Sazuna/UAT_keywords huggingface dataset:
After DART: Using the First Full-scale Test of a Kinetic Impactor to Inform a Future Planetary Defense Mission. NASA's Double Asteroid Redirection Test (DART) is the first full-scale test of an asteroid deflection technology. Results from the hypervelocity kinetic impact and Earth-based observations, coupled with LICIACube and the later Hera mission, will result in measurement of the momentum transfer efficiency accurate to ~10% and characterization of the Didymos binary system. But DART is a single experiment; how could these results be used in a future planetary defense necessity involving a different asteroid? We examine what aspects of Dimorphos's response to kinetic impact will be constrained by DART results; how these constraints will help refine knowledge of the physical properties of asteroidal materials and predictive power of impact simulations; what information about a potential Earth impactor could be acquired before a deflection effort; and how design of a deflection mission should be informed by this understanding. We generalize the momentum enhancement factor β, showing that a particular direction-specific β will be directly determined by the DART results, and that a related direction-specific β is a figure of merit for a kinetic impact mission. The DART β determination constrains the ejecta momentum vector, which, with hydrodynamic simulations, constrains the physical properties of Dimorphos's near-surface. In a hypothetical planetary defense exigency, extrapolating these constraints to a newly discovered asteroid will require Earth-based observations and benefit from in situ reconnaissance. We show representative predictions for momentum transfer based on different levels of reconnaissance and discuss strategic targeting to optimize the deflection and reduce the risk of a counterproductive deflection in the wrong direction.

Keywords: Impact phenomena, Near-Earth objects, Asteroids, Asteroid satellites, Asteroid surfaces
Transmission of a Seismic Wave Generated by Impacts on Granular Asteroids. In this paper, we use a soft-sphere discrete element method code to simulate the transmission and study the attenuation of a seismic wave. Then, we apply our findings to the different space missions that have had to touch the surface of different small bodies in the solar system. Additionally, we do the same in regard to the seismic wave generated by the hypervelocity impacts produced by the DART and Hayabusa2 missions once the shock wave transforms into a seismic wave. We find that even at very low pressures, such as those present in the interior of asteroids, the seismic wave speed can still be on the order of hundreds of meters per second depending on the velocity of the impact that produces the wave. As expected from experimental measurements, our results show that wave velocity is directly dependent on P 1/6, where P is the total pressure (confining pressure plus wave-induced pressure). Regardless of the pressure of the system and the velocity of the impact (in the investigated range), energy dissipation is extremely high. These results provide us with a way to anticipate the extent to which a seismic wave could have been capable of moving some small particles on the surface of a small body upon contact with a spacecraft. Additionally, this rapid energy dissipation would imply that even hypervelocity impacts should perturb only the external layer of a self-gravitating aggregate on which segregation and other phenomena could take place. This would, in turn, produce a layered structure of which some evidence has been observed.

Keywords: Impact phenomena, Microgravity, Asteroids, Regolith, N-body simulations, Planetary structure
The Age and Erosion Rate of Young Sedimentary Rock on Mars. The Medusae Fossae Formation (MFF) is an enigmatic sedimentary unit near the equator of Mars, with an uncertain formation process and absolute age. Due to the heavily wind-eroded surface, it is difficult to determine the absolute model age of the MFF using a one-parameter model based on the crater size-frequency distribution function with existing crater count data. We create a new two-parameter model that estimates both age and a constant erosion rate (β) by treating cratering as a random Poisson process. Our study uses new crater count data collected from Context Camera imagery for both the MFF and other young equatorial sedimentary rock. Based on our new model, the Central MFF formed &gt;1.5 Gyr ago and had low erosion rates (&lt;650 nm yr-1), whereas the East MFF, Far East MFF, and Zephyria Planum most likely formed &lt;1.5 Gyr ago and had higher erosion rates (&gt;740 nm yr-1). The top of Aeolis Mons (informally known as Mount Sharp) in Gale Crater and Eastern Candor have relatively young ages and low erosion rates. Based on the estimated erosion rates (since fast erosion permits metastable shallow ice), we also identify several sites, including Zephyria Planum, as plausible locations for shallow subsurface equatorial water ice that is detectable by gamma-ray spectroscopy or neutron spectroscopy. In addition to confirming &lt;1.5 Gyr sedimentary rock formations on Mars, and distinguishing older and younger MFF sites, we find that fast-eroding locations have younger ages and MFF locations with slower erosion have older best-fit ages.

Keywords: Surface processes, Mars, Planetary surfaces
A Survey of CO, CO<SUB>2</SUB>, and H<SUB>2</SUB>O in Comets and Centaurs. CO and CO2 are the two dominant carbon-bearing molecules in comae and have major roles in driving activity. Their relative abundances also provide strong observational constraints to models of solar system formation and evolution but have never been studied together in a large sample of comets. We carefully compiled and analyzed published measurements of simultaneous CO and CO2 production rates for 25 comets. Approximately half of the comae have substantially more CO2 than CO, about one-third are CO-dominated, and about 1/10 produce a comparable amount of both. There may be a heliocentric dependence to this ratio with CO dominating comae beyond 3.5 au. Eight out of nine of the Jupiter Family Comets in our study produce more CO2 than CO. The six dynamically new comets produce more CO2 relative to CO than the eight Oort Cloud comets that have made multiple passes through the inner solar system. This may be explained by long-term cosmic-ray processing of a comet nucleus's outer layers. We find (Q CO/Q ${}_{{{\rm{H}}}_{2}{\rm{O}}}$ )median = 3 ± 1% and (Q ${}_{{\mathrm{CO}}_{2}}$ /Q ${}_{{{\rm{H}}}_{2}{\rm{O}}}$ )median = 12 ± 2%. The inorganic volatile carbon budget was estimated to be (Q CO+Q ${}_{{\mathrm{CO}}_{2}}$ )/Q ${}_{{{\rm{H}}}_{2}{\rm{O}}}$ ~ 18% for most comets. Between 0.7 and 4.6 au, CO2 outgassing appears to be more intimately tied to the water production in a way that the CO is not. The volatile carbon/oxygen ratio for 18 comets is C/Omedian ~ 13%, which is consistent with a comet formation environment that is well within the CO snow line.

Keywords: Comet origins, Comet dynamics, Carbon dioxide, Comae
Effects of Impact and Target Parameters on the Results of a Kinetic Impactor: Predictions for the Double Asteroid Redirection Test (DART) Mission. The Double Asteroid Redirection Test (DART) spacecraft will impact into the asteroid Dimorphos on 2022 September 26 as a test of the kinetic impactor technique for planetary defense. The efficiency of the deflection following a kinetic impactor can be represented using the momentum enhancement factor, β, which is dependent on factors such as impact geometry and the specific target material properties. Currently, very little is known about Dimorphos and its material properties, which introduces uncertainty in the results of the deflection efficiency observables, including crater formation, ejecta distribution, and β. The DART Impact Modeling Working Group (IWG) is responsible for using impact simulations to better understand the results of the DART impact. Pre-impact simulation studies also provide considerable insight into how different properties and impact scenarios affect momentum enhancement following a kinetic impact. This insight provides a basis for predicting the effects of the DART impact and the first understanding of how to interpret results following the encounter. Following the DART impact, the knowledge gained from these studies will inform the initial simulations that will recreate the impact conditions, including providing estimates for potential material properties of Dimorphos and β resulting from DART's impact. This paper summarizes, at a high level, what has been learned from the IWG simulations and experiments in preparation for the DART impact. While unknown, estimates for reasonable potential material properties of Dimorphos provide predictions for β of 1-5, depending on end-member cases in the strength regime.

Keywords: Impact phenomena, Asteroids, Planetary science
Numerical Simulations of Drainage Grooves in Response to Extensional Fracturing: Testing the Phobos Groove Formation Model. The long, shallow, parallel grooves that cut across the surface of the Martian moon Phobos remain enigmatic, with distinct implications for understanding the evolution of loose airless soils and the origin of Mars and its satellites. Phobos orbits deep inside the fluid Roche limit and is gradually spiraling in, creating global tidal strain, which leads to a model in which orbital decay is driving the formation of surface grooves on Phobos. Here we test this model by simulating the extension of a mildly cohesive regolith shell, driven by Phobos's tidal strain imposed by orbital migration. Modeling Phobos as a rubble-pile interior overlaid by a cohesive layer, we find that the tidal strain could create parallel fissures with regular spacing, depending on the latitude and longitude. Fracture opening triggers drainage of upper loose material into these deep-seated valleys, which we show could lead naturally to the formation of groove-like structures. We map the prominent linear depressions on Phobos and find that some at midlatitudes correlate with the model-predicted groove orientations. Our analysis supports a layered heterogeneous structure for Phobos with possible underlying failure-induced fractures, as the precursor of the eventual demise of the de-orbiting satellite. However, we do observe significant areas showing absences and anomalies that are not consistent with the tidal fracturing model. The in situ observations on Phobos by the Mars Moons eXploration mission will conclusively determine the origin of its enigmatic striations.

Keywords: Tidal distortion, Martian satellites, Small Solar System bodies, Natural satellite dynamics, Regolith
Jupiter's Banding and Jets May Be Caused by Tides. The stratification parameters for Jupiter's outer 3000 km shell are calculated using a density profile recently derived from observations of the NASA Juno spacecraft currently in Jovian orbit. Using these parameters, the equations of classical tidal theory for a stratified, nonhydrostatic, compressible fluid are numerically solved for sectoral tidal forcing by Io. The results support a long-standing though little discussed proposal that the banding/jets (and possibly the unexplained endogenic heat) are caused by the tides. First, general arguments from eigenmode analyses expect resonantly forced tidal modes and the scattering of the tidal response to higher spatial degrees by Jupiter's fast rotation, with time-averaged tidal effects appearing in bands between critical latitudes (±50° for forcing by Io). Second, resonant tides and banding are specifically demonstrated in the tidal model configured with the Juno-derived stratification. While banding in the time-averaged tidal features is a robust expectation (from the well-prescribed forcing and rotation parameters) and is independent of the internal parameters, the details of the banding (e.g., number, width) are highly dependent. Hence, comparison of the tidal model with observations provides a test of the tidal hypothesis of the bands as well as assumptions of interior parameters and processes. Here, dissipation parameterized as a simple pressure relaxation term in the vertical balance equation shows a time-mean banded structure between the critical latitudes that can drive geostrophic jets matching the major observed features, including strong prograde flow at the equator. By contrast, alternate stratification/dissipation assumptions produce banded structures that do not agree with observations.

Keywords: Hot Jupiters, Solar system gas giant planets, Jupiter, Atmospheric tides, Tides
29P/Schwassmann-Wachmann 1: A Rosetta Stone for Amorphous Water Ice and CO ↔ CO<SUB>2</SUB> Conversion in Centaurs and Comets?. Centaur 29P/Schwassmann-Wachmann 1 (SW1) is a highly active object orbiting in the transitional "Gateway" region between the Centaur and Jupiter-family comet (JFC) regions. SW1 is unique among the Centaurs in that it experiences quasi-regular major outbursts and produces CO emission continuously; however, the source of the CO is unclear. We argue that, due to its very large size (~32 km radius), SW1 is likely still responding, via amorphous water ice (AWI) conversion to crystalline water ice (CWI), to the "sudden" change in its external thermal environment produced by its Myrs-long dynamical migration from the Kuiper Belt to its current location at the inner edge of the Centaur region. It is this conversion process that is the source of the abundant CO and dust released from the object during its quiescent and outburst phases. If correct, these arguments have a number of important predictions testable via remote sensing and in situ spacecraft characterization, including the quick release on Myr timescales of CO from AWI conversion for any few kilometer-scale scattered disk Kuiper Belt Objects transiting into the inner system; that to date SW1 has only converted between 50% and 65% of its nuclear AWI to CWI; that volume changes on AWI conversion could have caused subsidence and cave-ins, but not significant mass wasting or crater loss; that SW1's coma should contain abundant amounts of CWI+CO2 "dust" particles; and that when SW1 transits into the inner system within the next 10,000 yr, it will be a very different kind of JFC.

Keywords: Centaur group, Ice formation, Comet nuclei, Comet surfaces, Surface ices, Comet volatiles , Comet interiors
The EXCITING Experiment Exploring the Behavior of Nitrogen and Noble Gases in Interstellar Ice Analogs. Comets represent some of the most pristine bodies in our solar system and can provide a unique insight into the chemical makeup of the early solar system. Due to their icy volatile-rich nature, they may have played an important role in delivering volatile elements and organic material to the early Earth. Understanding how comets form can therefore provide a wealth of information on how the composition of volatile elements evolved in the solar system from the presolar molecular cloud up until the formation of the terrestrial planets. Because noble gases are chemically inert and have distinct condensation temperatures, they can be used to infer the temperatures of formation and thermal history of cometary ices. In this work, we present a new experimental setup called EXCITING to investigate the origin and formation conditions of cometary ices. By trapping nitrogen and noble gases in amorphous water ice, our experiment is designed to study the elemental and isotopic behavior of volatile elements in cometary ice analogs. We report new results of noble gas and nitrogen enrichment in cometary ice analogs and discuss the limitations of the experimental conditions in light of those supposed for comets. We show that forming ice analogs at ~70 K best reproduce the noble gas and N2 abundances of comet 67P/Churyumov-Gerasimenko, considering a solar-like starting composition. This formation temperature is higher than previous estimates for cometary ices and suggests that the formation of cometary building blocks may have occurred in the protosolar nebula rather than in the colder molecular cloud.

Keywords: Comet origins, Comet volatiles
Miranda's Thick Regolith Indicates a Major Mantling Event from an Unknown Source. We investigated "muted" craters and scarps across Miranda's cratered terrain. The morphologies of the muted craters are most consistent with modification by regolith deposition instead of erosion or viscous relaxation. We used three techniques to estimate regolith thickness. (1) Analysis of muted crater depth-Diameter (d-D) ratios near the South Polar Terrain Chasma indicates that regolith mantling their floors ranges from 0.3 to 1.2 km thick. Because older craters may have collected more regolith than younger craters, the true thickness may be similar to the highest estimate. (2) Analysis of crater size-frequency distributions across the cratered terrain indicates a thickness of 1.0 ± 0.2 km. (3) Analysis of a central mound within Alonso Crater indicates a thickness of ${1.4}_{-0.4}^{+0.3}$ km near Verona Rupes and may represent an upper limit. These results indicate that Miranda has one of the thickest regoliths in the solar system, which has important implications for Miranda's interior thermal properties. Regolith appears to mantle some scarps within Arden but not Elsinore or Inverness, indicating that Arden may be the oldest corona, contrary to previous relative age estimates. In this scenario, the mantling event was ongoing during Arden's formation but before Elsinore or Inverness formed. We propose three possible sources for Miranda's thick regolith: (1) giant impact ejecta, (2) plume deposits, and (3) Uranian ring deposits. We favor the ring deposit hypothesis, which is consistent with the regolith's large spatial extent, substantial thickness, and Miranda's slightly spectrally blue color. Follow-up studies that rigorously investigate these scenarios are required.

Keywords: Uranian satellites, Planetary science, Regolith, Tectonics, Craters
Complementary Mass Spectral Analysis of Isomeric O-bearing Organic Compounds and Fragmentation Differences through Analog Techniques for Spaceborne Mass Spectrometers. Mass spectrometers on board spacecraft typically use either impact ionization or electron ionization (EI) as ion sources. Understanding the similarities and differences in the spectral signatures and fragmentation patterns produced by different techniques in mass spectrometry could elucidate the composition of organic compounds. Here we present a comparison between the mass spectra obtained through laser-induced liquid beam ion desorption (LILBID; proven to simulate the impact ionization mass spectra of ice grains) and EI mass spectra of pairs of low-mass, isomeric aldehydes and ketones. Our comparison confirms that EI produces more fragmentation of carbonyl compounds, particularly aldehydes, than LILBID. We find protonated molecular ions [M+H]+ in LILBID but molecular ions [M]+ in EI spectra. From the evaluated species, LILBID generally produces oxygen-carrying fragment ions (e.g., [CHO]+ and [C2H3O]+) in the mass ranges 26-30 and 39-44 u, while in EI, most ions in these ranges correspond to hydrocarbon fragments. The LILBID spectra additionally show mostly protonated oxygen-bearing fragments [CH3O]+ and [C2H5O]+ at m/z 31 and 45, less commonly observed in EI spectra. We observe a decrease in the relative intensities of cation fragment mass lines between m/z 26 and 33 and an increase between m/z 39 and 45, with an increasing carbon number for ketones and aldehydes with LILBID and EI, respectively. Our study provides a basis for complementary compositional analysis to identify the structural properties of organic species in a space environment using different spaceborne mass spectrometers (e.g., SUrface Dust Analyzer and MAss Spectrometer for Planetary EXploration) on board NASA's future Europa Clipper space mission.

Keywords: Mass spectrometry, Enceladus, Europa, Astrobiology, Planetary science
TESS Unveils the Full Phase Curve of WASP-19b. We present the detection and analysis of the full-orbit phase curve and secondary eclipse of the short-period transiting hot Jupiter system WASP-19b with a single joint fit to photometric data and resolve parameter degeneracy. We analyze data taken by the Transiting Exoplanet Survey Satellite (TESS) during sectors 9 and 36. We model the data with our five-component model: primary transit, secondary eclipse, ellipsoidal variations, thermal emission, and reflected light, which are jointly fit to extract the information from all parameters simultaneously. The amplitude of Doppler beaming was also estimated to be ~3 parts-per-million (ppm), but given the precision of the photometric data, we found that it was negligible and excluded it from the total phase curve model. We confidently report the secondary eclipse depth of ${494}_{-48}^{+59}$ ppm, the most accurate eclipse depth determined so far for WASP-19b, after cleaning the data from the instrumental systematic noise. According to the TESS bandpass, the day and nightside temperatures of WASP-19b are ${2245}_{-20}^{+19}K$ and ${1095}_{-21}^{+20}$ , respectively. In addition, we find that the region of maximum brightness is well aligned with the substellar point, implying that there is an inefficient heat distribution from the dayside to the nightside. Our derived ${A}_{g}={0.11}_{-0.03}^{+0.03}$ , suggesting that WASP-19b's geometric albedo is greater than the geometric albedos of most other hot Jupiters. Finally, the ellipsoidal variation signal amplitude we calculated agrees with theoretical expectations. Our comprehensive model with the approach of Markov Chain Monte Carlo shows the remedy of the degeneracy parameter in photometric data.

Keywords: Exoplanet astronomy, Exoplanet systems
A Subsurface Magma Ocean on Io: Exploring the Steady State of Partially Molten Planetary Bodies. Intense tidal heating within Io produces active volcanism on the surface, and its internal structure has long been a subject of debate. A recent reanalysis of the Galileo magnetometer data suggested the presence of a high-melt-fraction layer with &gt;50 km thickness in the subsurface region of Io. Whether this layer is a "magmatic sponge" with interconnected solid or a rheologically liquid "magma ocean" would alter the distribution of tidal heating and would also influence the interpretation of various observations. To this end, we explore the steady state of a magmatic sponge and estimate the amount of internal heating necessary to sustain such a layer with a high degree of melting. Our results show that the rate of tidal dissipation within Io is insufficient to sustain a partial-melt layer of ϕ &gt; 0.2 for a wide range of parameters, suggesting that such a layer would swiftly separate into two phases. Unless melt and/or solid viscosities are at the higher end of the estimated range, a magmatic sponge would be unstable, and thus a high-melt-fraction layer suggested in Khurana et al. is likely to be a subsurface magma ocean.

Keywords: Io, Galilean satellites, Planetary interior
Semi-analytical Near-Earth Objects Propagation: The Orbit History of (35107) 1991 VH and (175706) 1996 FG3. The propagation of small bodies in the solar system is driven by the combination of planetary encounters that cause abrupt changes in their orbits and secular long-term perturbations. We propose a propagation strategy that combines both of these effects into a single framework for long-term, rapid propagation of small bodies in the inner solar system. The analytical secular perturbation of Jupiter is interrupted to numerically solve planetary encounters, which last a small fraction of the simulation time. The proposed propagation method is compared to numerical integrations in the solar system, effectively capturing properties of the numerical solutions in a fraction of the computational time. We study the orbital history of the Janus mission targets, (35107) 1991 VH and (175706) 1996 FG3, obtaining a stochastic representation of their long-term dynamics and frequencies of very close encounters. Over the past million years the probability of a strongly perturbing flyby is found to be small.

Keywords: Astrodynamics, Near-Earth objects, Asteroids, Asteroid dynamics, Close encounters, Opik theory, Flyby missions