of Ice Line Latitudinal EBM Tenacity (FILLET). Protocol Version 1.1. The Functionality of Ice Line Latitudinal EBM Tenacity (FILLET) project is a CUISINES exoplanet model intercomparison project that compares various energy balance models (EBMs) through a series of numerical experiments. The objective is to establish rigorous protocols that enable the identification of intrinsic differences among EBMs that could lead to model-dependent results for past, current, and future EBM studies. Such efforts also provide the community with an EBM ensemble average and standard deviation, rather than a single model prediction, on benchmark cases typically used by EBM studies. These experiments include Earth-like planets at different obliquity, instellation, and CO2 abundance. Here we update the v1.0 protocol to accommodate the requirements of previously untested community models. In particular, we expand the range of CO2 abundances for Experiment 4 to ensure any code will capture both snowball and ice-free end states. Additionally, participants are now required to report two ice edge latitudes per hemisphere to fully distinguish all climate states (snowball, ice caps, ice belts, and ice-free). The outputs described in FILLET protocol version 1.0 have also now been revised to include the maximum and minimum ice extent, in latitude, for each hemisphere, as well as the diffusion coefficient and outgoing longwave radiative flux.

Keywords: Planetary atmospheres, Exoplanet atmospheres
The Geology of a Small Main-belt S-class Binary Asteroid System: Dinkinesh and Its Contact Binary Satellite Selam as Observed by the Lucy Mission. The Lucy spacecraft flew past the ∼738 m diameter, S-class main-belt asteroid (152830) Dinkinesh on 2023 November 1, revealing a satellite named Selam. We used images acquired during the flyby to evaluate surface features on both Dinkinesh and Selam. We find a shallow crater size─frequency distribution (SFD) for Dinkinesh, consistent with crater SFDs observed on other subkilometer asteroids. We derive crater depth-to-diameter ratios near 0.1, also consistent with typical values seen on other asteroids. We calculate a cumulative boulder SFD for Dinkinesh with power-law index 3.93 ± 0.15 slightly steeper though in the range of other S-class asteroids. We find growing evidence that boulder SFDs are, on average, steeper for S-class than C-complex asteroids. Two major surface features on Dinkinesh, Sumak Fossa (a large trough) and Fab Dorsum (an equatorial ridge), are likely an outcome of YORP spinning up Dinkinesh fast enough to produce failure. A self-consistent structure for Dinkinesh that complies with the global shape, feature morphologies, and the estimated 10─20 Myr YORP spin-up timescale is a rubble-pile object with a nearly strengthless surface and an interior strength that is less than tens of Pa. Selam could have formed via YORP-driven mass shedding from Dinkinesh, though other formation mechanisms are possible. Combining a low-strength surface with the crater population and an impact model, we estimate a ∼1 Myr surface age for Dinkinesh. The presence of mass wasting and young troughs indicates that stress accumulation and release continue on Dinkinesh to the present day.

Keywords: Asteroids, Craters, Planetary geology
Orbital Decay Candidates Reconsidered: WASP-4 b Is Not Decaying and Kepler-1658 b Is Not a Planet. The fate of hot Jupiters is thought to be engulfment by their host stars, the outcome of tidal orbital decay. Transit timing has revealed a few systems with apparently shrinking orbital periods, but such signals can be mimicked by light travel-time effects (LTTE) of a distant companion. By combining transit timings with precise radial-velocity data, including new data, we reassessed three reported cases of orbital decay: WASP-4, WASP-12, and Kepler-1658. For WASP-4, the period change is best explained by LTTE due to an ≍7 MJup companion at ≍8 au, with no need to invoke orbital decay. For WASP-12, in contrast, the data firmly exclude LTTE and confirm genuine orbital decay. For Kepler-1658, spectroscopic and photometric anomalies reveal the "planet" to be an eclipsing K/M binary bound to the F-type primary, with LTTE explaining the observed period change. Thus, among the known hot Jupiters, only WASP-12 b currently shows compelling evidence for orbital decay.

Keywords: Exoplanet dynamics, Tidal interaction, Radial velocity, Hot Jupiters
Surface Response of Mercury's Sulfides under Solar Wind Ion Irradiation. The MESSENGER mission revealed unexpectedly high sulfur content within Mercury's surface, deviating from the lunar regolith, which was until recently considered a good Mercury analog. Mercury's exposure to energetic space weathering processes suggests that this high sulfur concentration should be reflected in the Hermean exosphere. UV spectroscopy has not yet detected exospheric sulfur, and future detection by BepiColombo's Mass Spectrum Analyzer depends on the exospheric sulfur abundance. Radiation-induced segregation has been observed in the common sulfide troilite (FeS), where the resulting metal cap is expected to reduce sulfur ejection to Mercury's exosphere. We investigate the irradiation response of Mercury-relevant niningerite (MgS) and oldhamite (CaS). The sulfides were irradiated with solar wind speed 2 keV  H2+  or 4 keV He+, and in situ compositional and chemical bond analysis was performed using an X-ray photoelectron spectroscopy microprobe. Neither MgS nor CaS expressed detectable radiation-induced segregation and instead reached metal-to-sulfur ratios close to bulk with irradiation. This agrees with a preexisting stability hypothesis based on the enthalpy of atomization. This hypothesis is, however, not always applicable, although comprehensive and accurate thermodynamic data are lacking. Based on the structural information of sulfides with known irradiation behavior, we inferred that an S─S anionic spacing exceeding ∼3.2 Å inhibits radiation-induced sulfur depletion. We predict no cation surface segregation in Hermean sulfides and no reduction in suprathermal sulfur emission caused by metal cladding formation in Ti, Mn, Cr, and Ca─Mg sulfides. This radiation hardness for Mercury-relevant sulfides is novel and unexpected and should facilitate detection in Mercury's exosphere by the BepiColombo mission.

Keywords: Solid matter physics, Experimental data, Exosphere, Solar wind, Mineral physics, Mercury (planet)
A New Global Perspective on Recent Tectonism in the Lunar Maria. Earth's Moon exhibits evidence that it is tectonically active. That evidence includes the Apollo Lunar Seismic Experiment detection of shallow moonquakes and the presence of geologically young tectonic features at the lunar surface. Lobate scarps are one such group of young tectonic features that are well studied and widespread across the lunar highlands. A separate, more recently identified class of young tectonic features on the lunar surface are the small mare ridges (SMRs). The SMRs appear to be formed in a similar timeframe as lobate scarps, but until recently, their global distribution and contribution to global lunar strain have remained unknown. Here we present the first global map and analysis of lunar SMRs. We demonstrate that SMRs are geologically young, formed via shallow-rooted thrust faults, and are widespread globally across the lunar maria. We also present an SMR fault displacement─length analysis and estimates of recent contractional strain in the lunar maria. Additionally, our results provide a new inventory of possible shallow lunar moonquake epicenters that are relevant to upcoming lunar exploration and landing site selection.

Keywords: Lunar maria, The Moon, Tectonics
A Multiarc Approach to Detecting Uranus's Normal Modes via Doppler Tracking of a Planetary Orbiter. Gravity science investigations as part of the Uranus Orbiter and Probe (UOP) mission concept are recommended to address key knowledge gaps in our understanding of Uranus's internal structure. Measurements of the planet's static gravity field and tidal parameters may be insufficient to fully constrain its mass distribution and core structure, hence complementary approaches are being considered, including the investigation of normal modes via planetary seismology. These global-scale oscillations, observed in Saturn and possibly Jupiter, are linked to interior properties and may be observable using a gravity science instrument. Yet, Uranus's mode frequencies and amplitudes remain unknown, posing a challenge for their detection. Here, we draw comparisons with Saturn's observed oscillations and perform numerical simulations of the UOP orbit determination process. The goal is to assess the minimum number of Uranus periapses necessary to detect the presence of normal modes as a function of orbiter trajectory. We do not attempt here to determine how precisely their amplitudes and frequencies can be estimated. We find that if Uranus's oscillations produce gravitational potential amplitudes comparable to those inferred for Saturn from Cassini ring seismology, an orbiter is likely to detect their signal after a few low-altitude periapses, for modes with angular degree ℓ &lt; 5. Detecting the signal of higher-degree modes (5 &lt; ℓ &lt; 10) is more challenging if the number of periapses is fewer than eight, as their gravitational potential rapidly weakens with distance and the limited data may be insufficient to accumulate a detectable signature.

Keywords: Gravitational fields, Planetary interior, Uranus
Miscibility of Hydrogen Sulfate Planetary Ionic Liquids with Water. Hydrogen sulfate protic ionic liquids may exhibit exceptional stability under warm, low-pressure planetary conditions, where conventional solvents would evaporate, making them plausible persistent fluids on sulfur-rich planetary surfaces. Yet their physicochemical behavior under hydration remains poorly constrained. We investigate glycinium hydrogen sulfate ionic liquid [GlyH+][ HSO4− ] mixed with 0%─80% water by volume using infrared spectroscopy, cryogenic electron microscopy (cryo-EM), and molecular dynamics simulations. We identify two distinct phases separated by a critical transition at ∼3 water molecules per ion pair (35% v/v water). Below this threshold, water molecules integrate into ionic liquid polar domains without disrupting  HSO4− ─ HSO4−  hydrogen-bonded networks, maintaining a homogeneous phase visible by cryo-EM. Above this threshold, the mixture undergoes phase inversion, forming 10 ± 2 nm ionic liquid aggregates dispersed in continuous water. Infrared spectroscopy reveals a sharp decrease in the strong/weak hydrogen bonding ratio at this transition point. At 70% water, cryo-EM shows uniform spherical nanodomains, each containing ∼3100 ion pairs with hydrated shells surrounding neat ionic liquid cores. Molecular dynamics simulations confirm spontaneous segregation into pure water regions and intact ionic liquid domains separated by interfacial zones. These findings demonstrate that hydrogen sulfate ionic liquids exposed to episodic water on planetary surfaces would persist as functional nanoscale compartments rather than fully mixing and dissolving in water. Our work has implications for planetary solvent availability, solute aggregation, and prebiotic chemistry in nonaqueous brines.

Keywords: Surface processes, Habitable planets, Pre-biotic astrochemistry
NEOWISE Data and Thermophysical Modeling of 98943 Torifune (2001 CC<SUB>21</SUB>). The Hayabusa2♯ flyby target 98943 Torifune (2001 CC21) has an uncertain size based on an uncertain albedo and absolute magnitude. We have collected all the NEOWISE observations of 2001 CC21 from 2021 November through 2024 February, a total of 132 frames, and analyzed these data to estimate an infrared radiometric diameter. We analyze the multiepoch 3.4 and 4.6 μm NEOWISE data using an ellipsoidal, rotating, cratered thermophysical model (TPM) to obtain estimates for the diameter, rotation pole, shape, and thermal inertia. 2001 CC21 is quite faint at 4.6 μm when ∆ ∼ 0.7 au, so the resulting diameter is substantially smaller than the 700 m derived from the H magnitude and L spectral type. Recent polarimetric data have also suggested a smaller diameter, but not quite as small as the diameter derived from the thermal IR data. A fit to an ellipsoidal TPM model gives a volume-equivalent sphere diameter of  337−27+33  m (posterior median and central 68% confidence interval). Prograde rotation with an obliquity of  (24−9+6)°  is preferred. We also applied this TPM to the Spitzer data presented by S. Fornasier et al. and obtained a diameter of 476% ± 9% m, which is consistent with the NEATM modeling presented by Fornasier et al. but with more realistic error bars. Finally, fitting the NEOWISE and Spitzer data together requires unexpectedly large thermal inertias and gives a bimodal posterior diameter distribution.

Keywords: Near-Earth objects, Asteroids
Activity of Halley-type Comets 12P/Pons─Brooks and 13P/Olbers from SOHO/SWAN Observations. The Solar Wind ANisotropies (SWAN) all-sky hydrogen Lyα camera on the Solar and Heliosphere Observatory (SOHO) observed the hydrogen coma of Halley-type comet (HTC) 12P/Pons─Brooks from SOHO's halo orbit around L1 throughout its 2023─2024 apparition from the beginning of 2023 November to just before the mid-November outburst. There was a gap in coverage during December and January when the comet was in the galactic plane, after which coverage then continued until 29 July. SWAN also observed another HTC comet, 13P/Olbers, from 2024 April 26 until 9 August. Water production rates were calculated from each image of both comets using the standard methodology with fluorescence rates calculated using the daily solar Lyα fluxes from the LASP database corrected for solar rotation. The water production rate of 12P reached a maximum of 1.7 × 1030 s−1 7 days before the comet perihelion on 2024 April 21. Eight outbursts were detected with released water masses from 4.66 × 108 to 8.06 × 109 kg. The comet's water production rate varied with heliocentric distance (r) with an exponent of −2.5 before perihelion and −2.9 after, covering heliocentric distances from 2.747 au before perihelion to 1.861 au after, when the activity is driven by water sublimation. The maximum production rate of 13P/Olbers was 1.1 × 1029 s−1, reached 27 days before perihelion on 2024 June 30. Its variation with heliocentric distance was more irregular and very scattered compared to that of 12P but generally increased with decreasing heliocentric distance. The variation of activity for 12P was generally very similar to that of the more famous HTC, 1P/Halley, in that both vary with heliocentric distance more similarly to most long-period Oort cloud comets than to most Kuiper belt Jupiter-family comets, many of which vary with very large negative slopes.

Keywords: Ultraviolet sources, Comae, Comets, Comet origins, Comet volatiles
Crater-based Dating of Hebrus Valles and Hephaestus Fossae, Mars. Hebrus Valles (HV) and Hephaestus Fossae (HF) are connected outflow channel systems in Utopia Planitia, Mars. Previous investigations concluded that these features were carved by liquid water into a tectonically fractured terrain in the Late Hesperian or Early Amazonian (&gt;3 Ga). However, their formation ages were poorly constrained. We use crater-based surface dating to determine model ages of the Utopia Planitia geologic units incised by HV and HF. For these units, we obtain model formation ages of  μ3.6−0.07+0.06 ─ μ3.1−0.3+0.2  Ga and model resurfacing ages of  μ2.1−0.2+0.2 ─ μ1.8−0.1+0.2  Ga, where μ represents uncertainties in absolute model age calibration. Using the buffered crater counting method, we also obtain model ages of  μ2.2−0.4+0.4  Ga and  μ1.9−0.3+0.4  Ga for the channels, coinciding with the peak of volcanic activity in the neighboring Elysium province. This confirms that Mars had geologically recent (Amazonian period), volcanically driven outflow channel activity, with implications for climate and habitability.

Keywords: Impact phenomena, Planetary surfaces, Surface processes, Mars, Remote sensing, Astrobiology, Planetary science, Planetary climates, Craters, Volcanism