Sazuna/UAT_keywords huggingface dataset:
Highly Heterogeneous Parent Body of the Rare Andesitic Erg Chech 002 Meteorite Revealed by the Revisited Mn–Cr Isotopic Systematics. Erg Chech 002 (EC 002), an andesitic meteorite, has been dated to be the oldest magmatic rock in the solar system. However, controversy has arisen due to inconsistent dating results and isotopic compositions in previous studies, which complicates understanding the evolution of andesitic magmatism in the early solar system. In this study, we conducted comprehensive Cr isotopic studies on two fragments of EC 002, identifying distinct nominal crystallization ages (4567.3 ± 0.8 and 4565.9 ± 0.6 Ma, respectively), as well as nucleosynthetic 54Cr anomalies (ɛ54Cr values of ‑1.12 ± 0.16 and ‑0.57 ± 0.16, respectively) and ɛ53Cr values (‑0.37 ± 0.06 and ‑0.06 ± 0.06, respectively). These results highlight the highly isotopically heterogeneous nature of the EC 002 meteorite. The difference in nominal crystallization ages likely reflects the initial 53Mn/55Mn heterogeneity among various EC 002 fragments. The highly isotopically heterogeneous nature of the EC 002 meteorite may be directly inherited from its surrounding nebula, suggesting subplanetesimal-scale heterogeneity of the inner solar nebula during the formation time of EC 002. We affirmed the oldest crystallization age for EC 002 among all achondrites at ∼4565.9 Ma. Previous discrepancies in dating results and isotopic compositions should arise from the isotopic heterogeneity in the EC 002 meteorite.

Keywords: Cosmochronology, Cosmochemistry, Planet formation, Planetesimals
Sea Surface and Hydrological Activity Observed in Titan's Punga Mare. We present new evidence for active coastal and oceanic features in Titan's Punga Mare observed in a high-phase Cassini Visual Infrared and Mapping Spectrometer observation of sun glint from the T110 flyby. We observe sunglint in a coastal channel, Apanohuaya Flumen, resulting from differing pixel contributions of land adjacent to the liquid-filled channel. Along the eastern shoreline, we identify a 5 μm bright margin. A possible explanation for this brightening includes a coastal margin of capillary wave fields. We find additional evidence of variegated sea surface roughness in Fundy Sinus and isolated Sun glitter near Hawaiki Insulae. RADAR observations of debouches (where rivers meet bays) within Punga Mare overlap several bright 5 μm pixels that indicate rough liquid surfaces. We postulate that a change in liquid flow regimes, possibly occurring as surface streamflow or bubble outburst events, may be responsible for surface roughness near these debouches. These observations imply air–sea–land interactions and active hydrology represented by possible streamflow are present in Titan's sea district during the northern summer.

Keywords: Ocean-atmosphere interactions, Titan
Discovery of Extraterrestrial <SUP>244</SUP>Pu in 2 Million Year Old Fossilized Stromatolites. The rapid neutron capture process (r-process) is responsible for producing about half of the elements heavier than iron in the Universe through cataclysmic events such as core-collapse supernovae and neutron star mergers (NSMs). Despite extensive research, the exact astrophysical sites of the r-process remain one of the unanswered questions in science. The well-known supernova-produced radioisotope 60Fe has been detected in terrestrial reservoirs, providing evidence that material from a nearby supernova reached Earth approximately 2 million years (Ma) ago. Our study reports the detection of 244Pu in fossilized stromatolite samples that are 2.0 Ma old, collected from palustrine–lacustrine stratigraphic layers dating back to approximately 5 Ma located at the margins of the present-day Lake Turkana Basin in northern Kenya. We demonstrate that stromatolites can mass-concentrate actinides in the range of 102–103. Using accelerator mass spectrometry, we isolate 244Pu and eliminate the anthropogenic contribution. From our findings, we evaluate a terrestrial fluence between 0.2 and 4.7 × 103 at cm‑2, in relative agreement with previous studies. The detection of the r-process 244Pu around 2 Ma ago raises the possibility of a common supernova origin with 60Fe; however, alternative scenarios, such as the production of 244Pu in NSMs or other cosmic events and its transport to Earth alongside 60Fe via interstellar debris, cannot be ruled out, highlighting the need to consider multiple mechanisms for isotopic transport in the cosmos.

Keywords: R-process, Mass spectrometry
Identifying the Dimensions of Degraded Impact Structures Using Digital Elevation Models: A Proof of Concept for Silicate Planets. Determining the physical dimensions of hypervelocity impact structures is challenging due to erosion of their primary relief features on Earth. Critical measurements, such as outer rim diameter, are important for estimating the kinetic energy released and subsequent environmental effects. We developed a Radial Profile Analysis System algorithm, which uses a digital elevation model (DEM) to identify topographic rings surrounding a complex impact structure through an iterative process that assigns the most consistently identified positive relief ring as the apparent outer rim. We investigated five terrestrial impact structures across a range of apparent diameters whose physical dimensions are well established from geological or geophysical studies. Multiple DEM data sets from 2 to 30 m horizontal resolution were evaluated to determine the role of spatial resolution in estimating apparent outer rim diameters. The most reliable predictions were achieved using the 12 m TanDEM-X data set with an estimated error ≤16%. We then achieved an estimated error ≤8% when applying the algorithm to three Martian peak ring impact structures (Kepler, Lowell, and Lyot) using 200 m resolution DEMs, and 1%–13% when applied to a 600 m resolution DEM of the Mead multi-ringed impact structure on Venus. Our results indicated that apparent outer rim diameters of complex impact structures can be estimated using these methods with reasonable reliability, but prediction efficacy decreased with decreasing DEM vertical fidelity. Application of these methods to additional impact structures is required to quantify prediction uncertainty before applying this methodology to more recent impact structures with questionable diameters.

Keywords: Craters
The New Titan Planetary Climate Model. I. Seasonal Variations of the Thermal Structure and Circulation in the Stratosphere. Observations of Titan through Cassini's mission allowed Saturn's moon's stratospheric thermal structure and composition to be mapped over half a Titan year. Seasonal variations revealed various unexplained phenomena, such as mechanisms within the polar vortex, thermal structure evolution at high latitudes, and the impact of the enrichment in trace compounds during winter polar nights. We have developed the Titan Planetary Climate Model (Titan PCM)—an improved version of the IPSL Titan Global Climate Model (GCM)—including upgraded radiative transfer, now based on a flexible correlated-k method, updated spectroscopic data on gases, and integration of a new microphysics model for haze and clouds. Our photochemical solver extends computation of the composition above the top of the model up to 1300 km. The radiative transfer is now coupled with microphysics, consisting of the first full radiative coupling of microphysics within a Titan GCM. The model is presented along with its dynamics, thermal structure, and seasonal variations. Despite biases above 10 Pa due to upper boundary limitations, the Titan PCM leads to better modeling of the temperature profiles in the middle atmosphere. Consequently, it is now possible to address some scientific issues about thermal structure in polar regions. Investigations into fall and winter polar phenomena, particularly focusing on thermal structure control and equinoctial circulation reversal, were conducted. This study is linked to the radiative destabilization of the lower polar stratosphere, observed at the end of winter by Cassini radio-occultations. The results confirm a dynamic interplay between haze and gas distributions, which influence the thermal structure.

Keywords: Planetary polar regions, Planetary atmospheres, Titan, Radiative transfer, Planetary climates
The New Titan Planetary Climate Model. II. Titan's Haze and Cloud Cycles. Observations of Titan have long revealed the presence of seasonal cycles, including haze, clouds, and gases. The lack of information on the different processes that govern these cycles prevents us from understanding all the phenomena taking place in Titan's atmosphere. In this work, we survey Titan's cycles exhaustively to understand their mechanisms, in particular the haze and cloud cycles that govern a large part of Titan's climate and its surface. The Titan Planetary Climate Model (Titan PCM)—an upgraded version of the IPSL Titan Global Climate Model—incorporates a microphysical model for haze and clouds, along with a methane cycle (evaporation, transportation, condensation, precipitation). The model also features improved radiative transfer and updated spectroscopic data on gases. The Titan PCM includes phenomena hitherto omitted from Titan 3D simulations, such as cloud nucleation and condensation. Furthermore, we have coupled microphysics with radiative transfer in order to take account of feedback from haze and clouds on the thermal structure. We find that the haze follows a seasonal cycle constrained by the pole-to-pole circulation in the stratosphere. Below, the cold regions between 30 and 90 km trigger the condensation of minor species, forming a condensate mist layer throughout the year. Methane clouds form near the surface (5–25 km), in the ascending branches of the circulation, while polar clouds form higher up (60–300 km) at the winter pole after enrichment in trace compounds. The Titan PCM now enables detailed exploration of the long-term variations in Titan's cycles, providing insights for future observations.

Keywords: Methane, Atmospheric clouds, Planetary atmospheres, Titan, Planetary climates
NEOWISE Data Processing and Color Corrections for Near-Earth Asteroid Observations. The Wide-field Infrared Survey Explorer and NEOWISE missions are a key source of thermal data for near-Earth asteroids (NEAs). These missions, which utilized a space-based platform in Earth orbit, produced thermal images across four different wavelength bands, W1 – W4, with effective wavelengths of 3.4, 4.6, 12, and 22 μm respectively. Despite its use for NEA observations though, the mission architecture was originally designed to observe stars. Thus, careful data analysis methods are crucial when working with NEA data to account for the differences between these objects. However, detailed information on how to work with these data can be difficult to find for users unfamiliar with the mission. The required information is well documented, but locating it can be challenging, and many details, such as specifics about color corrections, are not fully explained. Therefore, in this work, we provide a set of "lessons learned" for working with NEOWISE data, outline the basics of how to retrieve and process NEOWISE data for NEA investigations, and present an empirical method for color correction determination. We highlight the importance of this process by processing data for three NEAs, finding that nearly half of all available observations should be discarded. Finally, we present simple thermal model results based on different levels of data analysis to highlight how data processing can affect model results.

Keywords: Infrared astronomy, Near-Earth objects, Infrared telescopes
The 2014–2015 Holuhraun Lava Flow-field in Iceland as a Planetary Analog for Young Volcanic Terrains in Elysium Planitia, Mars. Elysium Planitia is the youngest volcanic terrain on Mars, and the only region that exhibits evidence of ongoing magmatic activity today. This makes Elysium Planitia crucial for understanding the tectonic, magmatic, volcanic, and thermal state of the planet. The 2014–2015 Holuhraun eruption in the Icelandic Highland provides a unique opportunity to study a large-volume, fissure-fed eruption—with associated lava–water interactions—that serves as a terrestrial analog for volcanic terrains in Elysium Planitia. Here, we detail the key similarities between the Holuhraun and Elysium Planitia sites, including their geological settings, prominent lava morphologies, and implications for inferring eruption dynamics. Even in the absence of global plate tectonics on Mars, both locations exhibit young fissure systems, indicating an extensional tectonic setting. Detailed investigations of lava morphologies offer valuable insights into the dynamics and evolution of fissure-fed eruptions. Of particular importance are "transitional" lavas, which, at the Holuhraun site, are associated with different effusion rates and eruption stages. The presence of inflation features with disrupted surfaces in Elysium Planitia supports the interpretation that these are rubbly lava flows formed in association with high local strain rates, implying an initial high effusion rate. However, both locations exhibit polygonal terrain, which is indicative of low strain rate conditions, implying a change to cooling under broadly stagnant conditions. Due to its variety of recent geologic processes, including volcanic and potentially aqueous flows, the presence of pristine surfaces, as well as associated tectonic and magmatic activity, Elysium Planitia is a compelling target for future exploration.

Keywords: Surface processes, Mars, Geological processes, Planetary geology, Volcanism
Reprocessing the NEAT Data Set: Preliminary Results. We have created a new image analysis pipeline to reprocess images taken by the Near Earth Asteroid Tracking survey and have applied it to 10 nights of observations. This work is the first large-scale reprocessing of images from an asteroid discovery survey in which thousands of archived images are recalibrated and searched for minor planets, and the resulting observations are reported to the Minor Planet Center. We describe the software used to extract, calibrate, and clean sources from the images, including specific techniques that accommodate the unique features of these archival images. This pipeline is able to find fainter asteroids than the original pipeline.

Keywords: Near-Earth objects, Sky surveys, Astronomy software, Astrometry, Photometry
Large-scale Roughness Properties of the Lunar North and South Polar Regions as Measured by the Lunar Orbiter Laser Altimeter (LOLA). The lunar polar regions are high-priority targets for scientific investigation and exploration. To aid these endeavors, we produced enhanced altimetry data from the Lunar Orbiter Laser Altimeter for the north polar region, from which we computed new maps of surface height and slope as well as topographic roughness on horizontal baselines of 100–1600 m. We also produced a new map of permanently shadowed regions (PSRs) that contains fewer artifacts and is higher resolution than previous maps. These new maps were then compared to an analogous set previously produced for the south polar region. Generally, in both polar regions, more steeply sloped terrain is rougher at baselines ≲200 m and has a bluer roughness spectrum, a behavior hypothesized to be due to downslope mass transport. Roughness in the polar regions is also correlated with regolith temperature, and we discuss several possible causes including surface ice in unresolved cold traps, subsurface ice outside cold traps, and changes in the regolith's geotechnical properties. In the north, there are more PSRs with areas ∼0.1–1.0 km2 and fewer with areas &gt;100 km2, which may be due to the north having a higher number of craters with diameters of hundreds of meters to ∼3 km. The new maps presented here have many applications in the scientific study and exploration of the lunar north polar region, such as geologic mapping, modeling of cold traps, landing-site characterization, traverse planning, and the interpretation of in situ and remote-sensing data.

Keywords: Lunar highlands, Lunar surface, Lunar features, Lunar regolith
Hot Spot Detections and Volcanic Changes on Io during the Juno Epoch: Orbits PJ5 to PJ55. We report volcanic changes on Io since the last Galileo (2002) and New Horizons (2007) flybys as observed by NASA's Juno spacecraft, examining Io's volcanism down to the local scale (&lt;10 km pixel‑1). From 3428 Jovian Infrared Auroral Mapper image frames obtained between 2017 March 21 (PJ5) and 2023 October 15 (PJ55), a catalog of 2305 hot spot detections with temperatures &gt;200 K at 325 individual sites of volcanic activity has been generated. Where possible, hot spot color temperature, emitting area, and power output are calculated. Some prominent areas of volcanic activity first identified or better resolved in Juno data (Tonatiuh, Lei-Kung Fluctus, Volund, Guaraci Fluctus, Seth Patera, and others) are described. We examined their appearance, volcanological and geological settings, observed thermal emission, and evolving behavior, and quantified the changes that have taken place. Volcanic activity at Tonatiuh and Guaraci Fluctus, the sites of newly imaged lava flows, are examined in detail. At Tonatiuh, JunoCam data provide important context; at Guaraci Fluctus, the combination of data from multiple assets yields a comprehensive understanding of the evolution of a specific eruption episode. We further examine different types of active paterae, some possibly containing lava lakes. A group of bright eruptions are identified whose spatial and temporal locations suggest regional clustering. Our estimates of volcanic thermal emission are broadly consistent with previous analyses of spacecraft data. All derived products are available from the Io Geographical Information System database at Arizona State University. Appendix A contains newly approved feature names.

Keywords: Io, Galilean satellites, Volcanism
Gauss-Radau Small-body Simulator (GRSS): An Open-source Library for Planetary Defense. We present GRSS, a small-body propagation and orbit determination library specifically designed for planetary defense applications. GRSS is an end-to-end, open-source software tool that begins with optical observations obtained from the Minor Planet Center and Gaia spacecraft, as well as radar observations from the Jet Propulsion Laboratory, and ends with reliable predictions about the trajectory of a small body in the solar system. The library is built on a C++11 orbit propagation core and provides additional orbit determination capability through a Python interface for ease of use. We conducted extensive validation for both of these components of the library by comparing them with the state-of-the-art operational software tools. We demonstrate the capabilities of GRSS by applying it to orbit propagation for (65803) Didymos and orbit determination for (29075) 1950 DA. We also used GRSS to calculate the keyholes for the 2135 close encounter of (101955) Bennu and determine the impact location for 2024 BX1 and 2024 RW1. The library is designed to be modular and extensible, allowing for future addition of additional orbit filters and dynamical models. GRSS is publicly available on GitHub under a GPLv3 license and is intended to be a community resource for planetary science and planetary defense.

Keywords: Celestial mechanics, Comet dynamics, Orbit determination, Asteroid dynamics
The Viability of Glycine Fermentation in Titan's Subsurface Ocean. Energy and nutrient sources for life could be delivered to Titan's subsurface water ocean from both its surface above and its core below. Organic matter forming de novo in Titan's atmosphere and depositing on the surface may hydrolyze upon descent into the ocean with impact-generated melt pools sinking through the ice, adding to a primordial inventory released by the core during differentiation and/or across geologic time. This raises the possibility that abiotic organic carbon could fuel heterotrophic carbon assimilation into biomass in Titan's ocean if it is inhabited. Glycine fermentation is one possible metabolism of interest, because mechanisms exist to transport glycine to Titan's ocean and anaerobic fermentations do not rely on additional strong oxidants which may not be present on Titan. Using bioenergetic modeling, we show that while conditions favorable to glycine fermentation may exist, they are highly dependent on temperature. Additionally, the ability of that metabolism to fuel a global biosphere is limited by the slow delivery of glycine by impact melt pools (&lt;10 nmolal yr−1 optimistically, with a &gt;1 mmolal primordial component). A total population of 1014─1017 cells (a few kilograms of carbon) can be sustained, amounting to less than 1 cell kg─1 water when diluted through the entire ocean. Constraining notionally detectable biospheres on Titan will therefore require (i) considering localized environments that may concentrate cells, (ii) better characterizing other candidate metabolisms (e.g., degradation of acetylene or polyaromatic hydrocarbons) for quantitative bioenergetic modeling, and (iii) resolving new mechanisms to deliver organics and oxidants for life.

Keywords: Astrobiology, Titan
Earth as an Exoplanet: Investigating the Effects of Cloud Variability on the Direct-imaging of Atmospheres. A planet's spectrum is dynamic and only represents a time-dependent snapshot of its properties. Changing atmospheric conditions due to climate and weather patterns, particularly variation in cloud cover, can significantly affect the spectrum in ways that complicate the understanding of a planet's baseline atmospheric properties. Variable cloud cover and cloud properties affect the detectability of atmospheric constituents, and also greatly influence the radiative transfer that determines a planet's spectrum. This has considerable implications for direct-imaging observations of potentially habitable exoplanets, and thus, it is critical to study and characterize the effects of clouds on their spectra. Clouds have been extensively modeled before, and their effects have been incorporated across climate frameworks spanning a spectrum of complexity. Given the challenges associated with modeling clouds, we adopt a novel approach in this work to study the effects of clouds by using real-time cloud data from Earth observations. Treating Earth as an exoplanet and using detailed observations from the MERRA-2 data collection, we quantify the effects of cloud variability on the spectrum as well as on the detectability of atmospheric constituents, specifically biomarkers like O2, O3, and H2O. The coverage and vertical position of clouds significantly affect the signal-to-noise ratios of these gases and subsequently their detectability in exo-Earth atmospheres. Moreover, we show that variations in the amount of cloud cover will potentially confound efforts to retrieve a stable baseline atmosphere for a planet. This work has important applications to future direct-imaging missions like the Habitable Worlds Observatory.

Keywords: Biosignatures, Exoplanet atmospheres, Direct imaging, Atmospheric clouds