The Planetary Science Journal最新文献

{"title":"Probing the Rock Mass Fraction and Transport Efficiency inside Uranus Using 40Ar Measurements","authors":"Francis Nimmo, Jonathan Lunine, Kevin Zahnle and Lars Stixrude","doi":"10.3847/psj/ad3b93","DOIUrl":"https://doi.org/10.3847/psj/ad3b93","url":null,"abstract":"The bulk of Uranus consists of a rock–ice core, but the relative proportions of rock and ice are unknown. Radioactive decay of potassium in the silicates produces 40Ar. If transport of argon from the core to the gaseous envelope is efficient, a measurement of 40Ar in the envelope will provide a direct constraint on the rock mass present (assuming a chondritic rock composition). The expected 40Ar concentrations in this case would be readily detectable by a mass spectrometer carried by a future atmospheric probe. For a given envelope concentration there is a trade-off between the rock mass present and the transport efficiency; this degeneracy could be overcome by making independent determinations of the rock mass (e.g., by gravity and seismology). Primordial 40Ar is a potential confounding factor, especially if Ar/H2 is significantly enhanced above solar or if degassing of radiogenic 40Ar were inefficient. Unfortunately, the primordial 40Ar/36Ar ratio is very uncertain; better constraints on this ratio through measurement or theory would be very helpful. Pollution of the envelope by silicates is another confounding factor but can be overcome by a measurement of the alkali metals in the envelope.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140886779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative Mid-infrared Spectroscopy of Dark, Primitive Asteroids: Does Shared Taxonomic Class Indicate Shared Silicate Composition?","authors":"Oriel A. Humes, Audrey C. Martin, Cristina A. Thomas and Joshua P. Emery","doi":"10.3847/psj/ad3a69","DOIUrl":"https://doi.org/10.3847/psj/ad3a69","url":null,"abstract":"Primitive asteroids with low albedos and red slopes in the visible and near-infrared (VNIR) are found in both the main belt and the Jupiter Trojan clouds. In order to determine whether the VNIR spectral similarities of primitive main-belt asteroids and Jupiter Trojans are reflective of a true compositional similarity, we compare the mid-infrared silicate emission features of main-belt and Jupiter Trojan asteroids. Using archival data from the Spitzer Space Telescope’s Infrared Spectrograph and observations from the Stratospheric Observatory for Infrared Astronomy’s FORCAST instrument, we analyze the 5–40 μm spectra of 13 primitive main-belt asteroids and compare them to those of Jupiter Trojans in the literature. We find that while many primitive asteroids in the main belt resemble their Trojan counterparts with strong spectral signatures of olivine-rich high-porosity silicate regoliths, we identify (368) Haidea as a spectrally distinctive asteroid that lacks strong evidence of olivine in its mid-IR spectrum. Differences in silicate compositions among D-type asteroids imply a diversity of origins for primitive asteroids.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"43 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140886867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pwyll and Manannán Craters as a Laboratory for Constraining Irradiation Timescales on Europa","authors":"M. Ryleigh Davis and Michael E. Brown","doi":"10.3847/psj/ad3944","DOIUrl":"https://doi.org/10.3847/psj/ad3944","url":null,"abstract":"We examine high-spatial-resolution Galileo/Near-Infrared Mapping Spectrometer observations of the young (∼1 My–∼20 My) impact features, Pwyll and Manannán craters, on Europa’s trailing hemisphere in an effort to constrain irradiation timescales. We characterize their composition using a linear spectral modeling analysis, and find that both craters and their ejecta are depleted in hydrated sulfuric acid relative to nearby older terrain. This suggests that the radiolytic sulfur cycle has not yet had enough time to build up an equilibrium concentration of H2SO4, and places a strong lower limit of the age of the craters on the equilibrium timescale of the radiolytic sulfur cycle on Europa's trailing hemisphere. Additionally, we find that the dark and red material seen in the craters and proximal ejecta of Pwyll and Manannán show the spectroscopic signature of hydrated, presumably endogenic salts. This suggests that the irradiation-induced darkening and reddening of endogenic salts thought to occur on Europa’s trailing hemisphere has already happened at Pwyll and Manannán, thereby placing an upper limit on the timescale by which salts are irradiation reddened.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"60 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140834223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Possible Anthropogenic Contributions to the LAMP-observed Surficial Icy Regolith within Lunar Polar Craters: A Comparison of Apollo and Starship Landings","authors":"William M. Farrell, P. Prem, D. M. Hurley, O. J. Tucker, R. M. Killen","doi":"10.3847/psj/ad37f5","DOIUrl":"https://doi.org/10.3847/psj/ad37f5","url":null,"abstract":"This work assesses the potential of midsized and large human landing systems to deliver water from their exhaust plumes to cold traps within lunar polar craters. It has been estimated that a total of between 2 and 60 T of surficial water was sensed by the Lunar Reconnaissance Orbiter Lyman Alpha Mapping Project on the floors of the larger permanently shadowed south polar craters. This intrinsic surficial water sensed in the far-ultraviolet is thought to be in the form of a 0.3%–2% icy regolith in the top few hundred nanometers of the surface. We find that the six past Apollo Lunar Module midlatitude landings could contribute no more than 0.36 T of water mass to this existing, intrinsic surficial water in permanently shadowed regions (PSRs). However, we find that the Starship landing plume has the potential, in some cases, to deliver over 10 T of water to the PSRs, which is a substantial fraction (possibly >20%) of the existing intrinsic surficial water mass. This anthropogenic contribution could possibly overlay and mix with the naturally occurring icy regolith at the uppermost surface. A possible consequence is that the origin of the intrinsic surficial icy regolith, which is still undetermined, could be lost as it mixes with the extrinsic anthropogenic contribution. We suggest that existing and future orbital and landed assets be used to examine the effect of polar landers on the cold traps within PSRs.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140834423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The History of Eruptions at Acala Fluctus, Io: Source of Multiple Outbursts","authors":"Julie A. Rathbun, Madeline Pettine, Moses Milazzo and Christian Tate","doi":"10.3847/psj/ad38be","DOIUrl":"https://doi.org/10.3847/psj/ad38be","url":null,"abstract":"Recent ground-based Infrared Telescope Facility observations showed that a hot spot observed at the location of the surface feature Acala Fluctus was volcanically active for ∼18 months in 2019–2020 and exhibited two outbursts with a temperature of ∼1200 K. A high-temperature hot spot at Acala was also observed by Galileo SSI in the late 1990s over multiple flybys. Low-temperature hot spots in this area were detected in 2000 by the Galileo Photopolarimeter Radiometer and in 1979 by Voyager IRIS. However, neither the Galileo NIMS instrument nor any instrument on the New Horizons spacecraft, which flew by Io in 2007, saw any evidence of an Acala hot spot. It is also possible that earlier ground-based disk-integrated observations of hot spots are due to Acala, even though they were originally attributed to other volcanoes, such as Loki. These include outbursts in 1978 and 1990 and a persistent low-temperature source in the 1980 and 1990s. From these observations, we propose that Acala consists of highly variable high-temperature fire fountains and a large area of low-temperature, older flows. Due to these recent outbursts, we expect that any images of Acala obtained by JunoCam will show surface changes from Galileo images.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"54 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140834222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stellar Occultations in the Era of Data Mining and Modern Regression Models: Using Gaussian Processes to Analyze Light Curves and Improve Predictions","authors":"Bastian Knieling, Karsten Schindler, Amanda A. Sickafoose, Michael J. Person, Stephen E. Levine and Alfred Krabbe","doi":"10.3847/psj/ad3819","DOIUrl":"https://doi.org/10.3847/psj/ad3819","url":null,"abstract":"Gaussian process (GP) regression is a nonparametric Bayesian approach that has been used successfully in various astronomical domains, especially in time-domain astronomy. The most common applications are the smoothing of data for interpolation and the detection of periodicities. The ability to create unbiased data-driven models without a predefined physical model can be a major advantage over conventional regression methods. Prior knowledge can be included by setting boundary conditions or constraining hyperparameter values, while unknown hyperparameters are optimized during the conditioning of the model. We have adapted and transformed previous approaches of GP regression and introduce three new applications for this regression method, especially in the context of stellar occultations: the modeling of occultation light curves, the correction of public JPL ephemerides of minor planets based on publicly available image data of the Zwicky Transient Facility, and the detection of natural satellites. We used data from observations of stellar occultations to validate the models and achieved promising results in all cases, and thus we confirmed the flexibility of GP regression models. Considering various existing use cases in addition to our novel applications, GP regression can be used to model diverse data sets addressing a wide range of problems. The accuracy of the model depends on the input data and on the set boundary conditions. Generally, high-quality data allow the usage of loose boundary conditions, while low-quality data require more restrictive boundary conditions to avoid overfitting.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140800747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat-flux-limited Cloud Activity and Vertical Mixing in Giant Planet Atmospheres with an Application to Uranus and Neptune","authors":"Huazhi Ge, 华志 葛, Cheng Li, Xi Zhang and Chris Moeckel","doi":"10.3847/psj/ad0ed3","DOIUrl":"https://doi.org/10.3847/psj/ad0ed3","url":null,"abstract":"Storms operated by moist convection and the condensation of CH4 or H2S have been observed on Uranus and Neptune. However, the mechanism of cloud formation, thermal structure, and mixing efficiency of ice giant weather layers remains unclear. In this paper, we show that moist convection is limited by heat transport on giant planets, especially on ice giants where planetary heat flux is weak. Latent heat associated with condensation and evaporation can efficiently bring heat across the weather layer through precipitations. This effect was usually neglected in previous studies without a complete hydrological cycle. We first derive analytical theories and show that the upper limit of cloud density is determined by the planetary heat flux and microphysics of clouds but is independent of the atmospheric composition. The eddy diffusivity of moisture depends on the planetary heat fluxes, atmospheric composition, and surface gravity but is not directly related to cloud microphysics. We then conduct convection- and cloud-resolving simulations with SNAP to validate our analytical theory. The simulated cloud density and eddy diffusivity are smaller than the results acquired from the equilibrium cloud condensation model and mixing length theory by several orders of magnitude but consistent with our analytical solutions. Meanwhile, the mass-loading effect of CH4 and H2S leads to superadiabatic and stable weather layers. Our simulations produced three cloud layers that are qualitatively similar to recent observations. This study has important implications for cloud formation and eddy mixing in giant planet atmospheres in general and observations for future space missions and ground-based telescopes.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140800668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-dimensional Atmospheric Dynamics of Jupiter from Ground-based Doppler Imaging Spectroscopy in the Visible","authors":"Francois-Xavier Schmider, Patrick Gaulme, Raúl Morales-Juberías, Jason Jackiewicz, Ivan Gonçalves, Tristan Guillot, Amy A. Simon, Michael H. Wong, Thomas Underwood, David Voelz, Cristo Sanchez, Riley DeColibus, Sarah A. Kovac, Sean Sellers, Doug Gilliam, Patrick Boumier, Thierry Appourchaux, Julien Dejonghe, Jean Pierre Rivet, Steve Markham, Saburo Howard, Lyu Abe, Djamel Mekarnia, Masahiro Ikoma, Hidekazu Hanayama, Bun’ei Sato, Masanobu Kunitomo, Hideyuki Izumiura","doi":"10.3847/psj/ad3066","DOIUrl":"https://doi.org/10.3847/psj/ad3066","url":null,"abstract":"We present three-dimensional (3D) maps of Jupiter’s atmospheric circulation at cloud-top level from Doppler-imaging data obtained in the visible domain with JIVE, the second node of the JOVIAL network, which is mounted on the Dunn Solar Telescope at Sunspot, New Mexico. We report on 12 nights of observations between 2018 May 4 and May 30, representing a total of about 80 hr. First, the average zonal wind profile derived from our data is compatible with that derived from cloud-tracking measurements performed on Hubble Space Telescope images obtained in 2018 April from the Outer Planet Atmospheres Legacy program. Second, we present the first ever 2D maps of Jupiter’s atmospheric circulation from Doppler measurements. The zonal velocity map highlights well-known atmospheric features, such as the equatorial hot spots and the Great Red Spot (GRS). In addition to zonal winds, we derive meridional and vertical velocity fields from the Doppler data. The motions attributed to vertical flows are mainly located at the boundary between the equatorial belts and tropical zones, which could indicate active motion in theses regions. Qualitatively, these results compare well to recent Juno data that have unveiled the 3D structure of Jupiter’s wind field. To the contrary, the motions attributed to meridional circulation are very different from what is obtained by cloud tracking, except at the GRS. Because of limitations with data resolution and processing techniques, we acknowledge that our measurements of the vertical or meridional flows of Jupiter are still to be confirmed.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"126 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140610029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"History of Ceres’s Cold Traps Based on Refined Shape Models","authors":"Norbert Schorghofer, Robert Gaskell, Erwan Mazarico, John Weirich","doi":"10.3847/psj/ad3639","DOIUrl":"https://doi.org/10.3847/psj/ad3639","url":null,"abstract":"Permanently shadowed regions (PSRs) in the north polar region of Ceres have been previously mapped by the Dawn spacecraft. Putative ice deposits are found in some of these PSRs, whereas most PSRs host no bright deposits, which is thought to be due to oscillations of the axis tilt with a ∼25 ka period. We use stereophotoclinometry to construct refined topographic models of PSR-hosting craters. Ray-tracing calculations reveal that no PSRs remain at the maximum axis tilt, which implies that the ice deposits are remarkably young. The bright ice deposits do not extend beyond PSRs at an axis tilt of 10°, which last occurred about 6 ka ago. This suggests that water is delivered to the polar regions or exposed within the craters by frequent and short-lived events. Surface temperatures are calculated with a terrain irradiance model to delineate cold traps. Based on maximum equilibrium temperatures, Cerean PSRs are too warm to trap supervolatiles.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140610089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurements of Titan’s Stratospheric Winds during the 2009 Equinox with the eSMA","authors":"Siobhan Light, Mark Gurwell, Alexander Thelen, Nicholas A Lombardo, Conor Nixon","doi":"10.3847/psj/ad3355","DOIUrl":"https://doi.org/10.3847/psj/ad3355","url":null,"abstract":"Saturn’s moon Titan possesses stratospheric zonal winds that places it among a sparse class of planetary bodies known to have superrotation in their atmospheres. Few measurements have been made of these speeds in the upper stratosphere, leaving their seasonal variations still not well understood. We examined observations made with the extended Submillimeter Array in 2009 March (<italic toggle=\"yes\">L</italic>\u0000_{\u0000<italic toggle=\"yes\">s</italic>\u0000} = 355°) and 2010 February (<italic toggle=\"yes\">L</italic>\u0000_{\u0000<italic toggle=\"yes\">s</italic>\u0000} = 5°), shortly before and after Titan's northern spring equinox. Cassini observations and atmospheric models find equinoctial periods to be especially dynamic. Zonal wind calculations, derived from the Doppler frequency shift of CH₃CN near 349.4 GHz, yielded speeds of 128 ± 27 m s⁻¹ in 2009 and 209 ± 48 m s⁻¹ in 2010. We estimated the measured emission to originate from vertical altitudes of <inline-formula>\u0000<tex-math>\u0000<?CDATA ${336}_{-88}^{+112}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mrow><mml:mn>336</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>88</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>112</mml:mn></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"psjad3355ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> km, equivalent to pressures of <inline-formula>\u0000<tex-math>\u0000<?CDATA ${3.8}_{-3.4}^{+19.2}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mrow><mml:mn>3.8</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>3.4</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>19.2</mml:mn></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"psjad3355ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> Pa, commensurate with Titan’s upper stratosphere/lower mesosphere. This suggests a possible increase in zonal speeds during this period. The results are then compared to those from previous Cassini-inferred and direct-interferometric observations of winds, as well as general circulation model simulations, to form a more complete picture of the seasonal cycle of stratospheric zonal winds.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"888 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140610608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}