Sazuna/UAT_keywords huggingface dataset:
Stereophotoclinometry on the OSIRIS-REx Mission: Mathematics and Methods. Stereophotoclinometry (SPC) makes it possible to extract the shapes of surfaces by combining information from images, namely stereo parallax data and surface shading from slopes, with knowledge of the location of a spacecraft. This technique has been used extensively in the past few decades to describe the shapes of planets and small bodies, such as asteroids and comets. It has also been used to carefully navigate spacecraft around very small bodies, as in the case of the OSIRIS-REx mission to the ~500 m diameter asteroid (101955) Bennu. This paper describes the mathematical foundation of SPC, with examples from the OSIRIS-REx mission.

Keywords: Photogrammetry, Asteroids
Thermal Models of Asteroids with Two-band Combinations of Wide-field Infrared Survey Explorer Cryogenic Data. We used the reparameterized Near-Earth Asteroid Thermal Model to model observations of a curated set of over 4000 asteroids from the Wide-field Infrared Survey Explorer in two wavelength bands (W2-3 or W3-4) and compared the results to previous results from all four wavelength bands (W1-4). This comparison was done with the goal of elucidating unique aspects of modeling two-band observations so that any potential biases or shortcomings for planned two-band surveys (e.g., the NASA Near-Earth Object Surveyor Mission) can be anticipated and quantified. The W2-3 two-band fits usually yielded slightly smaller diameters than the four-band fits, with a median diameter difference of -10%, with the 5% and 95% quantiles of the distribution at -32% and -1.5%, respectively. We conducted similar comparisons for W3-4, in part because the longest wavelength bands are expected to provide the best two-band results. We found that the W3-4 two-band diameters are slightly larger than the four-band results, with a median diameter difference of 11% and the 5% and 95% quantiles of the distribution at -2.1% and 26%, respectively. The diameter uncertainty, obtained with bootstrap analysis, is larger by 30% and 35% (median values) for the W2-3 and W3-4 fits, respectively, than for the corresponding four-band fits. Using 23 high-quality stellar occultation diameters as a benchmark, we found that the median errors of W2-3 and W3-4 diameter estimates are -15% and +12%, respectively, whereas the median error of the four-band fits is 9.3%. Although the W2-3 and W3-4 diameters appear to have greater systematic errors and uncertainties than their four-band counterparts, two-band estimates remain useful because they improve upon diameter estimates obtained from visible photometry alone.

Keywords: Near-Earth objects, Sky surveys, Small Solar System bodies, Asteroids, Main belt asteroids
Constraining the Venus Interior Structure with Future VERITAS Measurements of the Gravitational Atmospheric Loading. The complex dynamics of the Venus atmosphere produces a periodic mass redistribution pattern that creates a time-variable modulation of the gravity field of Venus. This gravity signal depends on the net transport of mass across the globe and on the response of the solid body to the normal loading of its crust imparted by the atmosphere. In this work, we explore the possibility of measuring this phenomenon with VERITAS, a NASA Discovery-class mission. By simulating the gravity science experiment, we explore the possibility of measuring the response of Venus to the atmospheric loading, parametrized by the loading Love numbers ( ${k}_{l}^{{\prime} }$ ), and assess the dependence of these parameters on fundamental interior structure properties. Using the most recent models of Venus' interior, we compute the Venus Love numbers in a compressible viscoelastic setting and compare them with the predicted uncertainty of the VERITAS measurements. We show that VERITAS will measure ${k}_{2}^{{\prime} }$ at the 4% level and that this measurement could possibly help to distinguish between different equally plausible interior structure models, especially allowing us to distinguish different rheological laws. We also show that a measurement campaign such as the VERITAS gravity science investigation has the potential of measuring ${k}_{2}^{{\prime} }$ not only at the loading forcing frequency, but also at the tidal frequency, ultimately providing a way to probe the response of the planet at different forcing periods.

Keywords: Venus, Planetary probes, Atmospheric tides, Planetary science, Planetary dynamics, Planetary interior, Orbit determination
Can the Gravitational Effect of Planet X be Detected in Current-era Tracking of the Known Major and Minor Planets?. Using Fisher information matrices, we forecast the uncertainties σ  M  on the measurement of a "Planet X" at heliocentric distance d  X  via its tidal gravitational field's action on the known planets. Using planetary measurements currently in hand, including ranging from the Juno, Cassini, and Mars-orbiting spacecraft, we forecast a median uncertainty (over all sky positions) of ${\sigma }_{M}=0.22\,{M}_{\oplus }{({d}_{x}/400{\rm{au}})}^{3}.$ A 5σ detection of a 5 M ⊕ Planet X at d  X  = 400 au should be possible over the full sky but over only 5% of the sky at d  X  = 800 au. The gravity of an undiscovered Earth- or Mars-mass object should be detectable over 90% of the sky to a distance of 260 or 120 au, respectively. Upcoming Mars ranging improves these limits only slightly. We also investigate the power of high-precision astrometry of ≈8000 Jovian Trojans over the 2023-2035 period from the upcoming Legacy Survey of Space and Time (LSST). We find that the dominant systematic errors in optical Trojan astrometry (photocenter motion, nongravitational forces, and differential chromatic refraction) can be solved internally with minimal loss of information. The Trojan data allow cross-checks with Juno/Cassini/Mars ranging, but do not significantly improve the best achievable σ  M  values until they are ≳10× more accurate than expected from LSST. The ultimate limiting factor in searches for a Planet X tidal field is confusion with the tidal field created by the fluctuating quadrupole moment of the Kuiper Belt as its members orbit. This background will not, however, become the dominant source of uncertainty until the data get substantially better than they are today.

Keywords: Kuiper belt, Fisher's Information, Gravitation, Astrometry, Trans-Neptunian objects, Planetary dynamics
Establishing a Best Practice for SDTrimSP Simulations of Solar Wind Ion Sputtering. Solar wind (SW) ion irradiation on airless bodies can play an important role in altering their surface properties and surrounding exosphere. Much of the ion sputtering data needed for exosphere studies come from binary collision approximation sputtering models such as TRansport of Ions in Matter and its more recent extension, SDTrimSP. These models predict the yield and energy distribution of sputtered atoms, along with the depth of deposition and damage of the substrate, all as a function of the incoming ion type, impact energy, and impact angle. Within SDTrimSP there are several user-specific inputs that have been applied differently in previous SW ion sputtering simulations. These parameters can influence the simulated behavior of both the target and sputtered atoms. Here, we have conducted a sensitivity study into the SDTrimSP parameters in order to determine a best practice for simulating SW ion impacts onto planetary surfaces. We demonstrate that ion sputtering behavior is highly sensitive to several important input parameters including the ion impact angle and energy distribution and the ejected atom surface binding energy. Furthermore, different parameters can still result in similarities in the total sputtering yield, potentially masking large differences in other sputtering-induced behaviors such as the elemental yield, surface concentration, and damage production. Therefore, it is important to consider more than just the overall sputtering behavior when quantifying the importance of different parameters. This study serves to establish a more consistent methodology for simulations of SW-induced ion sputtering on bodies such as Mercury and the Moon, allowing for more accurate comparisons between studies.

Keywords: Theoretical techniques, Theoretical models, Planetary surfaces, Exosphere, Solid matter physics, Space weather, The Moon, Solar wind, Laboratory astrophysics, Collision physics, Mercury (planet)
Traveling Planetary-scale Waves Cause Cloud Variability on Tidally Locked Aquaplanets. Cloud cover at the planetary limb of water-rich Earth-like planets is likely to weaken chemical signatures in transmission spectra, impeding attempts to characterize these atmospheres. However, based on observations of Earth and Solar System worlds, exoplanets with atmospheres should have both short-term weather and long-term climate variability, implying that cloud cover may be less during some observing periods. We identify and describe a mechanism driving periodic clear sky events at the terminators in simulations of tidally locked Earth-like planets. A feedback between dayside cloud-radiative effects, incoming stellar radiation and heating, and the dynamical state of the atmosphere, especially the zonal wavenumber 1 Rossby wave identified in past work on tidally locked planets, leads to oscillations in Rossby wave phase speeds and in the position of Rossby gyres, and this results in advection of clouds to or away from the planet's eastern terminator. We study this oscillation in simulations of Proxima Centauri b, TRAPPIST-1e, and rapidly rotating versions of these worlds located at the inner edge of their stars' habitable zones. We simulate time series of the transit depths of the 1.4 μm water feature and 2.7 μm carbon dioxide feature. The impact of atmospheric variability on the transmission spectra is sensitive to the structure of the dayside cloud cover and the location of the Rossby gyres, but none of our simulations have variability significant enough to be detectable with current methods.

Keywords: Exoplanet atmospheric dynamics, Exoplanet atmospheres, Exoplanet atmospheric variability, Exoplanets
ASSIST: An Ephemeris-quality Test-particle Integrator. We introduce ASSIST, a software package for ephemeris-quality integrations of test particles. ASSIST is an extension of the REBOUND framework and makes use of its IAS15 integrator to integrate test-particle trajectories in the field of the Sun, Moon, planets, and 16 massive asteroids, with the positions of the masses coming from the Jet Propulsion Laboratory's DE441 ephemeris and its associated asteroid perturber file. The package incorporates the most significant gravitational harmonics and general-relativistic corrections. ASSIST also accounts for position- and velocity-dependent nongravitational effects. The first-order variational equations are included for all terms to support orbit fitting and covariance mapping. This new framework is meant to provide an open-source package written in a modern language to enable high-precision orbital analysis and science by the small-body community. ASSIST is open source, freely distributed under the GNU General Public license v3.0.

Keywords: Ephemerides, Comet dynamics, N-body simulations, Asteroid dynamics
Sodium Brightening of (3200) Phaethon near Perihelion. Sunskirting asteroid (3200) Phaethon has been repeatedly observed in Solar Terrestrial Relations Observatory (STEREO) Heliospheric Imager 1 (HI1) imagery to anomalously brighten and produce an antisunward tail for a few days near each perihelion passage, phenomena previously attributed to the ejection of micron-sized dust grains. Color imaging by the Solar and Heliospheric Observatory (SOHO) Large Angle Spectrometric Coronagraph (LASCO) during the 2022 May apparition indicates that the observed brightening and tail development instead capture the release of sodium atoms, which resonantly fluoresce at the 589.0/589.6 nm D lines. While HI1's design bandpass nominally excludes the D lines, filter degradation has substantially increased its D line sensitivity, as quantified by the brightness of Mercury's sodium tail in HI1 imagery. Furthermore, the expected fluorescence efficiency and acceleration of sodium atoms under solar radiation readily reproduce both the photometric and morphological behaviors observed by LASCO and HI1 during the 2022 apparition and the 17 earlier apparitions since 1997. This finding connects Phaethon to the broader population of sunskirting and sungrazing comets observed by SOHO, which often also exhibit bright sodium emission with minimal visible dust, but distinguishes it from other sunskirting asteroids without detectable sodium production under comparable solar heating. These differences may reflect variations in the degree of sodium depletion of near-surface material and thus the extent and/or timing of any past or present resurfacing activity.

Keywords: Near-Earth objects, Comet tails, Sunskirters, Comet origins, Comet volatiles , Sungrazers, Asteroid surfaces
Approaches for Retrieving Sulfur Species Abundances from Dual X-Ka-band Radio Occultations of Venus with EnVision and VERITAS. The EnVision and VERITAS missions to Venus will fly with X- and Ka-band telecommunications channels, which can be used to conduct radio occultation studies of Venus' atmosphere. While link attenuation measurements during prior S- and X-band occultation experiments have been used to determine vertical profiles of H2SO4 vapor abundance, the addition of the Ka-band channel introduces greater sensitivity to the abundances of H2SO4 aerosols and SO2 gas, permitting the retrieval of their vertical profiles from dual-band measurements. Such measurements would be valuable in the assessment of chemical and dynamical processes governing short- and long-term variability in Venus' atmosphere. This paper considers the sensitivity of the X-Ka-band radio attenuation measurement to these atmospheric constituents, as well as uncertainties and regularization approaches for conducting retrievals of these atmospheric sulfur species from future occultation experiments. We introduce methods for seeding maximum likelihood estimation retrievals using shape models and simple atmospheric transport constraints. From simulated retrievals, we obtain mean errors of the order of 0.5 ppm, 20 ppm, and 10 mg m-3 for H2SO4 vapor, SO2, and H2SO4 aerosol abundances, respectively, for simultaneous retrieval.

Keywords: Planetary atmospheres, Radio occultation, Venus
Simulation of Space Weathering on Asteroid Spectra through Hydrogen Ion Irradiation of Meteorites. Space weathering can be defined as the combination of physical and chemical changes that occur in material exposed to an interplanetary environment on the surface of airless bodies. This process results in alterations in material spectroscopic features. Eventually, it can lead to misinterpretation of remotely sensed data in the visible-near-infrared wavelength range. This study simulates the solar wind effect on asteroid spectra through low-energy 1 keV H+ irradiation of meteorite pressed-powder samples under three fluences, 2 × 1017, 5 × 1017, and 1 × 1018 H+ cm-2, and evaluates changes associated with reflectance spectra. The meteorites subjected to the study are Bjurböle (L/LL4), Avanhandava (H4), and Luotolax (howardite). The most prominent changes in all three meteorites are (1) a decrease of 550 nm reflectance, (2) reddening in the 1 μm region, and (3) a monotonous decrease in absorption band strengths in Bjurböle. No significant changes were observed in the 2 μm region. The results imply that at short timescales (102-103 yr), radiation damage as amorphization and vesicle formation caused by low-energy solar wind is the dominant space weathering factor in all three meteorite compositions, causing spectral changes predominantly in the 1 μm region.

Keywords: Meteorites, Solar wind, Chondrites, Achondrites
The Evolution of Activity and Chemical Composition in Rosetta's Comet Targets across Multiple Apparitions: Complications for CS<SUB>2</SUB> as the CS Parent in Comet Nuclei. Jupiter-family comets are ephemeral small bodies injected into the inner solar system from the Kuiper Belt, doomed to either sublimate all their volatiles and become inert or violently shatter from the activity. We investigate two target candidates of the ESA Rosetta mission, comets 46P/Wirtanen and 67P/Churyumov-Gerasimenko, which had favorable apparitions for Earth-based observations in 2018-2019 and 2021, respectively. Using the Hubble Space Telescope STIS and COS instruments, we observed OH and CS emissions to characterize production rates of H2O and CS, established Af ρ values, and placed upper limits on the production rate of C2 and its parent. We find CS/H2O relative abundances that are significantly (5σ-7σ) larger than previous remote near-UV (NUV) measurements of 46P and 67P at similar heliocentric distances and CS/H2O values larger than those obtained via contemporaneous submillimeter observations for the same apparitions. We also find that for 67P the remote derivations of CS2/H2O ratios are substantially (~50×) higher than the values measured by the ROSINA mass spectrometer on board the Rosetta spacecraft for all NUV-derived CS2 production rates. The discrepancy points toward an unidentified CS parent or parents with contributing factors from uncertainties with the fluorescence efficiencies of the CS (0,0) band of the A 1Π-X 1Σ+ system around 2580 Å. Given the significance of understanding the chemistry and dissociation physics of sulfur-bearing molecules in comets for tracing planetesimal formation environments, as well as the limited studies in this area, we propose several hypotheses to explain this discrepancy and outline future studies to address these issues.

Keywords: Hubble Space Telescope, Ultraviolet observatories, Short period comets, Molecular spectroscopy, Atomic spectroscopy
Toward 3D Retrieval of Exoplanet Atmospheres: Assessing Thermochemical Equilibrium Estimation Methods. Characterizing exoplanetary atmospheres via Bayesian retrievals requires assuming some chemistry model, such as thermochemical equilibrium or parameterized abundances. The higher-resolution data offered by upcoming telescopes enable more complex chemistry models within retrieval frameworks. Yet many chemistry codes that model more complex processes like photochemistry and vertical transport are computationally expensive, and directly incorporating them into a 1D retrieval model can result in prohibitively long execution times. Additionally, phase-curve observations with upcoming telescopes motivate 2D and 3D retrieval models, further exacerbating the lengthy runtime for retrieval frameworks with complex chemistry models. Here we compare thermochemical equilibrium approximation methods based on their speed and accuracy with respect to a Gibbs energy-minimization code. We find that, while all methods offer orders-of-magnitude reductions in computational cost, neural network surrogate models perform more accurately than the other approaches considered, achieving a median absolute dex error of &lt;0.03 for the phase space considered. While our results are based on a 1D chemistry model, our study suggests that higher-dimensional chemistry models could be incorporated into retrieval models via this surrogate modeling approach.

Keywords: Exoplanet atmospheric composition , Regression, Neural networks, Chemical abundances, Exoplanet atmospheres
Phase Curves of Kuiper Belt Objects, Centaurs, and Jupiter-family Comets from the ATLAS Survey. The Kuiper Belt objects (KBOs), the Centaurs, and the Jupiter-family comets (JFCs) form an evolutionary continuum of small outer solar system objects, and their study allows us to gain insight into the history and evolution of the solar system. Broadband photometry can be used to measure their phase curves, allowing a first-order probe into the surface properties of these objects, though limited telescope time makes measuring accurate phase curves difficult. We make use of serendipitous broadband photometry from the long-baseline, high-cadence Asteroid Terrestrial-impact Last Alert System survey to measure the phase curves for a sample of 18 KBOs, Centaurs, and JFCs with unprecedentedly large data sets. We find phase curves with previously reported negative slopes become positive with increased data and are thus due to insufficient sampling of the phase-curve profile, and not a real physical effect. We search for correlations between phase-curve parameters, finding no strong correlations between any parameter pair, consistent with the findings of previous studies. We search for instances of cometary activity in our sample, finding a previously reported outburst by Echeclus and a new epoch of increased activity by Chiron. Applying the main belt asteroid HG 1 G 2 phase-curve model to three JFCs in our sample with large phase angle spans, we find their slope parameters imply surfaces more consistent with those of carbonaceous main belt asteroids than silicaceous ones.

Keywords: Phase angle, Kuiper belt, Centaur group, Wide-field telescopes, Short period comets, Solar system, Trans-Neptunian objects, Broad band photometry
A High Spatial and Spectral Resolution Study of Jupiter's Mid-infrared Auroral Emissions and Their Response to a Solar Wind Compression. We present mid-infrared spectroscopy of Jupiter's mid-to-high latitudes using the Gemini-North/Texas Echelon Cross Echelle Spectrograph on 2017 March 17-19. These observations capture Jupiter's hydrocarbon auroral emissions before, during, and after the arrival of a solar wind compression on March 18, which highlights the coupling between the polar stratosphere and external space environment. In comparing observations on March 17 and 19, we observe a brightening of the CH4, C2H2, and C2H4 emission in regions spatially coincident with the northern duskside main auroral emission (MAE). In inverting the spectra to derive atmospheric information, we determine that the duskside brightening results from upper stratospheric (p &lt; 0.1 mbar/z &gt; 200 km) heating (e.g., ∆T = 9.1 ± 2.1 K at 9 μbar at 67.°5N, 162.°5W) with negligible heating at deeper pressures. Our interpretation is that the arrival of the solar wind enhancement drove magnetospheric dynamics through compression and/or viscous interactions on the flank. These dynamics accelerated currents and/or generated higher Poynting fluxes, which ultimately warmed the atmosphere through Joule heating and ion-neutral collisions. Poleward of the southern MAE, temperature retrievals demonstrate that auroral-related heating penetrates as deep as the 10 mbar level, in contrast to poleward of the northern MAE, where heating is only observed as deep as ~3 mbar. We suggest that this results from the south having higher Pedersen conductivities and therefore stronger currents and acceleration of the neutrals, as well as the poleward heating overlapping with the apex of Jupiter's circulation, thereby inhibiting efficient horizontal mixing/advection.

Keywords: High resolution spectroscopy, Planetary polar regions, Aeronomy, Planetary atmospheres, Jupiter, Aurorae, Infrared astronomy, Planetary magnetospheres