Sazuna/UAT_keywords huggingface dataset:
Effect of a Surficial Porous Brittle Layer on the Dynamics and Equilibrium Thickness of Europa's Ice Shell. Tectonic and cryovolcanic features on Europa suggest a dynamically active ice shell with a highly deformable near-surface brittle layer. Shell thickness estimates based on geological interpretation and thermal modeling vary from 10 km to more than 30 km. The surface activity is probably caused by Jupiter's tidal forces, whose interplay with heat transfer processes still remains poorly understood. We modeled the dynamics and heat transfer of the ice shell, consistently including a variety of ice/ocean crystallization/melting processes and the effect of a superficial brittle porous layer. For tidal heat production corresponding to current orbital eccentricity, we obtained equilibrium thicknesses between 20 and 80 km depending on the assumed reference viscosity values. We show that the presence of a 1─2 km surficial porous layer reduces the average equilibrium thickness by 5─20 km while simultaneously enhancing the convective dynamics, resulting in much steeper near-surface thermal gradients and higher surface heat flux. The 240 K isotherm is predicted to shift closer to the surface, reaching depths of 10─15 km in the presence of a surficial porous layer, favoring the possible generation of eutectic brines at shallow depths and lithospheric breakups. For highly convecting models, the depth of the 240 K isotherms can be as shallow as 3─4 km, with surface heat flux exceeding 70 mW m−2. We anticipate that any lateral variation in the porous layer thickness should result in significant variations in the overall ice shell thickness and convective dynamics, which could be revealed by future measurements by Europa Clipper and JUICE.

Keywords: Ice phases, Europa, Planetary geology, Tides, Planetary interior
Spin Parameters and Shape Models of Near-Earth Asteroids (4660) Nereus, (21088) Chelyabinsk, (66146) 1998 TU3, and (297418) 2000 SP43. We present our shape and rotational characterization of four near-Earth asteroids observed as part of the Visible NEAs Observations Survey. This work includes 61 new light curves obtained between 2020 June and 2024 September for asteroids (21088) Chelyabinsk and (66146) 1998 TU3 and the potentially hazardous asteroids (4660) Nereus and (297418) 2000 SP43. We combine these observations with archival data to derive their shape models, spin parameters, and refined rotation periods using a light-curve inversion method. Our derived rotational periods are consistent with previously published values for all the objects. We present constant-period models for each asteroid, while for (66146) 1998 TU3 we detect a possible Yarkovsky─O'Keefe─Radzievskii─Paddack (YORP) acceleration of υ ≃ 2.05 × 10−8 rad day−2, potentially adding it to the short list of asteroids known to experience the YORP effect.

Keywords: Amor group, Near-Earth objects, Asteroids, Photometry, Aten group, Apollo group
The Sesquinary Catastrophe on Deimos Can Reconcile Its Excited Past with Its Dynamically Cool Present. The origins of the Martian moons Phobos and Deimos are highly debated, and hypotheses include formation from an impact-generated circum-Martian disk and formation from capture of asteroids. With the impact scenario, Deimos (or its precursors) was formed or was pushed out beyond the synchronous orbit of Mars. Moons interior to the synchronous orbit, including Phobos (or its precursors), would tidally evolve, and resonances between these moons could potentially excite Deimos's orbit. This contradicts Deimos's present-day orbit of low eccentricity (0.00027) and moderate inclination (1 .° 8 to the Laplace plane). Tidal dissipation within Deimos is too inefficient for eccentricity damping, and without alternative mechanisms, Deimos's present-day orbit places strong constraints on the evolution of any inner moons. We propose that a runaway collisional cascade called the "sesquinary catastrophe" acts as a natural barrier that prevents Deimos from having a more excited orbit. Using N-body simulations with collisional fragmentation, we show that if Deimos were more excited, it would undergo a sesquinary catastrophe and break apart into a Roche-exterior debris disk. Using a measure of sesquinary orbital excitation called q, our simulations and previous works suggest that breakup occurs for q ≳ 8 on timescales of ∼103−104 yr. If Deimos was destroyed in a sesquinary catastrophe and reaccreted from a (likely collisionally) damped debris disk, it should be a porous sand-pile moon, consistent with its smooth surface. The sesquinary catastrophe can be applied to other Deimos-like planetary moons at q ≳ 8.

Keywords: Collisional processes, Martian satellites, Natural satellite dynamics, Natural satellite formation, Natural satellite evolution
Penetration Law in Loose Granular Medium for the Chang'E 5 and Chang'E 6 Footpad. This study investigates the penetration behavior of the footpads used in the Chang'e-5 (CE-5) and Chang'e-6 (CE-6) lunar probes when interacting with granular materials. Through a series of controlled impact experiments conducted using a full-scale footpad model, the influence of the impact height, impactor mass, landing velocity, and the properties of the granular medium on the penetration depth is investigated. The results yield an empirical formula for predicting the penetration depth of the CE-5/-6 footpad from the impactor mass, landing velocity, footpad area, and the internal friction angle of the granular material under impact. A validation experiment conducted on lunar regolith simulant verified that the empirical formula can accurately predict the internal friction angle of granular material. The maximum deviation between the predicted values of the lunar soil simulant and those measured by conventional consolidated drained triaxial tests is 3 .° 3 (6.8%). Additional experiment results show that the impact depth of the medium, to which the impact energy attenuates to a negligible level, is about 15.2 times the penetration depth of the footpad. These findings offer an approach for in-situ measurement of the friction angles of the lunar soils at the landing sites of the CE-5/-6 probes and probes of future missions.

Keywords: Impact phenomena, Lunar surface, Lunar probes
Remote Compositional Analyses of Space-weathered Lunar Maria. Visible-to-shortwave infrared (VSWIR) reflectance spectroscopy has revolutionized our understanding of planetary surface compositions. However, space-weathering processes on airless bodies complicate quantitative compositional analyses. Here, we present a framework to isolate the signatures of space weathering in VSWIR spectra of lunar maria by leveraging radiative transfer modeling under the assumptions that (i) a space-weathered target can be expressed as a mixture of fresh and fully space-weathered components and (ii) remaining signatures can be modeled by including agglutinates as an end-member component. We first validate this approach against laboratory spectra of space-weathered Apollo mare soils of known mineral compositions using a probabilistic Markov Chain Monte Carlo implementation of the Hapke radiative transfer model. Second, we illustrate how this approach can be applied to orbital Moon Mineralogy Mapper data. The proposed space-weathering correction workflow for lunar maria could be expanded to other lunar lithologies and applied to existing and future data sets.

Keywords: Infrared spectroscopy, Lunar maria, Space weather, Remote sensing, Lunar mineralogy, Spectroscopy
The Prospects for Gravitational Seismology at Uranus with an Orbiting Spacecraft. We study the feasibility of conducting gravitational seismology at Uranus, that is, of detecting and characterizing Uranian normal-mode oscillations through their perturbations on the trajectory of an orbiting spacecraft. Characterizing such oscillations has the potential to provide important constraints on models of the interior structure of the planet. We create a realistic, synthetic radio science dataset that includes the effect of gravitational perturbations on the orbiter exerted by normal modes. The accelerations produced by these perturbations are then used to compute the orbital torque that the modes exert on the spacecraft along its simulated trajectory. We compare the component of this torque parallel to the planetary spin axis to an analytical model, and examine the accuracy and precision to which the mode parameters can be recovered. Assuming an orbit with an eccentricity of 0.98 and an inclination of 45° passing between the planet and the inner edge of the  ζ  ring, and a noise level similar to that associated with the Juno radio science experiment at Jupiter, we demonstrate that we are able to recover mode frequencies to within 1% and amplitudes and phases to within 20% and 10%, respectively, of their true values over the course of a typical gravity-science experiment when one or two normal modes dominate the spectrum. We conclude that gravitational seismology can add valuable information concerning Uranus's normal modes, and recommend further exploration of its potential for revealing mode properties when the spectrum contains many modes of similar amplitude.

Keywords: Gravitational fields, Orbiters, Planetary interior, Uranus
Model for Determining the Origin of Lunar Volatiles Based on Their Composition: Application to NASA's VIPER and Other Landed Missions. Lunar volatiles provide a potentially pristine record of the history of the Earth─Moon system in terms of both geologic activity and delivery of volatiles from the outer solar system. Efforts to return humans to the Moon present an unprecedented opportunity to determine the origin of volatiles stored in the ice stability regions but also pose a threat to the scientific value of these volatiles and the lunar exosphere because of the irreversible modification that human exploration will have on the polar volatile ecosystem. We outline here a model for using lunar volatile composition measurements to determine constraints on the origin of lunar volatiles. When applied to results returned by future missions, the results can help trace the history of lunar volcanic activity, solar wind surface chemistry, and volatile delivery to the Earth and Moon through impacts of comets, asteroids, and micrometeoroids. Comprehensive measurements of lunar volatile composition, like those that could be collected by NASA's Volatiles Investigating Polar Exploration Rover mission, are urgently needed before anthropogenic activity permanently compromises the scientific value of lunar volatiles.

Keywords: Lunar composition, The Moon, Lunar impacts, Comet volatiles , Earth-moon system, Irregular natural satellites (Extrasolar)
Determination of Venus's Rotation State Using Radio-tracking Data from the Venus Express Spacecraft. Despite its similarities to Earth, our understanding of Venus remains limited, particularly regarding its long retrograde rotation period. This has been measured using both Earth-based and in-orbit methods. However, the values obtained exhibit significant variations that cannot be explained by models of various physical mechanisms that could affect the rotation period of Venus. In this study, we present a new determination of the rotation period of Venus based on the precise orbit determination method applied to the radio-tracking data of the Venus Express (VEX) spacecraft. This method consists of a least-squares adjustment of the difference between Doppler data collected by ground-based stations and simulated Doppler data from a force model governing the spacecraft's motion. We find a rotation period of 243.02064 ± 0.0010 days, which is consistent with results from studies using tracking data from previous orbiters, and with Earth-based radar techniques for the same period covered by the VEX tracking dataset. An attempt was also made to adjust other parameters, including the precession rate, the gravitational field, and the Love number k2. Nevertheless, no reliable results for these parameters could be obtained due to the lack of tracking data in the low altitude part of the highly eccentric orbit of VEX. The upcoming Venus missions, such as VERITAS (NASA) and EnVision (ESA) are expected to provide accurate Doppler tracking measurements that will improve our understanding of the planet.

Keywords: Venus, Orbit determination, Planetary science, Planetary probes
The Effect of Colored Noise on Doppler Measurements for Planetary Geodesy: Application to the VERITAS Gravity Science Experiment. Measurements of the Doppler shift of a carrier signal have always been the basis of radio science experiments, particularly for planetary gravity field recovery. Doppler observables are affected by correlated (colored) noise; however, standard orbit estimation filters assume that the noise is white and Gaussian. This assumption simplifies the code and reduces the runtime, as the weight matrix is diagonal. In this work, we present a method for incorporating colored noise into least-squares estimation filters by constructing a full noise covariance matrix that reflects the spectral characteristics of all contributing error sources, guaranteeing the proper estimation of parameters and their associated uncertainties. We apply this methodology to the gravity science experiment of NASA's upcoming Venus Emissivity, Radio Science, InSAR, Topography, And Spectroscopy (VERITAS) mission. Our analysis finds that the white noise assumption is valid for VERITAS—thus supporting the robustness of earlier simulation results. The approach, however, is general and particularly valuable for future missions in which colored noise, such as plasma-induced red noise, dominates the Doppler error budget.

Keywords: Gravitational fields, Venus, Solar system terrestrial planets, Planetary science, Orbit determination
Nucleus Ice Associations in Comets Derived from Spatially Resolved Properties of Volatile Gases in the Coma. Under favorable conditions, high-resolution long-slit infrared spectroscopic observations of comets can provide information on how ices are associated within the nucleus from spatially resolved properties of volatiles in the coma. In this study, we demonstrate the utility of this technique by investigating two Jupiter-family comets that were observed close to Earth—73P-Schwassmann─Wachmann (fragments B and C) and 103P/Hartley 2—providing high spatial resolution from ground-based observations. Spectra of these comets were acquired with NIRSPEC at the W. M. Keck Observatory. Molecular emissions were sufficiently strong to obtain spatial distributions of column densities and rotational temperatures for H2O, C2H6, HCN, and CH3OH (for 103P only). Comparison of 73P-B and 73P-C coma properties and nucleus associations test the heterogeneity of processes in comets that were originally part of a single nucleus. The spatial distributions of molecular column densities and rotational temperatures are notably similar in 73P-B and 73P-C despite different activity levels, providing additional and independent evidence of a remarkably homogeneous 73P parent nucleus. Comparison of coma properties and nucleus associations in 73P and 103P test the heterogeneities of processes between comets with very different chemical compositions. Both comets show strong evidence of abundant coma icy grains that contain less-abundant volatiles in addition to H2O. Because icy grains are constituents of the nucleus, the presence of volatiles within these grains provides evidence for how ices are associated within the nuclei of these comets. The spatial distributions of molecular column densities and rotational temperatures suggest different nucleus ice associations for 73P and 103P.

Keywords: Ice composition, Infrared spectroscopy, Short period comets, Chemical abundances, Neutral coma gases, Comets
An Integrated Framework for Global Detection and Quantification of Lunar Pyroclastic Deposits. Lunar pyroclastic deposits (LPDs) composed of Fe─Ti-bearing volcanic glasses are considered one of the best proxies to understand the primitive lunar mantle composition. These deposits are characterized by very low albedo and smooth surfaces associated with volcanic landforms. While regional LPDs can be identified based on these features, the approach is inadequate for detecting localized LPDs. The spectral signatures of volcanic glasses overlap with the common lunar minerals in the visible-to-near-infrared wavelength range, also making their detection challenging through remote observations. In this work, we propose a framework focusing on systematic identification of LPDs by incorporating morphological context with a newly derived spectral-parameter-based false-color-composite scheme using Moon Mineralogy Mapper (M3) data. Additionally, for the first time, we applied a probabilistic hyperspectral unmixing approach for remote estimation of volcanic glass abundances within LPDs. We evaluated this integrated framework on the well-known regional LPD at the Aristarchus crater region. Our result effectively detected the spatial extent of pyroclasts with an estimation of ∼75 wt% volcanic glasses across the identified deposit. We applied this approach to the M3 global mosaic (∼1.5 km pixel−1) and successfully detected several known localized and regional LPDs. Out of those, five locations were mentioned with their respective volcanic glass concentrations. The developed framework can lead to a comprehensive global identification and detailed quantitative analysis for characterization and classification of the LPDs. This approach will advance our understanding of the complex nature of lunar explosive volcanism and the geological evolution of the Moon.

Keywords: Lunar composition, The Moon, Remote sensing, Lunar mineralogy, Volcanism
Photochemistry in Jupiter's Ionosphere: Insights from Simultaneous <inline-formula> <mml:math><mml:msubsup><mml:mrow><mml:mi>H</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msubsup></mml:math> </inline-formula> and Electron Density Observations during Juno Perijove 54. Observations of continuous vertical electron and ion distributions at Jupiter were obtained simultaneously for the first time on 2023 September 7 UTC. On that date, Juno performed a radio occultation experiment and, in parallel, JWST and Keck scanned Jupiter's limb, focused on characterizing H 3+ . Here, using Keck infrared spectra, we derive constraints on H 3+  densities and temperatures. While on-disk column densities are roughly constant with latitude, with a mean value of (5.7 ± 2.1) × 1015 m−2, temperatures decrease smoothly from 774 ± 50 K at high latitude to 683 ± 28 K at low latitude. Vertical H 3+  temperatures are comparable to their on-disk values and mostly isothermal. Keck spectra sampled Jupiter's dawn limb, finding H 3+  volumetric number densities of (1─40) × 108 m−3 with peak altitudes near 1500 km. Comparison with the Juno electron altitude density profile confirms Jupiter's ionosphere is proton dominated. Ionospheric model simulations that can broadly replicate observed plasma densities indicate that field-aligned vertical transport driven by neutral winds is primarily responsible for the observed high-altitude peak. We use model outputs, validated by comparison with plasma observations, to demonstrate that H 3+  is in photochemical equilibrium (PCE) below ∼1600 km altitude in Jupiter's ionosphere. PCE analysis further reveals that the diurnal peak in  NH3+  can occur before noon, that peak electron densities should generally be &lt;6 × 1011 m−3, and that rapidly varying auroral H 3+  emissions can be explained by narrow (&lt;100 km) layers of H 3+  just above the homopause produced by energetic particle precipitation.

Keywords: Planetary ionospheres, Upper atmosphere, Infrared spectroscopy, Radio occultation, Jupiter, Ground-based astronomy
Col-OSSOS: Investigating the Origins of Different Surfaces in the Primordial Kuiper Belt. The Colours of the Outer Solar System Origins Survey (Col-OSSOS) measured the optical/near-IR colors of a brightness-complete sample of trans-Neptunian objects (TNOs). Like previous surveys, this one found a bimodal color distribution in TNOs, categorized as red and very red. Additionally, this survey proposed an alternative surface classification scheme: FaintIR and BrightIR. Cold classical TNOs mostly have very red or FaintIR surfaces, while dynamically excited TNOs show a mixture of surfaces. This likely indicates that formation locations and proximity to the Sun influenced surface characteristics and color changes. Our study combines the data from Col-OSSOS with two dynamical models describing the formation of the Kuiper Belt during Neptune's migration. We investigate the proposed surface-color-changing line and explore the distribution of different surfaces within the primordial disk. By comparing radial color transitions across various scenarios, we explore the origins of surface characteristics and their implications within the context of BrightIR and FaintIR classifications. Moreover, we extend our analysis to examine the distribution of these surface classes within the present-day Kuiper Belt, providing insights into the configuration of the early solar system's planetesimal disk prior to giant planet migration. We find that the most likely primordial disk compositions are inner neutral/outer red (with transition  30.0−1.2+1.1  au) and inner BrightIR/outer FaintIR (with transition  31.5−1.2+1.1  au).

Keywords: Kuiper belt, Small Solar System bodies, Trans-Neptunian objects
Spectral Evidence for Recent/Ongoing Activity in Mercury's Praxiteles Basin. Mercury's surface, as revealed by the MESSENGER probe, lacks distinctive absorption features in the visible─near-infrared spectral range, except for hollows that display a 630 nm feature ascribed to sulfides. The general absence of spectral features makes inference of its surface mineralogical composition challenging. We inspected the Praxiteles impact basin with newly photometrically corrected MDIS data, removing the influence of topographic shading in the spectra. We detected an 830 nm absorption feature, spectrally compatible with low Fe content minerals. The morphological and spectral correlations suggest that the 830 nm band is linked to geologically recent, or even ongoing, exposure of material, as well as to the early stage of hollow formation. These results provide insight into the subsurface composition of Mercury and imply a crust material locally more oxidized than previously thought.

Keywords: Planetary mineralogy, Infrared spectroscopy, Spectroscopy, Mercury (planet)
Modeling the Meteoroid Environment Far from the Ecliptic Plane. We describe a new version (numbered 3.1) of NASA's Meteoroid Engineering Model, in which we extend the model to handle locations that lie more than a few degrees in latitude off the ecliptic plane. We provide our algorithms for computing the spatial density and directionality of meteoroids far from the ecliptic and discuss their applications. In particular, we demonstrate how correct modeling of the out-of-ecliptic environment is critical for accurately assessing the risk posed by meteoroids to solar observation missions such as Solaris.

Keywords: Meteoroids