Sazuna/UAT_keywords huggingface dataset:
The Second International Asteroid Warning Network Timing Campaign: 2005 LW3. The Earth close approach of near-Earth asteroid 2005 LW3 on 2022 November 23 represented a good opportunity for a second observing campaign to test the timing accuracy of astrometric observation. With 82 participating stations, the International Asteroid Warning Network collected 1046 observations of 2005 LW3 around the time of the close approach. Compared to the previous timing campaign targeting 2019 XS, some individual observers were able to significantly improve the accuracy of their reported observation times. In particular, U.S. surveys achieved good timing performance. However, no broad, systematic improvement was achieved compared to the previous campaign, with an overall negative bias persisting among the different observers. The calibration of observing times and the mitigation of timing errors should be important future considerations for observers and orbit computers, respectively.

Keywords: Near-Earth objects, Astrometry, Optical telescopes, Asteroids
Constraining the Structure under Lunar Impact Basins with Gravity. The lunar gravity field is used to estimate and constrain the depth of mass anomalies under 19 major lunar impact basins. We use radial gravitational spectra, consisting of accelerations computed either per spherical harmonic degree or cumulatively, at surface locations to obtain the distribution of the gravity signal with spherical harmonic degree and, by implication, to the likely depth below the surface. The results provide estimates for the maximum likely depths of the primary component to the mass anomalies under 19 basins. We find that the maximum depths of the primary source of mascon gravity on the lunar nearside are deeper than the depths for those on the farside when South Pole-Aitken (SPA) is excluded. All basin mass anomalies on the lunar nearside are in the mantle. The maximum depth of the primary source of the mass anomalies is &lt;80 km, with the exception of SPA, whose dominant mass signature lies at a maximum depth of &gt;200 km beneath the surface. The upper 20 km under all basins is largely devoid of anomalies, reflecting predominantly mixing and relaxation associated with impact melt combined with ejecta fallback, as well as homogenization associated with post-basin formation impact bombardment. Except for SPA, all basin anomalies merge with the deep interior at ~150 km or below, indicating the depth penetration of disruption of the density structure of the lunar interior associated with impact bombardment.

Keywords: Lunar gravitational field
Infrared Spectra and Vapor Pressures of Crystalline C<SUB>2</SUB>N<SUB>2</SUB>, with Comparisons to Crystalline HCN. In a continuation of our work on nitriles, we have examined cyanogen (C2N2) as a crystalline solid, comparing the results to our recent work on crystalline hydrogen cyanide (HCN). A density and refractive index for C2N2 ice were measured and used to prepare solid samples from which infrared (IR) spectra, band strengths, and optical constants were measured. The vapor pressures (sublimation pressures) of both C2N2 and HCN ices were determined with a quartz-crystal microbalance at temperatures relevant to Titan's atmosphere and much lower than those in the literature. Comparisons of the newly measured low-temperature vapor pressures to values extrapolated from higher temperatures revealed differences on the order of 45 and 130%. The enthalpies of sublimation of C2N2 and HCN in the 120 K region were measured and found to be similar to those at higher temperatures. Comparisons were made to previous spectroscopic work, but hindered in the case of IR intensities by the lack of published details.

Keywords: Experimental techniques, Titan, Astrochemistry
ALMA Observations of the DART Impact: Characterizing the Ejecta at Submillimeter Wavelengths. We report observations of the Didymos-Dimorphos binary asteroid system using the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Compact Array (ACA) in support of the Double Asteroid Redirection Test mission. Our observations on UT 2022 September 15 provided a preimpact baseline and the first measure of Didymos-Dimorphos's spectral emissivity at λ = 0.87 mm, which was consistent with the handful of siliceous and carbonaceous asteroids measured at millimeter wavelengths. Our postimpact observations were conducted using four consecutive executions each of ALMA and the ACA spanning from T+3.52 to T+8.60 hr, sampling thermal emission from the asteroids and the impact ejecta. We scaled our preimpact baseline measurement and subtracted it from the postimpact observations to isolate the flux density of millimeter-sized grains in the ejecta. Ejecta dust masses were calculated for a range of materials that may be representative of Dimorphos's S-type asteroid material. The average ejecta mass over our observations is consistent with 1.3-6.4 × 107 kg, with the lower and higher values calculated for amorphous and crystalline silicates, respectively. Owing to the likely crystalline nature of S-type asteroid material, the higher value is favored. These ejecta masses represent 0.3%-1.5% of Dimorphos's total mass and are in agreement with lower limits on the ejecta mass based on measurements at optical wavelengths. Our results provide the most sensitive measure of millimeter-sized material in the ejecta and demonstrate the power of ALMA for providing supporting observations to spaceflight missions.

Keywords: High resolution spectroscopy, Near-Earth objects, Impact phenomena, Asteroids, Radio interferometry, Radio astronomy
A WISPR of the Venus Surface: Analysis of the Venus Nightside Thermal Emission at Optical Wavelengths. Parker Solar Probe (PSP) conducted several flybys of Venus while using Venus' gravity for orbital adjustments to enable its daring passes of the Sun. During these flybys, PSP turned to image the nightside of Venus using the Wide-field Imager for Solar PRobe (WISPR) optical telescopes, which unexpectedly observed Venus' surface through its thick and cloudy atmosphere in a theorized, but until-then unobserved near-visible spectral window below 0.8 μm. We use observations taken during PSP's fourth Venus gravity assist flyby to examine the origin of the Venus nightside flux and confirm the presence of this new atmospheric window through which to observe the surface geology of Venus. The WISPR images are well explained by emission from the hot Venus surface escaping through a new atmospheric window in the optical with an overlying emission component from the atmosphere at the limb that is consistent with O2 nightglow. The surface thermal emission correlates strongly with surface elevation (via temperature) and emission angle. Tessera and plains units have distinct WISPR brightness values. Controlling for elevation, Ovda Regio tessera is brighter than Thetis Regio; likewise, the volcanic plains of Sogolon Planitia are brighter than the surrounding regional plains units. WISPR brightness at 0.8 μm is predicted to be positively correlated to FeO content in minerals; thus, the brighter units may have a different starting composition, be less weathered, or have larger particle sizes.

Keywords: Planetary surfaces, Surface composition, Venus, Planetary atmospheres, Solar optical telescopes, Planetary science, Planetary geology, Solar instruments, Solar system astronomy
First Detection of CO<SUB>2</SUB> Emission in a Centaur: JWST NIRSpec Observations of 39P/Oterma. Centaurs are minor solar system bodies with orbits transitioning between those of trans-Neptunian scattered disk objects and Jupiter-family comets (JFCs). 39P/Oterma (39P) is a frequently active centaur that has recently held both centaur and JFC classifications and was observed with the JWST NIRSpec instrument on 2022 July 27 UTC while it was 5.82 au from the Sun. For the first time, CO2 gas emission was detected in a centaur, with a production rate of ${Q}_{{\mathrm{CO}}_{2}}$ = (5.96 ± 0.80) × 1023 molecules s-1. This is the lowest detection of CO2 of any centaur or comet. CO and H2O were not detected down to constraining upper limits. Derived mixing ratios of Q CO/Q ${}_{{\mathrm{CO}}_{2}}$ ≤ 2.03 and ${Q}_{{\mathrm{CO}}_{2}}$ /Q ${}_{{{\rm{H}}}_{2}{\rm{O}}}$ ≥ 0.60 are consistent with CO2 and/or CO outgassing playing large roles in driving the activity, but not water, and show a significant difference between the coma abundances of 29P/Schwassmann-Wachmann 1, another centaur at a similar heliocentric distance, which may be explained by thermal processing of 39P's surface during its previous JFC orbit. To help contextualize the JWST data we also acquired visible CCD imaging data on two dates in 2022 July (Gemini-North) and September (Lowell Discovery Telescope). Image analysis and photometry based on these data are consistent with a point-source detection and an estimated effective nucleus radius of 39P in the range of R nuc = 2.21-2.49 km.

Keywords: Centaur group, Carbon dioxide, James Webb Space Telescope, Infrared observatories, Comets
Radar Perspective of the Aristarchus Pyroclastic Deposit and Implications for Future Missions. The Aristarchus plateau represents one of the most complex volcanic provinces on the lunar surface and is host to the largest pyroclastic deposit on the Moon. Lunar pyroclastic deposits offer a window into the Moon's interior and represent a valuable resource to support a sustained human presence. We present a new analysis of the Aristarchus pyroclastic deposit using Mini-RF bistatic radar data at wavelengths of 4.2 and 12.6 cm. Building on previous Earth-based Arecibo Observatory radar studies at 12.6 and 70 cm, we place further constraints on the spatial extent of the pyroclastic deposit and investigate the clast size distribution and provenance of foreign material distributed within the formation. Concentrations of blocky material &gt;0.5 cm in diameter and suspended within the upper decimeters of the pyroclastic deposit are associated with potential buried mare flows along the rim of Vallis Schröteri and discrete pockets of primary material ejected by the Aristarchus impact. Unraveling the deposit from nonpyroclastic materials and the surrounding landscape creates new constraints with which to reconstruct the volcanic history of the region. From a future mission perspective, the identification of primary Aristarchus material distributed across the plateau offers an opportunity to sample diverse volcanic lithologies within an area that could be sampled by a single Commercial Lunar Payload Services mission. In terms of lunar resource in situ utilization, such ejected material also represents a contaminant; thus, radar data provide an invaluable tool to identify pristine pyroclastic material for mission planners.

Keywords: Lunar maria, The Moon, Radar astronomy, Volcanism
The Control of Lava Rheology on the Formation of Lunar Sinuous Rilles by Substrate Thermal Erosion: Topographic and Morphometric Relationships with Eruption Rates, Erosion Rates, Event Durations, and Erupted Magma Volumes. We describe a model of the fluid mechanics and thermodynamics of turbulent lava flows capable of thermally eroding sinuous rille channels on bodies without atmospheres. The model assumes Bingham plastic rheology for the lava and shows how the effects of radiant cooling and consequent crystallization change the rheology and control the point at which turbulence ceases. A correlation is found between magma volume eruption rate and the length and width of the eroded rille channel. Thus, simple measurements of rille length and width in images can provide reliable estimates of magma eruption rates. The model also predicts rille floor erosion rates, so that if rille depths are measured, eruption durations and erupted magma volumes can also be found. The model is applied in detail to six well-preserved lunar rilles and more generally to a published catalog of 214 lunar rilles. We find that rille-forming eruptions have magma volume eruption rates of a few times 104 m3 s-1, durations of up to 3 months, and erupted magma volumes up to ~200 km3, consistent with theoretical predictions of basaltic magma ascent and eruption from deep mantle sources. The key requirement for rille formation, rather than mare lava flow deposit formation, is the turbulent eruption of a sufficiently large volume of low-viscosity magma at a sufficiently low eruption rate.

Keywords: Planetary surfaces
Titania's Heat Fluxes Revealed by Messina Chasmata. Messina Chasmata is a relatively young tectonic structure on Titania based on cross-cutting relationships, although an absolute age has not been estimated. We investigated lithospheric flexure bounding Messina and found that the terrain along both rims reflects Titania's thermal properties. We estimate Titania's heat fluxes to have been 5-12 mW m-2 in this region, assuming that the lithosphere is composed of pure H2O ice without porosity. These estimates are lower if lithospheric porosity and/or NH3-H2O are also present. If Messina is ancient, forming as a result of freeze expansion, then the reflected heat fluxes are consistent with radiogenic heating. However, if Messina is instead young, then an additional heat source is required. In this scenario, perhaps tidal heating associated with the past three-body resonance shared between Titania, Ariel, and Umbriel generated this heat. However, this scenario is unlikely because the amount of tidal heating produced on Titania would have been minimal. Titania's heat fluxes are notably lower than estimates for Miranda or Ariel, and future work is needed to investigate Umbriel and Oberon to gain a fuller understanding of Uranian moon thermal and orbital histories. Additionally, further constraints on Titania's more ancient heat fluxes could be obtained by investigating relatively older features, such as some viscously relaxed impact craters.

Keywords: Uranian satellites, Natural satellite surfaces, Natural satellites (Solar system), Planetary science, Tectonics
The Search for Topographic Correlations within the Reiner Gamma Swirl. Lunar swirls have been traditionally considered to be unaffected by topographic changes. Yet, correlations between areas of high albedo and lower elevations are observed in regions of the Mare Ingenii swirl. Here, we apply similar techniques used at Mare Ingenii to determine if correlations between swirl units and topography also exist within Reiner Gamma. We generate topography using the techniques of stereophotoclinometry to Lunar Reconnaissance Orbiter Camera Narrow Angle Camera images to derive meter- to submeter-scale topography. We choose a 50 km2 study region with a 2.6 m ground sample distance (GSD), and within this region there is a 1 km2 subregion with a 0.8 m GSD. We use surface reflectance data at multiple viewing geometries to classify these regions into different swirl units using machine learning techniques. Statistical analyses of the data show mean height variations between on- and off-swirl of ~4 m, with on-swirl at a lower elevation. It is not clear how this scale of elevation difference influences the formation of swirl units, but it supports postulations of dust migration and magnetic sorting contributing to their formation.

Keywords: Lunar regolith, Solar system planets, Surface processes, The Moon, Solar system terrestrial planets, Lunar surface, Planetary science, Lunar features, Albedo
The Importance of Isentropic Mixing in the Formation of the Martian Polar Layered Deposits. Layers of ice and dust at the poles of Mars reflect variations in orbital parameters and atmospheric processes throughout the planet's history and may provide a key to understanding Mars's climate record. Previous research has investigated transport changes into the polar regions and found a nonlinear response to obliquity that suggests that Mars may currently be experiencing a maximum in transport across the winter poles. The thickness and composition of layers within the polar layered deposits (PLDs) are likely influenced by changes in horizontal atmospheric mixing at the poles, which is an important component of the transport of aerosols and chemical tracers. No study has yet investigated horizontal mixing alone, which may be influenced by polar vortex morphology. We show that mixing in an idealized Martian global climate model varies significantly with obliquity and dust abundance by using a diagnostic called effective diffusivity, which has been used to study the stratospheric polar vortices on Earth and to understand their role as a mixing barrier but has not been applied to Mars's polar vortices. We find that mixing in the winter southern hemisphere doubles with either an octupling of dust loading or an increase in obliquity from 10° to 50°. We find a weaker response to changing dust loading or obliquity in the northern hemisphere. We demonstrate that horizontal mixing is an important component of transport into Mars's polar regions, may contribute to the formation of the PLDs, and presents effective diffusivity as a useful method to understand mixing in the Martian atmosphere.

Keywords: Mars, Atmospheric dynamics, Planetary atmospheres, Atmospheric circulation
Near to Mid-infrared Spectroscopy of (65803) Didymos as Observed by JWST: Characterization Observations Supporting the Double Asteroid Redirection Test. The Didymos binary asteroid was the target of the Double Asteroid Redirection Test (DART) mission, which intentionally impacted Dimorphos, the smaller member of the binary system. We used the Near-Infrared Spectrograph and Mid-Infrared Instrument instruments on JWST to measure the 0.6-5 and 5-20 μm spectra of Didymos approximately two months after the DART impact. These observations confirm that Didymos belongs to the S asteroid class and is most consistent with LL chondrite composition, as was previously determined from its 0.6-2.5 μm reflectance spectrum. Measurements at wavelengths &gt;2.5 μm show Didymos to have thermal properties typical for an S-complex asteroid of its size and to be lacking absorptions deeper than ~2% due to OH or H2O. Didymos' mid-infrared emissivity spectrum is within the range of what has been measured on S-complex asteroids observed with the Spitzer Space Telescope and is most consistent with emission from small (&lt;25 μm) surface particles. We conclude that the observed reflectance and physical properties make the Didymos system a good proxy for the type of ordinary chondrite asteroids that cross near-Earth space, and a good representative of likely future impactors.

Keywords: Asteroid satellites, Asteroids, Infrared spectroscopy, Spectroscopy
Detectability of the Yarkovsky Effect in the Main Belt. We attempt to detect a signal of Yarkovsky-related acceleration in the orbits of 134 main belt asteroids (MBAs) we observed with the University of Hawai'i 88 inch telescope, supplemented with observations publicly available from the Minor Planet Center and Gaia Data Release 3. We estimated the expected Yarkovsky acceleration values based on parameters derived through thermophysical modeling, but we were not able to find any reliable detections of Yarkovsky in our sample. Through tests with synthetic observations, however, we estimated the minimum observational arc length needed to detect the Yarkovsky effect for all of our sample MBAs, which in nearly every case exceeded the current arc length of the existing observations. We find that the Yarkovsky effect could be detectable within a couple of decades of discovery for a 100 m MBA assuming 0.″1 astrometric accuracy, which is at the size range detectable by the upcoming Vera Rubin Observatory Legacy Survey of Space and Time.

Keywords: Main belt asteroids, Orbit determination
Dynamical Interactions and Mass Loss within the Uranian System. The origin and evolution of planetary rings and moons remains an active area of study, particularly as they relate to the impact history and volatile inventory of the outer solar system. The Uranian system contains a complex system of rings that are coplanar with the highly inclined planetary equator relative to the orbital plane. Uranus also harbors five primary regular moons that play an important role in the distribution of material that surrounds the planet. Here we present the results of a dynamical simulation suite for the Uranian system, intended to explore the interaction between the five primary regular moons and particles within the system. We identify regions of extreme mass loss within 40 planetary radii of Uranus, including eccentricity excitation of particle orbits at resonance locations that can promote moonlet formation within the rings. We calculate a total dynamical particle mass-loss rate of 35% within 0.5 × 106 yr and 40% mass loss within 107 yr. We discuss the implications for postimpact material, including dynamical truncation of stable ring locations and/or locations of moon formation promoted by dynamical excitation of ring material.

Keywords: Uranian satellites, Solar system planets, Orbits, Dynamical evolution, Orbital resonances, Orbital evolution, Planetary rings, Solar system, Uranus
Physical Characterization of Moon Impactor WE0913A. On 2022 March 4, the object known as WE0913A crashed into the Moon after several close flybys of the Earth and the Moon in the previous three months. Leading up to impact, the identity of the lunar impactor was up for debate, with two possibilities: the Falcon 9 from the DSCOVR mission or the Long March 3C from the Chang'e 5-T1 mission. In this paper, we present a trajectory and spectroscopic analysis using ground-based telescope observations to show conclusively that WE0913A is the Long March 3C rocket body (R/B) from the Chang'e 5-T1 mission. Analysis of photometric light curves collected before impact give a spin period of 185.221 ± 6.540 s before the first close Earth flyby on 2022 January 20 and a period of 177.754 ± 0.779 s, both at a 1σ confidence level, before the second close Earth flyby on 2022 February 8. Using Markov Chain Monte Carlo sampling and a predictive light curve simulation based on an anisotropic Phong reflection model, we estimate both physical and dynamical properties of the Chang'e 5-T1 R/B at the start of an observation epoch. The results from the Bayesian analysis imply that there may have been additional mass on the front of the rocket body. Using our predicted impact location, the Lunar Reconnaissance Orbiter was able to image the crater site approximately 7.5 km from the prediction. Comparing the pre- and post-impact images of the location shows two distinct craters that were made, supporting the hypothesis that there was additional mass on the rocket body.

Keywords: Lunar impacts, Bayesian statistics, Astrometry, Orbit determination
Global Hall MHD Simulations of the Solar Wind Implantation Flux on the Lunar Surface. The solar wind can directly interact with the lunar surface and provide an important source for surface space weathering and water generation. Here we study the solar wind implantation flux on the lunar surface with global Hall MHD simulations. The shielding effects of both the Earth's magnetosphere and lunar magnetic anomalies are considered. It is found that a large-scale lunar mini-magnetosphere can be caused by the solar wind interaction with the magnetic anomalies on the lunar far side, which causes a large shielding area on the surface. In addition, the Earth's magnetosphere brings a longitudinal variation in the implantation flux, with minimum fluxes at 0° longitude. With the integrated flux over a lunation, we find that there are some local cavities on the implantation flux map, which are colocated with both the magnetic anomalies and the lunar swirls. Further studies show that there is a south-north asymmetry in the implantation flux, which can be used to explain the lower water content observed in the southern hemisphere. Our results provide a global map of the solar wind implantation flux on the lunar surface and are useful for evaluating the large-scale effect of solar wind implantation and sputtering on the space weathering and the water or gas generation of the surface.

Keywords: Space plasmas, Solar wind, Solar-planetary interactions, Lunar science