Sazuna/UAT_keywords huggingface dataset:
Mineralogy and Geochemistry of Xenoliths and Phreatomagmatic Deposits in Potrillo Volcanic Field, New Mexico, Determined from Portable Instruments: Applications to Surface Exploration of the Moon and Mars. Instruments that yield information about the mineralogy and chemistry of surface materials will be part of future robotic and human exploration of the Moon and Mars. Accurate interpretation of such data can be informed by coordinated analyses of relevant materials in terrestrial analog terrains. We used a suite of portable instrumentation—visible-to-shortwave infrared (VSWIR) spectroscopy, thermal infrared (TIR) spectroscopy, and X-ray fluorescence—to conduct coordinated mineralogical, geochemical, and visual characterization of a suite of outcrops and loose rocks in Kilbourne Hole and Hunts Hole, New Mexico. A variety of textures, particle sizes, and petrogenetic origins were examined. Data were interpreted using spectral models, spectral library comparisons, and chemical calibration curves and compared to mineralogical information derived from X-ray diffraction. Insights and limitations for each technique are presented in terms of surface type; for example, both the VSWIR and TIR instruments exhibited limitations in discerning the full mineralogy of the fine-grained tuff beds. The diverse suite of xenoliths was apparent in TIR spectral images, and the dominant mineral component was identifiable through linear unmixing of TIR spectra. However, inaccuracies in mineral abundance were also observed, highlighting the need for use of more advanced analysis methods. Known lithological diversity was less apparent in VSWIR spectra, which were dominated by minor amounts of phyllosilicates within or coating the rocks. Finally, based on the dearth of mafic minerals and the abundance of quartz, we infer that the Kilbourne/Hunts tuff beds are dominated by fragments of country rock ("accidentals") rather than juvenile magmatic materials.

Keywords: Space vehicle instruments, Infrared spectroscopy, Mars, Surface composition, Lunar surface
VIPER Site Analysis. We needed to evaluate available orbital data of NASA's Volatiles Investigating Polar Exploration Rover (VIPER) mission area in order to derive a variety of maps to help the science team identify scientifically interesting places for the rover to visit and to provide scientific context for our mission. Some of these maps also fulfilled engineering and mission design needs to enable safe and efficient landing and roving. We incorporated data from the Lunar Reconnaissance Orbiter Camera, the Lunar Orbital Laser Altimeter, the Mini-RF instrument, the Chandrayaan-2 Orbital High Resolution Camera, the Korean Pathfinder Lunar Orbiter's Shadowcam, the Kaguya Spectral Profiler and Multiband Imager, and the Chandrayaan-1 Moon Mineralogy Mapper. We used a variety of techniques to build these maps, including stereogrammetry, shape-from-shading, ice stability depth and surface temperature calculations, and the horizon method for solar illumination and direct-to-Earth communications maps. Altogether, these maps allowed us to survey for boulders, evaluate features in permanently shadowed regions that VIPER might explore, provide mineralogic context for what VIPER's instruments may learn, estimate the ages and radar properties of craters in the VIPER mission area, and evaluate the potential for gravity traverses with the rover. These data and techniques provided a rich set of information from which both the VIPER science team and engineering teams were able to draw in order to plan a safe landing and to plan a VIPER surface mission that will be both scientifically valuable and robust from an operational perspective.

Keywords: Space vehicle instruments, Remote sensing, The Moon, Surface processes
Spectrophotometry of Selected Regions of Europa—Revisiting Galileo NIMS Data. Europa's surface is one of the most compelling mysteries of the solar system. It displays complex photometric behavior driven by its rich geology and interaction with the Jovian environment. Cryovolcanism across the surface creates frequent resurfacing, which is competing with external plasma and meteorite bombardment. This study revisits data from Galileo's Near-Infrared Mapping Spectrometer to conduct a comprehensive, multiwavelength photometric analysis of selected regions across Europa's surface. Using a Bayesian inversion framework and the Hapke photometric model, we estimate key surface parameters—including single scattering albedo, macroscopic roughness, and phase function properties—across three geologically diverse regions. Results show a significant link between macroscopic roughness and single scattering albedo, where values of  θ¯  will sharply change when the single scattering albedo becomes too high (in this study, we found this transition to happen at ω ≈ 0.8). This is caused by multiple scattering that becomes too significant at a certain brightness and results in the illumination of shadows. This effect is potentially leading to systematic underestimation of roughness in traditional photometric modeling focused on the visible wavelengths. In addition, we observe increasing forward scattering at longer wavelengths, suggesting changes in internal scattering properties or composition. These findings highlight the need to account for albedo-driven photometric behavior in future analyses. This work is important to inform planetary data analysis in general but particularly for the planning of remote-sensing observations of the upcoming missions bound to the Jovian system—NASA's Europa Clipper and ESA's JUICE.

Keywords: Bayesian statistics, Surface photometry, Radiative transfer, Photometry, Spectrophotometry
The Near-infrared Spectral Characteristics of Water Ice, Epsomite, and Halite Mixtures Relevant to Europa. We publish the first near-infrared spectra of grain particulate mixtures of water ice, epsomite, and halite at cryogenic temperatures. Furthermore, we perform a quantitative assessment of the ability of both intimately and linearly mixed models to reproduce laboratory data of different grain mixtures of water ice, as well as water ice mixed with epsomite. We find that smaller grains of water ice impart a stronger influence than larger grains of water ice on the 2.0 μm spectral feature in epsomite, and grain size signatures for both halite and epsomite are challenging to discern for larger grain sizes as a result of the saturated absorption features. These findings may indicate that an observation bias toward smaller grain sizes of ice could exist, and that quantitative assessments provided by spectral mixture analyses will be the most reliable method for determining compositions and abundances of materials. We also find that the linearly mixed and intimately mixed models of water ice appear to match the laboratory spectra as expected, though they still display some inconsistencies, often either in the continuum or the absorption features. When modeling pure water ice and water ice mixed with epsomite, no discernible difference is observed between the fits of the linearly and intimately mixed models. Future spectral mixture analyses that use epsomite should be aware of a potential error in the published epsomite optical constant data, in which the cryogenic data appear to be taken at ambient conditions.

Keywords: Infrared spectroscopy, Natural satellite surfaces, Ice spectroscopy, Europa, Galilean satellites
Multiple Giant Impacts and Chemical Equilibria: An Integrated Approach to Rocky Planet Formation. During the formation of rocky planets, the surface environments of growing protoplanets were dramatically different from those of present-day planets. The release of gravitational energy during accretion would have maintained a molten surface layer, forming a magma ocean. Simultaneously, sufficiently massive protoplanets could acquire hydrogen-rich proto-atmospheres by capturing gas from the protoplanetary disk. Chemical equilibration among the atmosphere, magma ocean, and iron core plays a key role in determining the planet's interior composition. In this study, we investigate terrestrial planet formation under such primitive surface conditions. We conduct N-body simulations to model the collisional growth from protoplanets to planets, coupled with chemical equilibrium calculations at each giant impact event, where surface melting occurs. Our results show that planetary growth proceeds through a series of giant impacts, and the timing of these impacts relative to the dissipation of disk gas significantly influences the volatile budget. In particular, initial impacts, occurring while nebular gas is still present, can lead to excess hydrogen incorporation into the protoplanet's core. Subsequent impacts with hydrogen-poor bodies, after gas dispersal, can dilute this hydrogen content. This process allows for the formation of a planet with a hydrogen inventory consistent with Earth's current core. Our findings suggest that late giant impacts, occurring after the depletion of nebular gas, provide a viable mechanism for producing Earth-like interior compositions near 1 au.

Keywords: Earth (planet), Solar system evolution, Planetary science, N-body simulations, Planet formation
Spectroscopy of the Hamburg Meteorite, Michigan H4. Spectroscopic studies of the Hamburg (Michigan H4) meteorite using visible─near-infrared (VNIR), mid-infrared (MIR), Raman, and Mössbauer data reproduce the results of more conventional laboratory measurements of petrology and geochemistry. This combination provides general information on the mineral modes of silicates, although spectroscopy was performed on different splits of this meteorite, and varying results may be explained by heterogeneity that is typical of ordinary chondrites. Raman also detects small features assigned to first-order D and G carbon bands, while Mössbauer data show the presence of Fe oxides and carbides. The electron microprobe (EMPA) composition of olivine in this meteorite is accurately measured to be Fo81.3, while MIR and Raman closely agree with Fo80 and Fo82, respectively, and Mössbauer, at Fo60 − Fo70, is in the ballpark. Similarly, P. R. Heck et al. report pyroxenes with compositions of Fs16Wo1, while Raman suggests a somewhat similar composition of Fs28Wo0. Both VNIR and MIR detect the presence of small amounts of feldspar, while EMPA identifies its composition as An14Ab8Or5. VNIR data were matched to spectral libraries of meteorite and asteroid data and shown to closely match other L and H meteorites. The best spectral matches to the Michigan H4 meteorite are to asteroid classes L/H/LL/URE, EH/EL/AUB, and CO/CV from M. D. Dyar et al.; objects in this group are intermediate in semimajor axis lengths for their orbits. The results highlight the strengths and weaknesses of each technique and show their collective strength when applied together to a single meteorite sample.

Keywords: Asteroid belt, Carbonaceous chondrites, Gamma-ray spectroscopy, Electronic spectroscopy
Modeling Low-temperature Plasmas Simulating Titan's Atmosphere. In the study presented here, we model the gas phase chemistry induced by plasma discharge at low temperatures (150 K) in the NASA Ames COSmIC Simulation Chamber (COSmIC) using a 1D multifluid plasma model named COSmIC Plasma Reactivity and Ionization Simulation Model. Our model incorporates an extensive chemical reaction network to simulate the neutral─neutral and ion─neutral reactions occurring in the COSmIC experiments when using N2─CH4-based gas mixtures relevant to Titan's atmosphere. Our reaction network now includes crucial reactions involving the first electronically excited state of atomic nitrogen, recent electron collision cross sections, and radical chemistry. In particular, we have investigated the influence of C2H2 on the gas phase polymeric growth and the elemental composition of the chemical products, and we have compared our findings to recently published solid phase analyses. The modeling results are consistent with experimental measurements of N2─CH4─C2H2 plasmas on COSmIC, showing the production of C6Hx intermediates and precursors of larger organics, as well as methanimine in small concentration. Our numerical results point to cationic pathways enabling efficient intermediate-sized and nitrogen-rich C2H2-driven chemistry driving tholin production. Comparison of the modeled gas phase elemental composition with the elemental composition of the solid phase samples produced in COSmIC reveals similar trends, with C/N increasing when C2H2 is present in the gas mixture. Finally, our results demonstrate the importance of such synergistic studies using low-temperature plasma chemistry experiments combined with modeling efforts to improve our understanding of cold planetary environments.

Keywords: Astronomical models, Laboratory astrophysics, Titan, Reaction models
JWST Reveals Varied Origins between Jupiter's Irregular Satellites. We report JWST NIRSpec (0.7─5.1 μm) observations of eight Jovian irregular satellites across five orbital groups. We detect variation in the phyllosilicate content of the three largest members of the Himalia collisional family (Himalia, D ∼ 140 km, Elara, D ∼ 80 km, and Lysithea, D ∼ 40 km). Himalia contains complexed CO2 and overlapping absorption features from ∼2.7 to 3.6 μm that match laboratory samples of ammoniated phyllosilicates. Lysithea displays a simpler, single-minimum 3 μm feature caused by an unidentified absorber. Elara presents a 3 μm band that matches a simple average of Himalia and Lysithea. We argue that the Himalia parent body was heterogeneous and formed with materials similar to Ceres-like ammonium-bearing asteroids, consistent with suggestions from previous visible-wavelength observations. The satellites Carme, Sinope, and Themisto have colors and absorption features similar to "red" Jovian Trojans. The satellites Ananke, Pasiphae, and Lysithea each have absorption bands centered from 2.93 to 2.97 μm, intermediate between the longer-wavelength bands observed on Trojan asteroids and the shorter-wavelength bands commonly seen on phyllosilicate-rich C2 chondrites. These intermediate-wavelength absorptions are present in both Trojan-like families and the hydrated Himalia family, confounding a link to a single compositiont. The observed differences between Jupiter's irregular satellites and Trojans require one of two possibilities: (1) some Trojan parent bodies contained hydrated materials in their cores, or (2) some Jovian irregular satellites were not captured from the Trojan parent reservoir. Future searches for NH-bearing materials across the solar system and 3 μm studies of small-body collisional families may provide means to discriminate between these two hypotheses.

Keywords: Asteroids, Infrared spectroscopy, Small Solar System bodies, Natural satellites (Solar system), Jupiter trojans, Ceres, Trans-Neptunian objects, Irregular satellites
Charged Ejecta Clouds from Granular Beds after Slow Impacts. Low-velocity impacts are a significant process on all planetary surfaces, from rebounding particles on asteroids to saltating grains on Earth. Due to triboelectric effects, the material involved can be charged. We carried out experiments to study the net charge on ejecta emitted from a basalt sample with a particle size of 0.64 ± 0.24 mm during impacts with a steel sphere of 4.5 mm diameter and a mass of 0.36 g, and during impacts with basalt pebbles of 13─20 mm diameter and a mass of 0.5─2.6 g in air. The impact velocities were set to 2.2 ± 0.3 m s−1 and 3.7 ± 0.5 m s−1 for the steel impactors and to 3.6 ± 0.3 m s−1 and 2.5 ± 0.7 m s−1 for the basalt pebbles. The masses of the ejecta range between 10 and 600 mg. We find that the ejecta cloud charges regularly to tens of pC. There is a tendency toward negative polarity of the ejecta cloud. The impactor tends to charge positively. We do not see a significant dependence of the charge on the ejected mass. This suggests that the net charge is generated in direct contact between the impactor and the particles of the bed. The net cloud charge divided among the ejected grains would be small compared to the absolute charges on individual grains from grain─grain interactions found in other works. However, charges might add up in multiple collisions and influence the dynamics of grains, especially under low gravity.

Keywords: Impact phenomena, Surface processes, Charge transfer, Asteroid surfaces
Surface Binding Energies for Amorphous Plagioclase Feldspar Calculated Using Molecular Dynamics. Despite the well-established presence of amorphous compounds on planetary bodies such as the Moon and Mercury due to space weathering, the direct effect of atomic arrangement on the surface binding energies (SBEs) of elements on these bodies remains largely unexplored. Accurate SBE values are essential for reliably predicting sputtering yields and the energy distribution of ejecta. Here, we use molecular dynamics simulations to quantify SBEs for the different elements sputtered from amorphous atomic arrangements of the plagioclase feldspar end members, albite and anorthite, and compare them to their crystalline counterparts. Results show that while the mean elemental SBEs from amorphous surfaces are not significantly different from their crystalline counterparts, the random orientation in amorphous structures gives rise to a spectrum of bonding configurations, resulting in a distribution of SBEs with a wider range. This contrasts with the clearly discretized set of SBE values associated with the ordered atomic structure of crystalline surfaces. We then consider sputtering by H, He, and a solar wind combination of 96% H and 4% He. For each of these cases, we demonstrate that there is minimal difference (&lt;10% for albite and &lt;20% for anorthite) between the sputtering yields of amorphous and crystalline surfaces. We attribute these results to the presence of the same elemental bonds across different atomic arrangements, which leads to similar mean SBEs and, consequently, comparable sputtering yields.

Keywords: Planetary surfaces, Exosphere, Surface processes, The Moon, Mercury (planet)
Exploring the Interior Structure and Mode of Tidal Heating in Enceladus. Enceladus is among the most intriguing bodies in the solar system due to its astrobiological potential. Determining the extent and duration of habitability (i.e., sustained habitability) requires characterizing the interior properties and the level and distribution of tidal heating in Enceladus. Inferring the intensity of geophysical activity in the core has direct implications for the potential hydrothermal activity and supply of chemical species important for habitability to the ocean. We build a statistical framework to constrain the interior using estimates of libration, shape, heat flux, gravity, and total mass. We use this framework to examine the extent that geodetic measurements can improve our understanding of the interior structure, with an emphasis on partitioning of dissipation between the shell and the core. We quantify plausible ranges of gravitational (k2) and displacement (h2, l2) tidal Love numbers consistent with existing observations. We demonstrate that measuring k2 alone can only constrain the total tidally dissipated energy, not its radial distribution. However, measuring the amplitude and phase of h2 or l2 facilitates determining the extent of tidal dissipation in the shell and the core. We provide the precisions required for measuring k2, h2, and l2 that enable distinguishing between the main tidal heating scenarios, i.e., in the shell versus the core. We also explore the effect of the structural heterogeneities of the shell on the tidal response. Lastly, we evaluate the efficacy of future geodetic measurements to constrain key interior properties essential to understand the present-day (instantaneous) and long-term (sustained) habitability at Enceladus.

Keywords: Saturnian satellites, Solid body tides, Enceladus, Libration, Tides, Planetary interior, Habitable planets
Powerful Lightning on Venus Constrained by Atmospheric NO. Signs of lightning on Venus have long been sought, including by space missions and ground-based telescopes searching for optical flashes, plasma waves, or radio signatures. These efforts have yielded conflicting findings regarding the presence or absence of lightning in Venus's atmosphere. In this study, we adopt an indirect approach to constrain the prevalence of lightning on Venus using the chemical by-products it produces in Venus's atmosphere. Nitric oxide (NO) is a key tracer species of lightning, being exclusively generated by lightning in Venus's lower atmosphere. By calculating the present rate of atmospheric destruction of NO in Venus's atmosphere through photochemical-kinetic modeling, we constrain the lightning power required to sustain the estimated NO abundances on modern Venus. The reported NO constraints require lightning to generate at least 3 times the power released on Earth, consistent with either a higher rate of strikes, greater energy per strike, or a combination of both. Limited detections of optical flashes within the clouds could point to lightning striking deeper in the atmosphere and nearer the surface—with the result that its optical flashes are obscured by the clouds—driven by triboelectric charging during volcanic eruptions or wind interactions with surface sediments. Our findings underscore the importance for future missions of confirming lightning on Venus, either by verifying the below-cloud NO abundance or by detecting another unambiguous lightning signature, to provide the first definitive evidence of lightning on a rocky planet other than Earth.

Keywords: Atmospheric clouds, Planetary atmospheres, Venus, Atmospheric science, Planetary science, Lightning
First Use of Laser Ranging to Surface Retroreflectors for Orbit Determination: LRO-LOLA at the Moon. We document the first operational demonstration of two-way spacecraft-to-surface laser ranging using Laser Retroreflector Arrays (LRAs) for orbit determination (OD) of the Lunar Reconnaissance Orbiter (LRO). We detail how the Lunar Orbiter Laser Altimeter (LOLA) was operationally adapted to target and successfully range to several LRAs on the lunar surface. Although LOLA was not designed for this purpose, and despite many spacecraft constraints that limited the number of measurements we could collect, we demonstrate that incorporating these ranging observations into OD procedures yields tangible improvements in LRO's orbital solution. Our analysis yields two key findings: (1) systematic ranging to different types of surface LRAs from orbit is operationally feasible, and (2) such measurements provide valuable geodetic data for spacecraft navigation. This first demonstration is particularly timely as more LRAs are being deployed across the lunar surface through various international and commercial missions, while LiDAR technology continues to advance. Combined with the growing number of missions requiring Position, Navigation, and Timing services in lunar orbit, our findings indicate that spacecraft-to-LRA ranging could become an essential technique for navigation in the near future, complementing traditional Earth-based tracking methods.

Keywords: Orbit determination, Lunar geodesy