Sazuna/UAT_keywords huggingface dataset:
Mercury's Hidden Past: Revealing a Volatile-dominated Layer through Glacier-like Features and Chaotic Terrains. The discovery of global elemental volatile compositions, sublimation hollows, and chaotic terrains has significantly reshaped our understanding of Mercury's geology. These findings suggest the existence of volatile-rich layers (VRLs) extending several kilometers in depth, challenging the traditionally held view of a predominantly volatile-devoid Mercury crust. However, the precise nature and origin of these VRLs remain to be elucidated. The Raditladi basin exhibits morphologies analogous to terrestrial and Martian glaciers. These geomorphological features are potentially derived from impact-exposed VRLs, likely constituted of halite, other semivolatile salts, or organic volatiles. The distinctive rheological traits of substances such as halite substantiate this hypothesis. The inference posits a potential ubiquity of VRLs on a planetary scale, albeit potentially ensconced at considerable depth in specific regions. North polar chaotic terrains elucidate the VRLs' genesis and temporal evolution. The intense fragmentation of heavily cratered landscapes during their formation indicates a composition dominated by volatiles. This finding postulates a phase of volatile-enriched crustal accretion predating the Late Heavy Bombardment (~3.9 Ga). Regardless of lost mass, the unaltered basal elevation post-collapse signals a transition to a volatile-free stratum. The exposure of an exhumed lithological substrate within Mercury's stratigraphy, identifiable in gravimetry as an impacted paleosurface, contests the magma ocean differentiation concept for VRL formation. It infers a grand-scale construct originating from depositional processes, possibly due to the collapse of a transient, hot primordial atmosphere.

Keywords: Solar system terrestrial planets, Mercury (planet)
Pits on Jupiter-family Comets and the Age of Cometary Surfaces. Large and deep depressions, also known as pits, are observed at the surface of all Jupiter-family comets (JFCs) imaged by spacecraft missions. They offer the opportunity to glimpse the subsurface characteristics of comet nuclei and study the complex interplay between surface structures and cometary activity. This work investigates the evolution of pits at the surface of 81P/Wild 2, 9P/Tempel 1, and 103P/Hartley 2, in continuation of the work by Benseguane et al. on 67P/Churyumov-Gerasimenko. Pits are selected across the surface of each nucleus, and high-resolution shape models are used to compute the energy they receive. A thermal evolution model is applied to constrain how cometary activity sustained under current illumination conditions could modify them. Similar to what was found for 67P, we show that erosion resulting from water-driven activity is primarily controlled by seasonal patterns that are unique to each comet as a consequence of their shape and rotational properties. However, progressive erosion sustained after multiple perihelion passages is not able to carve any of the observed pits. Instead, cometary activity tends to erase sharp morphological features; they become wider and shallower over time. Our results reinforce the evolutionary sequence evidenced from independent measurables to transform "young" cometary surfaces, with sharp surface topography prone to outbursts, into "old" cometary surfaces. Finally, we suggest that the mechanism at the origin of the pits on JFCs should be able to carve these structures in a region of the solar system where water ice does not sublimate; the Centaur phase thus appears critical to understand JFC surface properties.

Keywords: Comet nuclei, Comet surfaces, Short period comets, Theoretical models
Material around the Centaur (2060) Chiron from the 2018 November 28 UT Stellar Occultation. A stellar occultation of Gaia DR3 2646598228351156352 by the Centaur (2060) Chiron was observed from the South African Astronomical Observatory on 2018 November 28 UT. Here we present a positive detection of material surrounding Chiron from the 74-inch telescope for this event. Additionally, a global atmosphere is ruled out at the tens of microbars level for several possible atmospheric compositions. There are multiple 3σ drops in the 74-inch light curve: three during immersion and two during emersion. Occulting material is located between 242 and 270 km from the center of the nucleus in the sky plane. Assuming the ring-plane orientation proposed for Chiron from the 2011 occultation, the flux drops are located at 352, 344, and 316 km (immersion) and 357 and 364 km (emersion) from the center, with normal optical depths of 0.26, 0.36, and 0.22 (immersion) and 0.26 and 0.18 (emersion) and equivalent widths between 0.7 and 1.3 km. This detection is similar to the previously proposed two-ring system and is located within the error bars of that ring-pole plane; however, the normal optical depths are less than half of the previous values, and three features are detected on immersion. These results suggest that the properties of the surrounding material have evolved between the 2011, 2018, and 2022 observations.

Keywords: Small Solar System bodies, Stellar occultation, Planetary rings, Centaur group
Investigating Diurnal and Seasonal Turbulence Variations of the Martian Atmosphere Using a Spectral Approach. We use a spectral approach to analyze the pressure and wind data from the InSight mission and investigate the diurnal and seasonal trends. Our analyses show that the daytime pressure and wind spectra have slopes of approximately -1.7 and -1.3 and, therefore, do not follow the Kolmogorov scaling (as was also previously reported for a reduced data set in Banfield et al.). We find that the nighttime pressure spectral slope is close to -1 (as reported in Temel et al.), and that the wind speed spectral slope is close to -0.5, flatter than the theoretical slope expected for the shear-dominated regime. We observe strong nocturnal (likely shear-generated) turbulent behavior starting around L s = 150° (InSight sol 440) that shifts to progressively earlier local times before reaching the "5th season" (InSight sols 530-710) identified by Chatain et al.. The diurnal spectral slope analyses indicate an asymmetry in the diurnal behavior of the Martian boundary layer, with a slow growth and fast collapse mechanism. Finally, the low-frequency (5-30 mHz) pressure data exhibit large spectral slope oscillations. These occur particularly during the periods with a highly stable atmosphere and, therefore, may be linked to gravity wave activity.

Keywords: Mars, Atmospheric dynamics
Spectroscopic Links among Giant Planet Irregular Satellites and Trojans. We collect near-infrared spectra (~0.75-2.55 μm) of four Jovian irregular satellites and visible spectra (~0.32-1.00 μm) of two Jovian irregular satellites, two Uranian irregular satellites, and four Neptune Trojans. We find close similarities between the observed Jovian irregular satellites and previously characterized Jovian Trojans. However, irregular satellites' unique collisional histories complicate comparisons to other groups. Laboratory study of CM and CI chondrites shows that grain size and regolith packing conditions strongly affect spectra of dark, carbonaceous materials. We hypothesize that different activity histories of these objects, which may have originally contained volatile ices that subsequently sublimated, could cause differences in regolith grain size or packing properties and therefore drive spectral variation. The Uranian satellites Sycorax and Caliban appear similar to TNOs. However, we detect a feature near 0.7 μm on Sycorax, suggesting the presence of hydrated materials. While the sample of Neptune Trojans have more neutral spectra than the Uranian satellites we observe, they remain consistent with the broad color distribution of the Kuiper Belt. We detect a possible feature near 0.65-0.70 μm on Neptune Trojan 2006 RJ103, suggesting that hydrated material may also be present in this population. Characterizing hydrated materials in the outer solar system may provide critical context regarding the origins of hydrated CI and CM chondrite meteorites. We discuss how the hydration state(s) of the irregular satellites constrains the thermal histories of the interiors of their parent bodies, which may have formed among the primordial Kuiper Belt.

Keywords: Centaur group, Asteroids, Infrared spectroscopy, Uranian satellites, Carbonaceous chondrites, Trojan asteroids, Spectroscopy, Trans-Neptunian objects, Irregular satellites, Neptune trojans, Jovian satellites
The Near-Earth Object Surveyor Mission. The Near-Earth Object (NEO) Surveyor mission is a NASA Observatory designed to discover and characterize asteroids and comets. The mission's primary objective is to find the majority of objects large enough to cause severe regional impact damage (&gt;140 m in effective spherical diameter) within its 5 yr baseline survey. Operating at the Sun-Earth L1 Lagrange point, the mission will survey to within 45° of the Sun in an effort to find objects in the most Earth-like orbits. The survey cadence is optimized to provide observational arcs long enough to distinguish near-Earth objects from more distant small bodies that cannot pose an impact hazard reliably. Over the course of its survey, NEO Surveyor will discover ~200,000-300,000 new NEOs down to sizes as small as ~10 m and thousands of comets, significantly improving our understanding of the probability of an Earth impact over the next century.

Keywords: Near-Earth objects, Sky surveys, Asteroids, Surveys, Infrared astronomy, Comets
Validation of the Survey Simulator Tool for the NEO Surveyor Mission Using NEOWISE Data. The Near-Earth Object Surveyor (NEO Surveyor) mission has a requirement to find two-thirds of the potentially hazardous asteroids larger than 140 m in size. In order to determine the mission's expected progress toward this goal during design and testing, as well as the actual progress during the survey, a simulation tool has been developed to act as a consistent and quantifiable yardstick. We test that the survey simulation software is correctly predicting on-sky positions and thermal infrared fluxes by using it to reproduce the published measurements of asteroids from the NEOWISE mission. We then extended this work to find previously unreported detections of known near-Earth asteroids in the NEOWISE data archive, a search that resulted in 21,661 recovery detections, including 1166 objects that had no previously reported NEOWISE observations. These efforts demonstrate the reliability of the NEO Surveyor Survey Simulator tool and the perennial value of searchable image and source catalog archives for extending our knowledge of the small bodies of the solar system.

Keywords: Surveys, Near-Earth objects, Asteroids
Geometric Properties of Water-ice Clouds as Observed from Jezero Crater in the First 600 sols with the NavCam Instrument On Board the Mars2020 Rover, Perseverance. In the first 600 sols of the Mars2020 mission, LS 5.6o - 316.8o, 46 cloud movies and 145 cloud surveys were collected to observe clouds at Jezero Crater, the landing site of the Perseverance Rover. Cloud movies were processed using the Mean-Frame Subtraction (MFS) method for revealing cloud structures, which were subsequently analyzed using digital-image processing. Two-dimensional Fast Fourier Transforms (2D-FFT) were used to compute cloud structure sizes ranging from 2.90 to 15.25 km for clouds between 30 and 50 km altitude, based on coincident Mars Climate Sounder vertical profiles of atmospheric water-ice. Same-value thresholding was used to detect the cloud structures in MFS-processed and projected cloud movies. The resolution dependence that was needed to resolve these structures over various thresholds was examined to find multifractal scaling of Mars clouds for resolutions between 0.1 and 1.6 km. We characterize the multiscaling observed in the images and its implications for the design of cloud-tracking cameras from the surface as well as for cloud-resolving models.

Keywords: Atmospheric clouds, Mars, Planetary atmospheres, Planetary science, Rovers
How Does the Thermal Environment Affect the Exosphere/Surface Interface at Mercury?. The fate of Mercury's exospheric volatiles and, in a lesser way, of the refractory particles absorbed in the first few centimeters of the surface both depend highly on the temperature profile with depth and its diurnal variation. In this paper, we review several mechanisms by which the surface temperature might control the surface/exosphere interface. The day/night cycle of the surface temperature and its orbital variation, the temperature in the permanent shadow regions, and the subsurface temperature profiles are key thermal properties that control the fate of the exospheric volatiles through the volatile ejection mechanisms, the thermal accommodation, and the subsurface diffusion. Such properties depend on the solar illumination from large to small scales but also on the regolith structure. The regolith is also space-weathered by the thermal forcing and by the thermal-mechanical processing. Its composition is changed by the thermal conditions. We conclude by discussing key characteristics that need to be investigated theoretically and/or in the laboratory: the dependency of the surface spectra with respect to temperature, the typical diffusion timescale of the volatile species, and the thermal dependency of their ejection mechanisms.

Keywords: Planetary surfaces, Exosphere, Space weather, Mercury (planet), Regolith
The NEO Surveyor Near-Earth Asteroid Known Object Model. The known near-Earth object (NEO) population consists of over 32,000 objects, with a yearly discovery rate of over 3000 NEOs per year. An essential component of the next generation of NEO surveys is an understanding of the population of known objects, including an accounting of the discovery rate per year as a function of size. Using a near-Earth asteroid (NEA) reference model developed for NASA's NEO Surveyor (NEOS) mission and a model of the major current and historical ground-based surveys, an estimate of the current NEA survey completeness as a function of size and absolute magnitude has been determined (termed the Known Object Model; KOM). This allows for understanding of the intersection of the known catalog of NEAs and the objects expected to be observed by NEOS. The current NEA population is found to be ~38% complete for objects larger than 140 m, consistent with estimates by Harris &amp; Chodas. NEOS is expected to catalog more than two-thirds of the NEAs larger than 140 m, resulting in ~76% of NEAs cataloged at the end of its 5 yr nominal survey, making significant progress toward the US Congressional mandate. The KOM estimates that ~77% of the currently cataloged objects will be detected by NEOS, with those not detected contributing ~9% to the final completeness at the end of its 5 yr mission. This model allows for placing the NEOS mission in the context of current surveys to more completely assess the progress toward the goal of cataloging the population of hazardous asteroids.

Keywords: Near-Earth objects, Astronomy data modeling, Sky surveys
Near-IR Spectral Observations of the Didymos System: Daily Evolution Before and After the DART Impact Indicates that Dimorphos Originated from Didymos. Ejecta from Dimorphos following the DART mission impact significantly increased the brightness of the Didymos-Dimorphos system, allowing us to examine subsurface material. We report daily near-IR spectroscopic observations of the Didymos system using NASA's IRTF that follow the evolution of the spectral signature of the ejecta cloud over 1 week, from 1 day before the impact. Overall, the spectral features remained fixed (S-type classification) while the ejecta dissipated, confirming that both Didymos and Dimorphos are constructed from the same silicate material. This novel result strongly supports binary asteroid formation models that include the breaking up of a single body due to rotational breakup of kilometer-wide bodies. At impact time +14 and +38 hr, the spectral slope decreased, but the following nights presented an increasing spectral slope that almost returned to the preimpact slope. However, the parameters of the 1 μm band remained fixed, and no "fresh"/Q-type-like spectrum was measured. We interpret this as follows. (1) The ejecta cloud is the main contributor (60%-70%) to the overall light during the ~40 hr after impact. (2) Coarser debris (≥100 μm) dominated the ejecta cloud, decreasing the spectral slope (after radiation pressure removed the fine grains ≤10 hr after impact). (3) After approximately 1 week, the ejecta cloud dispersed enough to make the fine grains on Didymos's surface the dominant part of the light, increasing the spectral slope to the preimpact level. (4) A negligible amount of nonweathered material was ejected from Dimorphos's subsurface, suggesting that Dimorphos was accumulated from weathered material ejected from Didymos's surface.

Keywords: Near-Earth objects, Asteroids, Infrared spectroscopy, Asteroid satellites, Asteroid surfaces
Synthetic Detections of Interstellar Objects with the Rubin Observatory Legacy Survey of Space and Time. The discovery of two interstellar objects passing through the solar system, 1I/'Oumuamua and 2I/Borisov, implies that a galactic population exists with a spatial number density of order ~0.1 au-3. The forthcoming Rubin Observatory Legacy Survey of Space and Time (LSST) has been predicted to detect more asteroidal interstellar objects like 1I/'Oumuamua. We apply recently developed methods to simulate a suite of galactic populations of interstellar objects with a range of assumed kinematics, albedos, and size-frequency distributions (SFDs). We incorporate these populations into the objectsInField algorithm, which simulates detections of moving objects by an arbitrary survey. We find that the LSST should detect between ~0 and 70 asteroidal interstellar objects every year (assuming the implied number density), with sensitive dependence on the SFD slope and characteristic albedo of the host population. The apparent rate of motion on the sky-along with the associated trailing loss-appears to be the largest barrier to detecting interstellar objects. Specifically, a relatively large number of synthetic objects would be detectable by the LSST if not for their rapid sky motion (&gt;0.°5 day-1). Therefore, algorithms that could successfully link and detect rapidly moving objects would significantly increase the number of interstellar object discoveries with the LSST (and in general). The mean diameter of detectable, inactive interstellar objects ranges from ~50 to 600 m and depends sensitively on the SFD slope and albedo.

Keywords: Interstellar objects
Characterization of the DART Impact Ejecta Plume on Dimorphos from LICIACube Observations. We modeled the geometry and the three-dimensional orientation of the ejecta cone triggered by the impact of the DART spacecraft on the asteroid Dimorphos. We used eight LUKE images of the impact acquired by the CubeSat LICIACube that flew by the Didymos system shortly after the impact. These images, which show the ejecta cone in both face-on and side-on profiles, enabled us to reconstruct the ejecta cone in inertial space. We started our model as a simple cone with a circular base and developed it to a rotated cone with an elliptical base that best fit the data. The cone axis points to R.A., decl. (in J2000): ${147}_{-10^\circ }^{+1^\circ }$ , + ${16}_{-6^\circ }^{+4^\circ }$ . The cone is characterized by two perpendicular half-angles of $\eta ={69}_{-3^\circ }^{+1^\circ },\gamma ={51}_{-11^\circ }^{+1^\circ }$ and a rotation of ω = 12° around its axis. The apex of the cone is located near the center of Dimorphos within 15 m. The intersection of the cone and the surface of Dimorphos (surface enclosed by the cone) would correspond to a crater with a maximum radius of about 65 m. The characterization of the cone axis is directly related to the computation of the momentum enhancement factor (β) of the impact, and it hence proves the crucial need of studying impacts in the context of planetary defence scenarios. The results of this work could potentially be used to constrain whether the impact took place in a strength-dominated or a gravity-dominated regime. This work shows the important scientific return of the LICIACube CubeSat in the context of planetary defence.

Keywords: Asteroids
Visible and Near-infrared Spectral Properties of Martian Slope Streaks. Martian slope streaks are large surface features with lower albedo than their surroundings that are one of the few active geologic processes occurring on Mars today. We investigated the slope streaks' spectral properties using images from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at nine sites, including three sites with observations over multiple years to enable time-series analysis. For each individual slope streak within each image, we determined the average spectra of each streak and of the slope immediately adjacent to account for changes in geology across a CRISM image or within slopes containing streaks. We find a trend where the visible spectral continuum (0.4-0.6 μm) is strongly negative for the darkest slope streaks, and the spectral continuum increases as the slope streaks fade, consistent across all sites and over multiple observations of the same site. We do not find absorption at 1.4 or 1.9 μm associated with hydration. In some slope streaks, we see evidence of Fe-bearing minerals, but these signatures are also found in the streak-free slope directly adjacent, suggesting that the streaks have a similar mineralogy to their surroundings. The spectral changes that we see are most consistent with changes in the fine dust component and support a dry flow mechanism whereby slope streaks are formed by processes that trigger dust removal from the slope in particular locations, with the streaks slowly fading as dust resettles on the surface.

Keywords: Surface processes, Mars, Infrared spectroscopy, Remote sensing
Impact Crater Databases for Pluto and Charon, Version 2. Pluto and Charon are the farthest bodies from the Sun that have been visited by spacecraft where more than several dozen impact craters can be accurately identified and measured. These craters form a critical record of outer solar system impactors in the trans-Neptunian environment, so an accurate census of them is important for numerous dynamical applications seeking to understand the Kuiper Belt and its evolution. In 2017, a crater database was published based on several different researchers mapping on various image products from the New Horizons mission. To date, that remains the only work that has tried to provide a complete census of the craters on Pluto and Charon. Meanwhile, Singer et al. mapped on different, more final image products, while Robbins &amp; Singer worked to reconcile their crater populations, demonstrate general agreement, and lay out issues with the previous work from 2017. However, neither attempted to make complete databases of Pluto's or Charon's craters. To come full circle, we present a short report on a revised crater database for both Pluto and Charon that incorporates revised interpretations of geologic features on both bodies; this work supersedes our other Pluto and Charon crater database work.

Keywords: Plutonian satellites, Craters, Pluto