Sazuna/UAT_keywords huggingface dataset:
Predictions for the Dynamical States of the Didymos System before and after the Planned DART Impact. NASA's Double Asteroid Redirection Test (DART) spacecraft is planned to impact the natural satellite of (65803) Didymos, Dimorphos, at around 23:14 UTC on 2022 September 26, causing a reduction in its orbital period that will be measurable with ground-based observations. This test of kinetic impactor technology will provide the first estimate of the momentum transfer enhancement factor β at a realistic scale, wherein the ejecta from the impact provide an additional deflection to the target. Earth-based observations, the LICIACube spacecraft (to be detached from DART prior to impact), and ESA's follow-up Hera mission, to launch in 2024, will provide additional characterizations of the deflection test. Together, Hera and DART comprise the Asteroid Impact and Deflection Assessment cooperation between NASA and ESA. Here, the predicted dynamical states of the binary system upon arrival and after impact are presented. The assumed dynamically relaxed state of the system will be excited by the impact, leading to an increase in eccentricity and a slight tilt of the orbit, together with enhanced libration of Dimorphos, with the amplitude dependent on the currently poorly known target shape. Free rotation around the moon's long axis may also be triggered, and the orbital period will experience variations from seconds to minutes over timescales of days to months. Shape change of either body, due to cratering or mass wasting triggered by crater formation and ejecta, may affect β, but can be constrained through additional measurements. Both BYORP and gravity tides may cause measurable orbital changes on the timescale of Hera's rendezvous.

Keywords: Asteroid satellites, Asteroids, Asteroid dynamics
Dynamical Evolution of the Didymos-Dimorphos Binary Asteroid as Rubble Piles following the DART Impact. Previous efforts have modeled the Didymos system as two irregularly shaped rigid bodies, although it is likely that one or both components are in fact rubble piles. Here, we relax the rigid-body assumption to quantify how this affects the spin and orbital dynamics of the system following the DART impact. Given the known fundamental differences between our simulation codes, we find that faster rigid-body simulations produce nearly the same result as rubble-pile models in scenarios with a moderate value for the momentum enhancement factor, β (β ~ 3) and an ellipsoidal secondary. This indicates that the rigid-body approach is likely adequate for propagating the post-impact dynamics necessary to meet the DART Mission requirements. Although, if Dimorphos has a highly irregular shape or structure, or if β is unexpectedly large, then rubble-pile effects may become important. If Dimorphos's orbit and spin state are sufficiently excited, then surface particle motion is also possible. However, these simulations are limited in their resolution and range of material parameters, so they serve as a demonstration of principle, and future work is required to fully understand the likelihood and magnitude of surface motion.

Keywords: Near-Earth objects, Asteroid dynamics, Natural satellite dynamics, Orbits, Asteroid satellites, Celestial mechanics, N-body problem, Asteroid rotation, N-body simulations
Jupiter's Temperature Structure: A Reassessment of the Voyager Radio Occultation Measurements. The thermal structure of planetary atmospheres is an essential input for predicting and retrieving the distribution of gases and aerosols, as well as the bulk chemical abundances. In the case of Jupiter, the temperature at a reference level-generally taken at 1 bar-serves as the anchor in models used to derive the planet's interior structure and composition. Most models assume the temperature measured by the Galileo probe. However, those data correspond to a single location, an unusually clear, dry region, affected by local atmospheric dynamics. On the other hand, the Voyager radio occultation observations cover a wider range of latitudes, longitudes, and times. The Voyager retrievals were based on atmospheric composition and radio refractivity data that require updating and were never properly tabulated; the few existing tabulations are incomplete and ambiguous. Here we present a systematic electronic digitization of all available temperature profiles from Voyager, followed by their reanalysis, employing currently accepted values of the abundances and radio refractivities of atmospheric species. We find the corrected temperature at the 1 bar level to be up to 4 K greater than the previously published values, i.e., 170.3 ± 3.8 K at 12°S (Voyager 1 ingress) and 167.3 ± 3.8 K at 0°N (Voyager 1 egress). This is to be compared with the Galileo probe value of 166.1 ± 0.8 K at the edge of an unusual feature at 6.°57N. Altogether, this suggests that Jupiter's tropospheric temperatures may vary spatially by up to 7 K between 7°N and 12°S.

Keywords: Solar system formation, Radio occultation, Jupiter, Atmospheric refraction, Atmospheric composition
The ESA Hera Mission: Detailed Characterization of the DART Impact Outcome and of the Binary Asteroid (65803) Didymos. Hera is a planetary defense mission under development in the Space Safety and Security Program of the European Space Agency for launch in 2024 October. It will rendezvous in late 2026 December with the binary asteroid (65803) Didymos and in particular its moon, Dimorphos, which will be impacted by NASA's DART spacecraft on 2022 September 26 as the first asteroid deflection test. The main goals of Hera are the detailed characterization of the physical properties of Didymos and Dimorphos and of the crater made by the DART mission, as well as measurement of the momentum transfer efficiency resulting from DART's impact. The data from the Hera spacecraft and its two CubeSats will also provide significant insights into asteroid science and the evolutionary history of our solar system. Hera will perform the first rendezvous with a binary asteroid and provide new measurements, such as radar sounding of an asteroid interior, which will allow models in planetary science to be tested. Hera will thus provide a crucial element in the global effort to avert future asteroid impacts at the same time as providing world-leading science.

Keywords: Impact phenomena, Near-Earth objects, Asteroid dynamics, Asteroid satellites, Asteroid surfaces
Expected Investigation of the (65803) Didymos-Dimorphos System Using the RGB Spectrophotometry Data Set from the LICIACube Unit Key Explorer (LUKE) Wide-angle Camera. The Light Italian Cubesat for Imaging of Asteroids (LICIACube) is part of the NASA Double Asteroid Redirection Test (DART), the first mission aiming to demonstrate the applicability of the kinetic impactor method for planetary defense. The mission was launched on 2021 November 24 to perform the impact experiment on Dimorphos, the small secondary of the binary asteroid (65803) Didymos. The 6U LICIACube, stored as a piggyback of the DART spacecraft, is the first Italian mission operating in deep space managed by the Italian Space Agency that will witness the effects of the DART impact on Dimorphos. On board LICIACube, there is a suite of cameras that will perform imaging of Didymos and Dimorphos to investigate the DART impact effects and study the binary system. Among them, the LICIACube Unit Key Explorer (LUKE), a wide-angle camera coupled to an RGB Bayer pattern filter, will be pivotal to constrain the surface composition and heterogeneity of the binary system due to differences in surface properties linked with possible space weathering effects and/or the presence of exogenous material. Multiband photometric analysis of LUKE data and laboratory experiments in support of data interpretation will provide new insights on the binary asteroid nature and evolution. Moreover, photometric phase curve analysis will reveal the scattering properties of the granular surface medium providing important constraints for the microphysical properties of the Didymos-Dimorphos system. In this work, we will present the state of the art of the LUKE scientific activities with an overview of the instrument setup, science operations, and expected results.

Keywords: Near-Earth objects, Phase angle, Asteroids, RGB photometry, Laboratory astrophysics, Multivariate analysis, Near infrared astronomy
Atmospheric Gravitational Tides of Earth-like Planets Orbiting Low-mass Stars. Temperate terrestrial planets orbiting low-mass stars are subject to strong tidal forces. The effects of gravitational tides on the solid planet and that of atmospheric thermal tides have been studied, but the direct impact of gravitational tides on the atmosphere itself has so far been ignored. We first develop a simplified analytic theory of tides acting on the atmosphere of a planet. We then implement gravitational tides into a general circulation model of a static-ocean planet in a short-period orbit around a low-mass star-the results agree with our analytic theory. Because atmospheric tides and solid-body tides share a scaling with the semimajor axis, we show that there is a maximum amplitude of the atmospheric tide that a terrestrial planet can experience while still having a solid surface; Proxima Centauri b is the poster child for a planet that could be geophysically Earth-like but with atmospheric tides more than 500× stronger than Earth's. In this most extreme scenario, we show that atmospheric tides significantly impact the planet's meteorology-but not its climate. Two possible modest climate impacts are enhanced longitudinal heat transport and cooling of the lowest atmospheric layers. The strong radiative forcing of such planets dominates over gravitational tides, unlike moons of cold giant planets, such as Titan. We speculate that atmospheric tides could be climatologically important on planets where the altitude of maximal tidal forcing coincides with the altitude of cloud formation and that the effect could be detectable for non-Earth-like planets subject to even greater tides.

Keywords: Tides, Exoplanet atmospheres
Preimpact Mutual Orbit of the DART Target Binary Asteroid (65803) Didymos Derived from Observations of Mutual Events in 2003-2021. We modeled photometric observations of mutual events (eclipses and occultations) between the components of the binary near-Earth asteroid (65803) Didymos, the target of the Double Asteroid Redirection Test (DART) space mission, which were taken from 2003 to 2021. We derived parameters of the modified Keplerian mutual orbit (allowing for a quadratic drift in the mean anomaly, which is presumably caused by an interplay between the BYORP effect and mutual tides, or by differential Yarkovsky force) of the secondary, called Dimorphos, around the Didymos primary and estimated its diameter. The J2000 ecliptic longitude and latitude of the orbital pole are 320.°6 ± 13.°7 and -78.°6 ± 1.°8, respectively, and the orbital period is 11.921624 ± 0.000018 hr at epoch JD 2,455,873.0 (asterocentric UTC; all quoted uncertainties correspond to 3σ, except the density estimate below). We obtained the quadratic drift of the mean anomaly of 0.15 ± 0.14 deg yr-2. The orbital eccentricity is ≤0.03. We determined the ecliptic longitude and latitude of the radius vector of Dimorphos with respect to Didymos at the nominal time of the DART impact to Dimorphos (JD 2,459,849.46875 geocentric UTC) to be 222.°8 ± 7.°0 and -1.°6 ± 4.°2, respectively. We also estimated the bulk density of the system to be 2.37 ± 0.30 g cm-3 (1σ uncertainty).

Keywords: Asteroid satellites, Light curves, Photometry
Constraining the Internal Structures of Venus and Mars from the Gravity Response to Atmospheric Loading. The gravity fields of celestial bodies that possess an atmosphere are periodically perturbed by the redistribution of fluid mass associated with atmospheric dynamics. A component of this perturbation is due to the gravitational response of the body to the deformation of its surface induced by the atmospheric pressure loading. The magnitude of this effect depends on the relation between the loading and the response in terms of geopotential variations measured by the load Love numbers. In this work, we simulate and analyze the gravity field generated by the atmospheres of Venus and Mars by accounting for different models of their internal structure. By precisely characterizing the phenomena that drive the mass transportation in the atmosphere through general circulation models, we determine the effect of the interior structure on the response to the atmospheric loading. An accurate estimation of the time-varying gravity field, which measures the atmospheric contribution, may provide significant constraints on the interior structure through the measurement of the load Love numbers. A combined determination of tidal and load Love numbers would enhance our knowledge of the interior of planetary bodies, providing further geophysical constraints in the inversion of internal structure models.

Keywords: Gravitational fields, Planetary atmospheres, Atmospheric tides, Tides, Planetary interior
Mach and Froude Numbers on Mars. Mars atmospheric global circulation models exhibit transonic jet streaks during northern winter, which motivates this study of the Mach number, Ma (the ratio of flow speed to the speed of sound), and Froude number, Fr (the ratio of flow speed to the speed of buoyancy waves), as a function of season and location. Two global reanalyses spanning Mars Years (MY) 24 to 32 are used as input, EMARS and OpenMARS. The study's vertical coordinate is potential temperature, θ, ranging from θ = 400 to 1100 K (from z ≈ 32 to 66 km); the floor is set to the lowest level that avoids intersecting mountains. Area-weighted global means and standard deviations and 5 yr temporal means using the complete years MY 25, 26, 29, 30, and 31 are compared. EMARS and OpenMARS show general agreement below θ = 700 K (z ≈ 53 km), where the observational constraints are strongest, but can vary significantly at higher levels. Both reanalyses contain transonic jet streaks in every northern winter sampled. The Fr signal is roughly twice the Ma number signal, as expected where the temperature lapse rate is small compared to the dry adiabatic lapse rate. Mach numbers are similar in both reanalyses but show larger year-to-year variability in OpenMARS. Maps of standard deviations indicate a depression between the main peaks in Tharsis and higher variability in Mare Boreum than Mare Australe. The main conclusion is that the atmosphere of Mars routinely operates in the compressible regime (0.3 &lt; Ma &lt; 0.8), unlike Earth. Aspects of all flow-speed meteorology are discussed.

Keywords: Mars, Jets, Planetary atmospheres
Exploring Jupiter's Polar Deformation Lengths with High-resolution Shallow Water Modeling. The polar regions of Jupiter host a myriad of dynamically interesting phenomena, including vortex configurations, folded-filamentary regions (FFRs), and chaotic flows. Juno observations have provided unprecedented views of the high latitudes, allowing for more constraints to be placed upon the troposphere and the overall atmospheric energy cycle. Moist convective events are believed to be the primary drivers of energetic storm behavior as observed on the planet. Here we introduce a novel single-layer shallow water model to investigate the effects of polar moist convective events at high resolution, the presence of dynamical instabilities over long timescales, and the emergence of FFRs at high latitudes. We use a flexible, highly parallelizable, finite difference hydrodynamic code to explore the parameter space set up by previous models. We study the long-term effects of deformation length (L  d ), injected pulse size, and injected geopotential. We find that models with L  d  beyond 1500 km (planetary Burger number, Bu = 4.4 × 10‑4) tend to homogenize their potential vorticity in the form of dominant stable polar cyclones, while lower-L  d  cases tend to show less stability with regard to Arnol'd-type flows. We also find that large turbulent forcing scales consistently lead to the formation of high-latitude FFRs. Our findings support the idea that moist convection occurring at high latitudes may be sufficient to produce the dynamical variety seen at the Jovian poles. Additionally, derived values of localized horizontal shear and L  d  may constrain FFR formation and evolution.

Keywords: Hydrodynamical simulations, Planetary polar regions, Hydrodynamics, Planetary atmospheres, Solar system gas giant planets, Jupiter
The Effects of Methane Clathrates on the Thermal and Seismic Profile of Titan's Icy Lithosphere. We investigate the effects of methane clathrates on Titan's thermal and seismic structure. The Dragonfly mission is planned to arrive at Titan in 2033 with a payload that includes a seismic package. The seismic instruments are tasked with recording seismic events and recovering the internal structure. Here, we explore whether differences in thermal and seismic profiles between a pure water ice shell and an ice shell with a clathrate lid could be detectable with seismic instrumentation. Due to their lower thermal conductivity, clathrates reduce the conductive lid thickness thus altering the thermal profile. The differences between seismic velocities of clathrates and pure water ice, coupled with changes in the thermal profile, indicate the clathrate lid will create lower seismic velocities, particularly for the upper 10 km of the surface ice shell. The differences in P and S velocity at the surface are 2.9% and 4.5%, respectively, and reach up to 8.4% (for both P and S) at a depth of 9.6 km. Due to changes in thermal profile, the seismic attenuation of the ice shell will change such that clathrates will suppress surface wave amplitudes relative to the pure water ice model. The clathrate lid will further create minor changes (≤2.0%) in the surface wave dispersion curves. Dragonfly, or other future seismic investigations, could provide evidence for or against the presence of a clathrate lid by constraining the thermal and seismic profile of Titan's ice shell, by measuring the relative amplitudes of the surface to body waves, or by constraining the surface wave dispersion with high accuracy and precision.

Keywords: Surface ices, Planetary interior, Titan, Planetary structure
Identifying Shadowing Signatures of C Ring Ringlets and Plateaus in Cassini Data from Saturn's Ionosphere. For orbits 288 and 292 of Cassini's Grand Finale, clear dips (sharp and narrow decreases) are visible in the ${{\rm{H}}}_{2}^{+}$ densities measured by the Ion and Neutral Mass Spectrometer (INMS). In 2017, the southern hemisphere of Saturn was shadowed by its rings and the substructures within. Tracing a path of the solar photons through the ring plane to Cassini's position, we can identify regions in the ionosphere that were shadowed by the individual ringlets and plateaus (with increased optical depths) of Saturn's C ring. The calculated shadowed altitudes along Cassini's trajectory line up well with the dips in the ${{\rm{H}}}_{2}^{+}$ data when adjusting the latter based on a detected evolving shift in the INMS timestamps since 2013, illustrating the potential for verification of instrument timings. We can further estimate the mean optical depths of the ringlets/plateaus by comparing the dips to inbound ${{\rm{H}}}_{2}^{+}$ densities. Our results agree well with values derived from stellar occultation measurements. No clear dips are visible for orbits 283 and 287, whose periapsides were at higher altitudes. This can be attributed to the much longer chemical lifetime of ${{\rm{H}}}_{2}^{+}$ at these higher altitudes, which in turn can be further used to estimate a lower limit for the flow speed along Cassini's trajectory. The resulting estimate of ~0.3 km s-1 at an altitude of ~3400 km is in line with prior suggestions. Finally, the ringlet and plateau shadows are not associated with obvious dips in the electron density, which is expected due to their comparatively long chemical (recombination) lifetime.

Keywords: Space plasmas, Saturn, Planetary rings, Planetary ionospheres
Searching for Binary Asteroids in Pan-STARRS1 Archival Images. We developed two different point-spread function (PSF) analysis techniques for discovering wide separation binary asteroids in wide-field surveys. We then applied these techniques to images of main belt asteroids in the 4-60 km size range captured by Pan-STARRS1. Johnston lists fewer than 10 known binaries in this size range with separations greater than 10% of the primary's Hill radius, so discovering more wide binary asteroids is crucial for understanding the limits of binary stability and improving our knowledge of asteroid masses. We analyzed each image by (i) comparing the major axis orientation of the asteroid's elliptical PSF to its nonsidereal rate on the sky and (ii) comparing the one-dimensional median profile created by collapsing the image along the asteroid's direction of motion to that of nearby field stars. For both methods, we flagged any results that deviated significantly from the expected measurements of single asteroids, and those targets with the most flags were identified as binary candidates for confirmation with high-acuity imaging.

Keywords: Asteroid satellites, Main belt asteroids, Sky surveys, Astronomical techniques
Simulation of Freezing Cryomagma Reservoirs in Viscoelastic Ice Shells. Brine reservoirs in Europa's icy crust, if they exist, could represent the most accessible liquid water bodies in the outer solar system. Any potential subsurface reservoirs are key for the exploration of ocean worlds and the search for habitability and life beyond Earth. Previous studies have demonstrated that freezing cryoreservoirs might trigger eruptions due to the pressurization associated with volume change as liquid water expands to become water ice, but those studies did not take into account the deformation of the reservoir wall. Viscoelastic deformation of the wall can act to accommodate the growing overpressure and prevent eruptions. Here we utilize a semianalytical numerical approach to calculate the pressure-induced deformation of a freezing cryoreservoir on Europa as a function of the far-field ice temperature. We find that shallow reservoirs located in relatively cold ice deform slightly and can be pressurized by freezing, but that deeper reservoirs located in warmer ice deform more easily and in some cases cannot reach the threshold overpressure required for spontaneous eruption. We identify a transition depth around 4-8 km depending on the reservoir radius, assuming a conductive ice shell structure consistent with current best estimates. Further, we find that shallow lens-shaped reservoirs may store a large volume of cryomagma and can be easily pressurized by freezing; they represent the best candidates for the mobilization of cryovolcanic material at Europa's surface.

Keywords: Natural satellite surfaces, Volcanism, Europa