Sazuna/UAT_keywords huggingface dataset:
Ground-based Characterization of (98943) Torifune 2001 CC<SUB>21</SUB>, the Target of the Hayabusa2# Space Mission. The near-Earth asteroid (98943) Torifune, previously designated 2001 CC21, is the flyby target of the Hayabusa2 extended mission, nicknamed Hayabusa2# (Small Hazardous Asteroid Reconnaissance Probe (SHARP)). The ground-based telescope observations offer a key science input for the mission's scientific investigation. During 2022–2024, this asteroid was at visible apparent magnitudes brighter than 18.5, allowing for a detailed characterization using ground-based telescope observations. We determined its rotation period P = 5.021516 ± 0.000106 hr and its absolute magnitude H = 18.78 ± 0.14. The large number of light curves allows us to estimate its axis ratio, its convex shape, and its pole orientation, λ = 301∘ ± 35∘,  , and ϵ = 5∘ ± 3∘, respectively, which indicate a prograde rotation. We report the semiaxis of the equivalent ellipsoid, a = 0.42  km, b = 0.16  km, and c = 0.17 ± 0.03 km. Consequently, the volume-equivalent diameter is Deq = 0.44 ± 0.06 km. Using observations conducted simultaneously with four broadband filters, we determined (g ‑ r) = 0.663 ± 0.022 mag, (r ‑ i) = 0.177 ± 0.012 mag, and (i ‑ zs) = ‑0.061 ± 0.032 mag. Additionally, we found that Torifune exhibits no detectable large-scale heterogeneity. We classified the object using a high signal-to-noise ratio spectrum (over the visible and near-infrared region) as Sq-type in the Bus–DeMeo taxonomy. We estimate a mineralogy similar to LL/L ordinary chondrites, with an ol/(ol+px) = 0.60, a Fa content of 28.5 mol%, and a Fs content of 23.4 mol%. The spectral data indicate a surface affected by moderate space weathering effects. *Based on observations made with the Two-meter Twin Telescope (TTT) and the Telescopio Carlos Sanchez (TCS) in the Spanish Observatorio del Teide, the Gran Telescopio Canarias (GTC) telescope and the Isaac Newton Telescope (INT) in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, and the NASA Infrared Telescope Facility (NASA IRTF) at the Maunakea Observatory in Hawaii.

Keywords: Observational astronomy, Near-Earth objects, Asteroid rotation, Spectroscopy, Spectrophotometry
Observations of Loki Patera by Juno during Close Flybys. We used data from the Juno spacecraft to investigate both the spatial and temporal properties of Loki Patera on Io, acquired in two infrared bands between 2022 December and 2024 April, at pixel sizes ranging from 400 m to 15 km. Loki shows a thermal structure unlike other active lava lakes previously reported, with some brightening near the lake's perimeter but lacking the continuous "hot ring" seen at other paterae. Modeling the slow rate of cooling suggests there is a significant volume of magma beneath the crust to provide the latent heat necessary to decelerate the cooling. A thermal propagation that may represent the signature of a resurfacing wave, going from the southwest of the lake to the north, was observed with a velocity of ∼2─3 km day−1. Data collected in 2024 may indicate the onset of a new resurfacing wave originating from a point source, rather than the foundering of a linear section of the crust. We also observed many small (∼3 km wide), closely spaced (∼10 km apart) islands that have persisted in the same locations for at least 45 years, since first being imaged by Voyager 1. The persistence of these islands challenges resurfacing models of Loki, as they have remained fixed—likely anchored to the lava lake floor—and have not noticeably changed in size, arguing against large-scale thermal erosion. The central island of Loki shows a few thermal structures associated with the fractures that cross the island, indicating that the fractures most likely contain molten lava.

Keywords: Io, Volcanism
Viability of the Early JUICE Flyby Trajectories to Confirm Ocean Existence at Ganymede. Ganymede is the largest moon in our solar system, and unique in producing its own magnetic field, as well as possibly possessing a subsurface ocean. The data analysis from the Galileo spacecraft provided two models for the internal field—a dipole and quadrupole model or a dipole and induction model. The latter model is preferred due to the number of parameters being less than the former, given that the model discrepancy with respect to the measurements is similar for both. While the recently launched JUpiter ICy moons Explorer (JUICE) mission will focus on Ganymede in its orbital phase providing an in-depth analysis, there are flybys initially around the moon that can be used for internal field studies. We focus on the first three close flybys of the mission in order to assess how effective the expected observation would be for distinguishing between the induction and quadrupole signals and confirm the existence of an ocean. We begin with an analysis of the JUICE and Galileo trajectories in different reference frames and predict the induction signal using the time varying field of Jupiter. A comparison between the two signatures for Galileo flybys agrees with previous results indicating induction to be present. Finally, we display and discuss the feasibility and importance of the three JUICE flybys to observe the induction field and hence confirm the ocean.

Keywords: Ocean planets, Ganymede, Jupiter, Magnetic fields, Planetary interior
THUNDER: A Titan Orbiter Mission Concept for the New Frontiers Program Designed at the JPL Planetary Science Summer School. Saturn's moon Titan is an enigmatic icy world whose surface is constantly modified by its active, Earthlike precipitation system. Here, we propose the Titan's Hydrocarbons: Uncovering New Dimensions of Evolutionary pRocesses (THUNDER) mission concept to investigate how Titan's surface reflects the nature of its interior and its active hydrocarbon cycle. This mission will change our understanding of Titan's surface through three science objectives: characterizing the heat and material transport properties of Titan's icy outer layer, tracing surface liquid storage through and across the crust, and assessing the total hydrocarbon budget through time. This New Frontiers-class mission, designed as part of the Jet Propulsion Laboratory Planetary Science Summer School, responds directly to the call for a Titan orbiter in the NASA Planetary Science and Astrobiology Decadal Survey 2023–2032. THUNDER's focused geology and geophysics mission could achieve full surface mapping to complement both the Cassini–Huygens and Dragonfly missions using gravity science, radar with three operational modes, and a visible-to-infrared spectrometer. These instruments together could give us the first look at Titan as a fully connected and geologically active world, revolutionizing our understanding of icy bodies, fluvial and atmospheric processes, and habitability across geologic time. Here, we summarize the goals of the science mission and engineering approaches, as well as challenges and future directions to study before THUNDER can become a viable mission concept.

Keywords: Orbiters, Natural satellite surfaces, Titan, Radar observations, Planetary science, Natural satellite evolution
Laboratory Study of Dust Mobilization on Airless Planetary Bodies in the Solar Wind Plasma. Dust charging, and the subsequent mobilization and transport, have been suggested to explain a number of unresolved and unusual features observed on airless planetary surfaces. These processes are also critical for understanding and mitigating potential dust hazards to human and robotic exploration on the lunar surface. A patched charge model (PCM), developed from recent laboratory and theoretical studies, shows that secondary electrons and/or photoelectrons absorbed inside microcavities between dust particles on the surface of airless bodies can accumulate unexpectedly large negative charges, causing dust mobilization and lofting due to strong repulsive forces. Complementary to previous work with secondary electrons induced by an electron beam and/or photoelectrons induced by ultraviolet (UV) radiation, here we present dust mobilization due to ion-induced secondary electrons in a simulated solar wind plasma with the energies of nitrogen ions in the range of 100–1000 eV. It is shown that dust mobility is correlated with the secondary electron emission that is determined by the energy- and material-dependent emission yield, as well as the electrostatic potential profile developed above the surface. Our results provide a new charging mechanism by the solar wind plasma based on the PCM, which is expected to play an important role in dust mobilization in permanently shadowed regions, where the solar wind ions can be diverted onto areas that are not accessible to UV radiation.

Keywords: Dust physics, Lunar surface
How CO Affects the Composition of Titan's Tholins Generated with Electron Cyclotron Resonance Plasma. Titan's atmosphere possesses thick haze layers, but their formation mechanisms remain poorly understood, including the influence of oxygen-containing gas components on organic matter synthesis. As the most abundant oxygen-containing gas, the presence of   has been found to exert a significant impact on the generation of oxygen-containing organic compounds. Therefore, investigating the influence of   on the production and composition of tholins through laboratory simulations holds profound scientific significance in the context of Titan. The work presented here is an experimental simulation designed to evaluate the impact of   on the atmospheric chemistry of Titan. To this end,   was introduced into the standard   mixture at varying mixing ratios from 0.2% to 9% and exposed to electron cyclotron resonance plasma to initiate photochemical reactions. Optical emission spectroscopy was employed for gas-phase in situ characterization, while infrared spectroscopy and high-resolution mass spectrometry were used to analyze the resulting solid products (tholins). Our results demonstrate that the addition of   enriches the complexity of the chemical system.   not only supplies oxygen to the system but also enhances nitrogen's reactivity and incorporation, enhancing the number and quantity of the organic products.

Keywords: Mass spectrometry, Titan, Experimental techniques, Natural satellite atmospheres, Astrobiology, Atmospheric composition, Pre-biotic astrochemistry
Stellar Occultation Observations of (38628) Huya and Its Satellite: A Detailed Look into the System. The physical and orbital parameters of trans-Neptunian objects provide valuable information about the solar system's formation and evolution. In particular, the characterization of binaries provides insights into the formation mechanisms that may be playing a role at such large distances from the Sun. Studies show two distinct populations, and (38628) Huya occupies an intermediate position between the unequal-sized binaries and those with components of roughly equal sizes. In this work, we predicted and observed three stellar occultation events by Huya. Huya and its satellitewere detected during occultations in 2021 March and again in 2023 June. Additionally, an attempt to detect Huya in 2023 February resulted in an additional single-chord detection of the secondary. A spherical body with a minimum diameter of D = 165 km can explain the three single-chord observations and provide a lower limit for the satellite size. The astrometry of Huya's system, as derived from the occultations and supplemented by observations from the Hubble Space Telescope and Keck Observatory, provided constraints on the satellite orbit and the mass of the system. Therefore, assuming the secondary is in an equatorial orbit around the primary, the limb fitting was constrained by the satellite orbit position angle. The system density, calculated by summing the most precise measurement of Huya's volume to the spherical satellite average volume, is ρ1 = 1073 ± 66 kg m‑3. The density that the object would have assuming a Maclaurin equilibrium shape with a rotational period of 6.725 ± 0.01 hr is ρ2 = 768 ± 42 kg m‑3. This difference rules out the Maclaurin equilibrium assumption for the main body shape.

Keywords: Natural satellites (Solar system), Solar system, Trans-Neptunian objects
Vertical and Temporal H<SUB>3</SUB><SUP>+</SUP> Structure at the Auroral Footprint of Io. We report the first observation of the vertical and temporal structure of the H3+ emission at the auroral footprint of Io, as observed by Juno/JIRAM. The brightness vertical profile shows a maximum at 600 km above 1 bar, with no apparent difference between the main Alfvén wing (MAW) spot emission and the tail of the footprint. This observation better aligns with a broadband energy distribution of the precipitating electrons, instead of a monoenergetic one. The temporal profile of H3+ column density has been observed after the passage of the MAW and shows a hyperbolic decrease. A model of H3+ decay is proposed, which takes into account the second-order kinetics of dissociative recombination of H3+ ions with electrons. The model is found to be in very good agreement with Juno observations. The conversion factor from radiance to column density has been derived, as well as the half-life for H3+, which is not constant but inversely proportional to the H3+ column density. This explains the wide range of H3+ lifetimes proposed before.

Keywords: Aurorae, Jupiter, Near infrared astronomy
Investigating Temporal and Spatial Variation of Jupiter's Atmosphere with Radio Observations. We study the spatial and temporal variability in Jupiter's atmosphere by comparing longitude-resolved brightness temperature maps from the Very Large Array radio observatory and NASA's Juno spacecraft Microwave Radiometer taken between 2013 and 2018. Spatial variations in brightness temperature, as observed at radio wavelengths, indicate dynamics in the atmosphere as they trace spatial fluctuations in radio-absorbing trace gases or physical temperature. We use four distinct frequency bands, probing the atmosphere from the water cloud region at the lowest frequency to the pressures above the ammonia cloud deck at the highest frequency. We visualize the brightness temperature anomalies and trace dynamics by analyzing the shapes of brightness temperature anomaly distributions as a function of frequency in Jupiter's North Equatorial Belt (NEB), Equatorial Zone (EZ), and South Equatorial Belt (SEB). The NEB has the greatest brightness temperature variability at all frequencies, indicating that more extreme processes are occurring there than in the SEB and EZ. In general, we find that the atmosphere at 5 and 22 GHz has the least variability of the frequencies considered, while observations at 10 and 15 GHz have the greatest variability. When comparing the size of the features corresponding to the anomalies, we find evidence for small-scale events primarily at the depths probed by the 10 and 15 GHz observations. In contrast, we find larger-scale structures deeper (5 GHz) and higher (22 GHz) in the atmosphere.

Keywords: Radio astronomy, Planetary atmospheres, Jupiter
Rover Science Autonomy in Planetary Exploration: Field Analog Tests. A strategy for planetary exploration using a rover capable of science autonomy is presented. We encoded into a rover a set of driving hypotheses pertaining to the geologic origin of a field site and equipped the rover with the instrumentation needed to measure the observables related to the hypotheses, as well as the software tools to analyze them to a relatively high level of confidence. We investigated the effects of different exploration strategies that make use of rover science autonomy and compared the operational efficiency and science yield of three geological exploration scenarios: (1) standard human-directed exploration, (2) rover-directed exploration, and (3) astronaut/rover collaborative exploration. We show that exploration with a rover capable of science autonomy is operationally more efficient than the human-directed strategy, resulting in higher rates of data collection and hence a greater science yield per command cycle. Additionally, we explored and developed astronaut/rover collaborative exploration strategies and present a basic framework for effective planetary exploration that leverages the expertise of a science team, the efficiency of a science-autonomous rover, and the contextual abilities of astronauts.

Keywords: Rovers
Kiladze Caldera: A Possible Cryovolcano on Pluto. In contrast with regional primarily methane composition, Kiladze and its surroundings exhibit a water-ice spectral signature that carries an ammoniated compound, similar to two other cryovolcanic sites on Pluto. The faulted structure of Kiladze, including shaping by numerous collapse pits and the distortion of the shape of the depression, are compatible with the surroundings in Hayabusa Terra, east of Sputnik Planitia. They are further compatible with an interpretation as a caldera formed during an era of an active cryovolcanic period that appears to be significantly more recent than the overall age of the planet's surface, possibly in the last several million years. In view of the size of the caldera and the large scale of the surrounding distribution of water ice, we suggest that Kiladze may have been a cryovolcano, in which one or more explosive events may have erupted ∼1000 km3 of icy cryomagma onto the surface.

Keywords: Volcanoes, Pluto
Beyond Point Masses. IV. Trans-Neptunian Object Altjira Is Likely a Hierarchical Triple Discovered through Non-Keplerian Motion. Dynamically studying trans-Neptunian object (TNO) binaries allows us to measure masses and orbits. Most of the known objects appear to have only two components, except (47171) Lempo, which is the single known hierarchical triple system with three similar-mass components. Though hundreds of TNOs have been imaged with high-resolution telescopes, no other hierarchical triples (or trinaries) have been found among solar system small bodies, even though they are predicted in planetesimal formation models such as gravitational collapse after the streaming instability. By going beyond the point-mass assumption and modeling TNO orbits as non-Keplerian, we open a new window into the shapes and spins of the components, including the possible presence of unresolved "inner" binaries. Here we present evidence for a new hierarchical triple, (148780) Altjira (2001 UQ18), based on non-Keplerian dynamical modeling of the two observed components. We incorporate two recent Hubble Space Telescope observations, leading to a 17 yr observational baseline. We present a new open-source Bayesian point-spread function fitting code called nPSF that provides precise relative astrometry and uncertainties for single images. Our non-Keplerian analysis measures a statistically significant (∼2.5σ) nonspherical shape for Altjira. The measured J 2 is best explained as an unresolved inner binary, and an example hierarchical triple model gives the best fit to the observed astrometry. Using an updated non-Keplerian ephemeris (which is significantly different from the Keplerian predictions), we show that the predicted mutual event season for Altjira has already begun, with several excellent opportunities for observations through ∼2030.

Keywords: Orbital motion, Occultation, Trans-Neptunian objects
Measuring the Effects of Regolith Porosity on Mid-IR Spectra of the Allende Meteorite. Mid-infrared (MIR; 5–35 μm) spectroscopy of laboratory meteorites does not often match asteroid spectra, making it difficult to constrain the parent bodies of meteorites using the MIR. To potentially improve the number of meteorite–asteroid matches, we simulated the effects of regolith porosity on the MIR spectra of the Allende meteorite. We separated a sample of Allende into three particle sizes (&lt;63 μm) and mixed them with various amounts of potassium bromide (KBr). We then collected MIR spectra of the KBr-mixed Allende samples, defined spectral features that may be indicative of composition and regolith porosity, and analyzed how the parameters of the spectral features (e.g., position and spectral contrast) changed with increasing regolith porosity. The Allende spectra show a transition from surface scattering to volume scattering as regolith porosity increases. Comparing to an olivine sample analyzed the same way shows that the opaque minerals in Allende may not have a significant effect on regolith porosity in the MIR. Finally, we present the MIR spectral analysis of four asteroids measured from the Spitzer Space Telescope: (114) Kassandra, (234) Barbara, (5261) Eureka, and (85989) 1999 JD6. We find that Kassandra and Barbara have high total porosities with some evidence of olivine, and Eureka and 1999 JD6 have low total porosities, with Eureka having strong evidence of olivine and 1999 JD6 having little evidence of olivine. This work shows how measuring MIR spectra of KBr-diluted particulate meteorites improves our ability to interpret the surface compositions and regoliths of asteroids from telescopic MIR spectra.

Keywords: Asteroids, Infrared spectroscopy, Carbonaceous chondrites, Spectral energy distribution, Spectroscopy, Meteorites, Asteroid surfaces
Spectroscopic Analysis of Ca–Sr, Ba–Sr, and Ca–Ba Sulfate Solid Solutions for In Situ Observations on Mars. Calcium sulfates are widely distributed in Gale crater and Endeavour crater on Mars. However, the mole ratios of Ca2+ and SO3 in some Sr–Ba-rich sulfate veins are less than 1. This indicates that there may be additional solid solution phases on Mars, including Ca–Sr, Ba–Sr, and Ca–Ba sulfates, which, on Earth, are typically found in marine environments. In this study, we synthesized a series of Ca–Sr, Ba–Sr, and Ca–Ba sulfate solid solutions in the laboratory. These synthesized solid solutions were then characterized using various techniques, including X-ray powder diffraction (XRD), Raman, mid-infrared, and visible and near-infrared. Our results show that the XRD and Raman spectra of Ca–Sr and Ba–Sr sulfates varied with their cation contents. In particular, the linear relationships (R2 ≥ 0.98) between the mole ratios of cation ions and peak positions of   tetrahedron (v1) in Raman spectra were obtained. The mole content of Ca2+, Sr2+, and Ba2+ can be precisely constrained in Ca–Sr, Ba–Sr, and Ca–Ba sulfate solid solution phases through linear relationships, respectively. These results are the experimental basis for analyzing in situ detection data (e.g., SHERLOC, SuperCam, and Oxia planum) and can be used to precisely constrain the mineral phases of calcium sulfate veins on Mars.

Keywords: Mars, Molecular spectroscopy, Planetary mineralogy
A Case Study of Interstellar Material Delivery: α Centauri. Interstellar material has been discovered in our solar system, yet its origins and details of its transport are unknown. Here, we present α Centauri as a case study of the delivery of interstellar material to our solar system. α Centauri is a mature triple star system that likely harbors planets, and is moving toward us with the point of the closest approach approximately 28,000 yr in the future. Assuming a current ejection model for the system, we find that such material can reach our solar system and may currently be present here. The material that does reach us is mostly a product of low (&lt;2 km s‑1) ejection velocities, and the rate at which it enters our solar system is expected to peak around the time of α Centauri's closest approach. If α Centauri ejects material at a rate comparable to our own solar system, we estimate the current number of α Centauri particles larger than 100 m in diameter within our Oort Cloud to be 106, and during α Centauri's closest approach, this will increase by an order of magnitude. However, the observable fraction of such objects remains low as there is only a probability of 10‑6 that one of them is within 10 au of the Sun. A small number (∼10) of meteors &gt;100 μm from α Centauri may currently be entering Earth's atmosphere every year: this number is very sensitive to the assumed ejected mass distribution, but the flux is expected to increase as α Centauri approaches.

Keywords: Meteor streams, Meteor radiants, Interstellar objects