Sazuna/UAT_keywords huggingface dataset:
Shaking and Tumbling: Short- and Long-timescale Mechanisms for Resurfacing of Near-Earth Asteroid Surfaces from Planetary Tides and Predictions for the 2029 Earth Encounter by (99942) Apophis. Spectral characterization of near-Earth asteroids (NEAs) has revealed a continuum of space-weathered states for the surfaces of S-complex NEAs, with Q-class NEAs, an S-complex subclass, most closely matching the unweathered surfaces of ordinary chondrite meteorites. Dynamical calculations of the orbital evolution of S-complex NEAs revealed that Q-class NEAs tend to have close encounters with terrestrial planets, suggesting that planetary tides may play a role in refreshing NEA surfaces. However, the exact physical mechanism(s) that drive resurfacing through tidal encounters and the encounter distance at which these mechanisms are effective have remained unclear. Through the lens of the upcoming (99942) Apophis encounter with Earth in 2029, we investigate the potential for surface mobilization through tidally driven seismic shaking over short timescales during the encounter and subsequent surface slope evolution over longer timescales driven by tumbling. We perform multiscale numerical modeling and find that the 2029 encounter will induce short-term tidally driven discrete seismic events that lead to high-frequency (&gt;0.1 Hz) surface accelerations that reach magnitudes similar to Apophis's gravity and that may be detectable by modern seismometers. It is still unclear if the shaking we model translates to widespread particle mobilization and/or lofting. We also find that there will be a significant change in Apophis's tumbling spin state that could lead to longer-term surface refreshing in response to tumbling-induced surface slope changes. We propose that through these mechanisms, space-weathered S-class asteroid surfaces may become refreshed through the exposure of unweathered underlying material. These results will be tested by the future exploration of Apophis by NASA'S OSIRIS-APEX.

Keywords: Near-Earth objects, Planetary surfaces, Asteroids, Gravitational interaction, Tidal interaction, Regolith, Asteroid surfaces
The Dehydration of Serpentines and Extraction of Water. Some groups of carbonaceous chondrites are dominated by phyllosilicates, specifically the serpentine group, which are characterized as alternating layers of silicates, metal cations, and hydroxyl (OH). Both antigorite, an Mg-rich member, and cronstedtite, an Fe-rich member, can be found in hydrated carbonaceous chondrites. Cronstedtite is found in substantial amounts in CM chondrites. The hydroxyl can make up to a quarter of the molecular mass, and part of it can turn into molecular water through thermal-induced crystal structure breakup. Understanding how the water is released through thermal effects is important for describing the history of certain near-Earth asteroids, as well as for ascertaining the viability of in situ resource utilization (ISRU) for a given object. Here we investigate the temperature of dehydration of the main serpentine constituents of carbonaceous chondrites—antigorite, lizardite, and cronstedtite—under both atmospheric and vacuum conditions. Our results show that the mass loss for cronstedtite starts at about 150 °C lower temperature than for the Mg serpentines. Additionally, vacuum does not affect significantly the onset of the mass loss, but it affects its dynamics. Finally, our observations suggest that cronstedtite loses additional oxygen molecules besides the ones contained within the hydroxyl. These results provide an important new perspective on the orbital history of certain asteroids and the required proximity to the Sun in order for them to lose water. Additionally, it puts the CM-type asteroids on the center stage for ISRU.

Keywords: Mineral physics, Carbonaceous chondrites, Meteorite composition, Asteroid surfaces
Telescope-to-Fireball Characterization of Earth Impactor 2022 WJ1. Comparing how an asteroid appears in space to its ablation behavior during atmospheric passage and finally to the properties of associated meteorites represents the ultimate probe of small near-Earth objects. We present observations from the Lowell Discovery Telescope and multiple meteor camera networks of 2022 WJ1, an Earth impactor that was disrupted over the North American Great Lakes on 2022 November 19. As far as we are aware, this is only the second time an Earth impactor has been specifically observed in multiple passbands prior to impact to characterize its composition. The orbits derived from telescopic observations submitted to the Minor Planet Center and ground-based meteor cameras result in impact trajectories that agree to within 40 m, but no meteorites have been found as of yet. The telescopic observations suggest a silicate-rich surface and thus a moderate-to-high albedo, which results in an estimated size for the object of just D = 40‑60 cm. Modeling the fragmentation of 2022 WJ1 during its fireball phase also suggests an approximate 0.5 m original size for the object as well as an ordinary chondrite-like strength. These two lines of evidence both support that 2022 WJ1 was likely an S-type chondritic object and the smallest asteroid compositionally characterized in space. We discuss how best to combine telescopic and meteor camera data sets, how well these techniques agree, and what can be learned from studies of ultrasmall asteroids.

Keywords: Impact phenomena, Asteroids, Meteors
Detection of Hydration on Nominally Anhydrous S-complex Main Belt Asteroids. We present the results of a survey of nominally anhydrous main belt S-complex asteroids. Thirty-three observations of 29 unique asteroids were obtained using the IRTF+SpeX instrument in prism and LXD short modes. We report for the first time that S-complex main belt asteroids have 3 μm features. The majority of the observations (27 of 33) have a detectable 3 μm feature that has at least 1% band depth or greater (within error), indicating the presence of hydration. Most of the asteroids have bands of 1%–2.5% depth, but a notable fraction (nine of the observations) have band depths of &gt;5%. These band depths are comparable to those of low albedo asteroids in the middle and outer belt that have experienced aqueous alteration. We investigate the origin of the hydration, searching for correlations with orbital, physical, and circumstantial parameters. However, we do not find any strong or moderate correlations with 3 μm band depth, indicating that multiple factors may be at play, including exogenic sources, primordial water, and/or solar wind implantation. Additionally, we report the mineralogies of the asteroids, derived from the prism observations.

Keywords: Infrared spectroscopy, Asteroids, Planetary science
Substantial Extension of the Lifetime of the Terrestrial Biosphere. Approximately one billion years (Gyr) in the future, as the Sun brightens, Earth's carbonate-silicate cycle is expected to drive CO2 below the minimum level required by vascular land plants, eliminating most macroscopic land life. Here, we couple global-mean models of temperature- and CO2-dependent plant productivity for C3 and C4 plants, silicate weathering, and climate to reexamine the time remaining for terrestrial plants. If weathering is weakly temperature dependent (as recent data suggest) and/or strongly CO2 dependent, we find that the interplay between climate, productivity, and weathering causes the future luminosity-driven CO2 decrease to slow and temporarily reverse, averting plant CO2 starvation. This dramatically lengthens plant survival from 1 Gyr up to ∼1.6–1.86 Gyr, until extreme temperatures halt photosynthesis, suggesting a revised kill mechanism for land plants and potential doubling of the future lifespan of Earth's land macrobiota. An increased future lifespan for the complex biosphere may imply that Earth life had to achieve a smaller number of "hard steps" (unlikely evolutionary transitions) to produce intelligent life than previously estimated. These results also suggest that complex photosynthetic land life on Earth and exoplanets may be able to persist until the onset of the moist greenhouse transition.

Keywords: Geological processes, Atmospheric evolution, Astrobiology, Habitable planets
Grain Size Effects on Visible and Near-infrared (0.35–2.5 μm) Laboratory Spectra of Rare Meteorite Classes. Linking near-Earth asteroids to associated meteorites can be a challenging process for many reasons, one being grain size differences. To address this issue for rarer meteorites, we studied visible and near-infrared (0.35–2.5 μm) reflectance spectra of 11 rare meteorite classes over five different grain size bins (45–90 μm, 90–150 μm, 150–300 μm, 300–500 μm, and 500–1000 μm). We analyzed the reflectance properties, diagnostic spectral band parameters (band centers and band area ratios), spectral slope, and taxonomic classification. The spectra were analyzed using principal component analysis to detect trends in principal component (PC) space and the impact on asteroid taxonomic classification in the Bus–DeMeo system. We found that the absolute reflectance (visual albedo) at 0.55 μm (photometric V band) typically decreases with increasing grain size, although there are some variations such as sharp increases for the slabs. Our EH4 and aubrite show a trend of increasing spectral slope with decreasing grain size. Our ureilite, angrite, winonaite, acapculoite, and mesosiderite show a general trend of a decrease in Band I (∼0.9 μm) depth with increasing grain size up to 500–1000 μm. Taxonomic classification of spectra of all grain sizes shows that classification tools generally struggle to differentiate grain size effects from mineralogical variations. This research demonstrates the need for a more robust taxonomic classification system that accounts for grain size and one that accurately classifies small near-Earth asteroids with regolith-free surfaces.

Keywords: Near-Earth objects, Chondrites, Infrared spectroscopy, Achondrites, Asteroids, Iron meteorites, Spectroscopy, Meteorites
Calibration and In-flight Performance of DART's Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO). The Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO) was the only instrument on board NASA's Double Asteroid Redirection Test spacecraft. DRACO had a 2628.326 mm focal length Ritchey–Chrétien telescope with a 208.28 mm aperture and a 0.29° field of view (FOV). The camera used a front-side-illuminated complementary metal–oxide–semiconductor (CMOS) sensor, BAE CIS2521F, with 2048 × 2048 illuminated pixels. DRACO worked with an onboard image processor to support autonomous targeting and ensure impact with Dimorphos, the secondary asteroid in the 65803 Didymos system, on 2022 September 26. This paper covers the calibration and in-flight performance of DRACO, including descriptions of ground and in-flight activities, instrument characterization, the calibration pipeline, and delivered Planetary Data System (PDS) products. DRACO exhibited low read noise and dark current that enhanced the instrument's sensitivity, although the sensor's nonlinearity and popcorn noise in global shutter mode required careful characterization and compensation to optimize terminal navigation performance. DRACO had a relatively circular point-spread function of less than two binned pixels across the full FOV. The combined calibration efforts achieved an absolute radiometric calibration (in both rolling and global shutter modes) of better than 20% and a relative calibration across an image of &lt;0.2%, despite no formal radiometric requirements. DRACO acquired 259,290 images in flight, which have been delivered to the PDS in both raw and calibrated forms. DRACO's excellent performance indicates that similar off-the-shelf CMOS detectors would be well suited for future planetary missions in low-radiation environments.

Keywords: Near-Earth objects, Space probes, Calibration, Astronomical instrumentation, Astronomy image processing
HyPyRameter: A Python Toolbox to Calculate Spectral Parameters from Hyperspectral Reflectance Data. Hyperspectral image cubes are information rich, typically containing hundreds of wavelengths and millions of spatial pixels. To condense this information into a more interpretable form, it is common to parameterize certain aspects of the spectra that are known to represent compositions of interest. Parameterizations of spectral features are called spectral parameters. Spectral parameters can be combined thematically into red, green, and blue (RGB) images, called browse products, to visualize compositional variation across a surface. Here, we present the Hyperspectral Parameter (HyPyRameter) toolbox: an open-source library, written in Python, to calculate spectral parameters for hyperspectral reflectance data. With the HyPyRameter toolbox, a user can calculate spectral parameters from point spectra or hyperspectral image cubes. Users can take advantage of the native parameters built into the HyPyRameter library, or easily customize the library of parameter formulas with built-in functions to suit the needs of a specific investigation. HyPyRameter can be run with Jupyter notebooks provided on the GitHub repo (https://github.com/Michael-S-Phillips/HyPyRameter). HyPyRameter is a flexible tool, installable via Anaconda (https://anaconda.org/michael--s--phillips/hypyrameter), with potential for wide-ranging applications to diverse fields including, but not limited to, planetary science, geology, agriculture, and mineral resource exploration.

Keywords: Surface composition, Spectroscopy
Zonal and Regional Jupiter Brightness Trends from the Hubble Outer Planet Atmospheres Legacy Program. The Hubble Outer Planet Atmospheres Legacy program began in 2014 and has observed Jupiter yearly from 2015 to 2024. Using high spatial resolution imaging from the Hubble Wide Field Camera 3, brightness trends were investigated focusing on the unique UV capability and absolute calibration consistency of the Hubble Space Telescope. From these data, a 4–5 yr period is observed at 24° north, particularly in the blue (F395N) and methane gas absorption (FQ889N) filters. Additionally, several wavelengths show a potential seasonal periodicity, especially at the equator, but more years of data are needed to confirm this trend over multiple Jupiter years. Variability in Oval BA and the Great Red Spot brightness is not cyclical, but these two anticyclonic features show changes on a yearly timescale.

Keywords: Planetary atmospheres, Jupiter, Atmospheric variability
Mercury Spectrophotometric Modeling Using MESSENGER Data. Mercury is covered by a regolith that affects how light is scattered from the planet's surface. To deduce the physical properties of Mercury's regolith, we use spectrophotometry from the Mercury Dual Imaging System instrument of NASA's MErcury Surface, Space ENvironment, GEochemistry and Ranging mission. The data come in eight colors in wavelengths of 433.2–996.2 nm, with phase angles of 20°–125°. A theoretical particulate-medium model is used to interpret the observed reflectance. The model includes a shadowing correction that depends on three geometry parameters of the regolith, allowing for the retrieval of the physical regolith structure from the spectrophotometry. The most important parameter is the packing density v, while the other two parameters describe the regolith's roughness as a fractional Brownian motion surface: the Hurst exponent H in the horizontal and the amplitude σ in the vertical direction. The numerical implementation of the model includes a set of discrete parameter values, which we extend by using trilinear interpolation: 0.15–0.55 for v, 0.20–0.80 for H, and 0.00–0.10 for σ. We optimize the model parameters in the least-squares sense using the Nelder–Mead simplex method followed by Markov Chain Monte Carlo (MCMC) sampling. Our results indicate that Mercury's regolith is densely packed (v = 0.547 ± 0.004) with moderate horizontal variations (H = 0.606 ± 0.009) and large height variations (σ = 0.0998 ± 0.0003). The MCMC solution allows us to predict the spectrophotometry for differing viewing geometries. Future work includes improving the implementation of the model by increasing the packing density values.

Keywords: Planetary surfaces, Solar system planets, Planetary science, Mercury (planet), Regolith
Thermophysical Diversity of Young Lunar Crater Ejecta Revealed with LRO Diviner Observations. Young (&lt;1 Ga) craters on the Moon are known to host diverse mixtures of ejecta with varying spectral and physical properties. In this work, we examine 13 yr of bolometric surface temperature data from the Diviner Lunar Radiometer on board the Lunar Reconnaissance Orbiter over the ejecta blankets of 10 lunar craters of varying sizes (D = 5–43 km) and ages (&lt;10 to ∼200 Ma) to study the spatial variation in their thermophysical characteristics. We find that a one-dimensional thermal model with two free parameters—the bottom-layer bulk density, ρ  d , and the transition height between the surface and bottom-layer densities, H—is able to accurately fit these data over our study regions, in contrast to previous models that assumed a constant ρ  d . Based on the best-fit model parameters, young crater ejecta can be divided into three classes: (1) "blocky" regions with a high abundance of boulders &gt;1 m in diameter, (2) "clastic" ejecta with varying levels of vertical density stratification, and (3) "impact melts" with high thermal inertia materials buried under a layer of less dense material. These thermophysically derived classes correlate strongly with observed morphology in high-resolution images and polarimetric signatures in decimeter-wavelength radar, and their thermophysical properties evolve distinctly with crater age. This technique represents the first time impact melt in many forms can be quantitatively distinguished by its physical properties from other types of ejecta using remote-sensing data and could have applications in validating models of impact ejecta production and deposition.

Keywords: Lunar craters, Lunar regolith, Infrared astronomy, Lunar impacts, Lunar surface, Remote sensing
New Candidates for Organic-rich Regions on Ceres. We explore the spatial distribution of organics on Ceres using the visible and near-infrared data collected by the Dawn mission. We employ a spectral mixture analysis (SMA) approach to map organic materials within the Ernutet crater at the highest available spatial resolution, thereby revealing a discontinuous, granular distribution and a possible association with an ancient crater on which Ernutet has been superimposed. The SMA technique also helps us identify 11 new areas as potential sites for organics. These regions are predominantly located within craters or along their walls, resembling the distribution pattern observed in Ernutet, which implies a possible geological link with materials exposed from beneath the surface. In one of these candidate regions situated in the Yalode quadrangle, we detected the characteristic 3.4 μm absorption band in the infrared spectrum, indicative of organics and carbonates. By combining the spatial resolution of the Framing Camera data with the spectral resolution of the Visual and Infrared Imaging Spectrometer using SMA, we investigated the distribution of the 3.4 μm band in this quadrangle. The absorption pattern correlates with the Yalode/Urvara smooth material unit, which formed after significant impacts on Ceres. The association of organic-rich materials with complex and multiple large-impact events supports an endogenous origin for the organics on Ceres.

Keywords: Ceres, Infrared spectroscopy, Complex organic molecules
Preservation of Microorganisms (Chroococcidiopsis sp. 029) in Salt Minerals under Low Atmospheric Pressure: Application to Life Detection on Mars. Salt minerals on Mars represent a promising target for investigating potential past surface and subsurface life. Terrestrial salt minerals have been shown to incorporate microorganisms within crystals. However, the effect of Mars's low atmospheric pressure on the preservation of microorganisms in salt minerals during their formation remains unclear. Here we investigated the interactions between microorganisms (Chroococcidiopsis sp. 029) and crystals of halite (NaCl), epsomite (MgSO4·7H2O), and gypsum (CaSO4·2H2O) during the rapid evaporation of brines under simulated Martian atmospheric pressure. Parallel experiments were conducted under terrestrial pressure for comparison. Halite, epsomite, and gypsum formed under both terrestrial and low-pressure conditions, though crystal morphologies varied depending on the pressure. Microorganisms were identified within fluid inclusions or as solid inclusions in the crystal matrix. Halite crystals exhibited a greater propensity to incorporate cells under low pressure compared to terrestrial pressure, while the entrapment of cells in epsomite was similar under both conditions. In contrast, significantly fewer cells were trapped in gypsum crystals under low pressure. The results demonstrate the feasibility of cell entrapment in salt minerals formed by rapid evaporation under low-pressure conditions on Mars, and atmospheric pressure exerts distinct influences on different types of salts. The variation in fluid inclusion size in halite under different pressures even shows promise as a possible paleobarometer. Our findings suggest that halite is the most promising candidate for preserving potential Martian life and could be an excellent target for future Mars sample return missions.

Keywords: Mars, Astrobiology
Characterization of the Dust and Sodium Tails of Comet C/2020 F3 (NEOWISE) from Parker Solar Probe and Amateur Observations. Comet C/2020 F3 (NEOWISE) reached perihelion on 2020 July 3 at 0.29 au and exhibited a highly structured dust tail. Using a simplified Finson–Probstein model, structures such as striae, observed in the tail in images obtained by the Parker Solar Probe spacecraft and amateur observers, are characterized in this work and parameterized in terms of dust ejection dates and dust β values. Other dust tail features are syndynic bands: bright, curved regions of the dust tail that lie within constant values of dust β. This study is the first in-depth analysis of these structures. Analysis revealed that the dust β distribution in the tail was approximately bimodal, corresponding to the two syndynic bands observed in the tail. The region between these bands, bounded by the β = 0.82 ± 0.02 and β = 1.20 ± 0.02 syndynes, appeared to have a reduced dust population, suggesting that dust grains of these β values were produced at a much lower rate. The alignments of the striae in the tail were measured and compared to the interleaved striae seen in C/2006 P1. C/2020 F3 was found to have no interleaved striae, which is possibly due to the timing of the comet's heliospheric current sheet crossing, not coinciding with, the main period of dust ejection.

Keywords: Comet tails, Long period comets, Comet dust tails, Comets, Comet origins