Journal of Geophysical Research: Planets最新文献

{"title":"Martian Atmospheric Disturbances From Orbital Images and Surface Pressure at Jezero Crater, Mars, During Martian Year 36","authors":"A. Sánchez-Lavega,&nbsp;E. Larsen,&nbsp;T. del Rio-Gaztelurrrutia,&nbsp;J. Hernández-Bernal,&nbsp;I. Ordóñez-Etxebarría,&nbsp;R. Hueso,&nbsp;B. Tanguy,&nbsp;M. Lemmon,&nbsp;M. de la Torre Juarez,&nbsp;G. M. Martínez,&nbsp;A. Munguira,&nbsp;J. A. Rodríguez-Manfredi,&nbsp;A.-M. Harri,&nbsp;J. Pla-García,&nbsp;D. Toledo,&nbsp;C. Newman","doi":"10.1029/2024JE008565","DOIUrl":"https://doi.org/10.1029/2024JE008565","url":null,"abstract":"<p>We present a study of atmospheric disturbances at Jezero Crater, Mars, using ground-based measurements of surface pressure by the Perseverance rover in combination with orbital images from the Mars Express and Mars Reconnaissance Orbiter missions. The study starts at L_s ∼ 13.3° in MY36 (6 March 2021) and extends up to L_s ∼ 30.3° in MY37 (28 February 2023). We focus on the characterization of the major atmospheric phenomena at synoptic and planetary-scales. These are the thermal tides (measured up to the sixth component), long-period pressure oscillations (periods &gt;1 sol), the Aphelion Cloud Belt, and the occasional development of regional dust storms over Jezero. We present the seasonal evolution of the amplitudes and phases of the thermal tides and their relation with the atmospheric dust content (optical depth). Three regional dust storms and one polar storm extending over Jezero produced an increase in the diurnal and semidiurnal amplitudes but resulted in inverse responses in their phases. We show that the primary regular wave activity is due to baroclinic disturbances with periods of 2–4 sols and amplitudes ∼ 1–15 Pa increasing with dust content, in good agreement with theoretical predictions by model calculations. The spacecraft images show a number of arc-shaped, spiral and irregular cyclonic vortices, traced by dust and clouds at the edge of the North Polar Cap, that could be behind some of the pressure oscillations measured at Jezero.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008565","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simple-To-Complex Crater Transition for the Uranian Satellites Ariel and Miranda","authors":"M. E. Borrelli,&nbsp;C. J. Bierson,&nbsp;J. G. O’Rourke","doi":"10.1029/2024JE008507","DOIUrl":"https://doi.org/10.1029/2024JE008507","url":null,"abstract":"<p>The latest decadal survey identified the Uranus system as the highest-priority new target for a NASA Flagship mission. Ariel and Miranda are potential ocean worlds with evidence of resurfacing potentially due to past elevated heat flow. Learning about the geologic histories of these icy moons is important for understanding the potential for life in the outer solar system. Using limited data acquired by the Voyager 2 spacecraft, we explore open questions about the surfaces of Uranian satellites to gain a better understanding of their evolutionary histories. In this work, we update the estimates of Ariel and Miranda's simple-to-complex transition diameters, which have not yet been measured using modern GIS techniques and reprocessed data. The simple-to-complex transition diameter is a value used on many worlds to infer the composition of the surface. For the Uranian satellites, this value was last estimated shortly after the Voyager 2 flyby with a data set of 18 craters. We use reprocessed topography from more than 100 craters to estimate a simple-to-complex transition diameter on Ariel of ∼26 km, consistent with an icy surface composition. We place a lower limit of ∼49 km on the transition diameter for Miranda, where we cannot identify any complex craters. We also estimate the relative and absolute ages of terrains on Ariel and Miranda. Our results agree with recent studies showing that they likely experienced relatively recent (≤1 Gya) resurfacing. Finally, we suggest imaging requirements for the future missions to Uranus to answer outstanding questions about Ariel and Miranda.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008507","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Clouds and Ammonia in the Atmospheres of Jupiter and Saturn Determined From a Band-Depth Analysis of VLT/MUSE Observations","authors":"Patrick G. J. Irwin,&nbsp;Steven M. Hill,&nbsp;Leigh N. Fletcher,&nbsp;Charlotte Alexander,&nbsp;John H. Rogers","doi":"10.1029/2024JE008622","DOIUrl":"https://doi.org/10.1029/2024JE008622","url":null,"abstract":"<p>The visible spectrum of Jupiter contains absorption bands of methane (619 nm) and ammonia (647 nm) that can be used to probe the cloud-top pressures and ammonia abundance in Jupiter's atmosphere. Recently, it has been shown that filter-averaged observations of Jupiter made with telescopes and filters accessible to backyard astronomers can be reduced to yield ammonia maps that bear a remarkable similarity with distributions derived using more complex radiative transfer methods. Here, we determine the reliability of this method by applying it to observations made with the MUSE instrument at ESO's Very Large Telescope, and find excellent correspondence with the retrieved products from multiple-scattering retrieval model analyses. We find that the main level of reflection in Jupiter's atmosphere is at 2–3 bar, which is far beneath the anticipated ammonia ice condensation level at <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math> 0.7 bar, and conclude that pure ammonia ice cannot be the main cloud constituent. We show that the spatial variations of ammonia determined at 2–3 bar are strongly correlated with those determined from thermal-infrared observations, and microwave observations by the Very Large Array and the Juno spacecraft. Finally, we show that the same technique can be applied to observations of Saturn, again yielding maps of ammonia abundance at 2–3 bar that are well-correlated with thermal-IR observations made near 5 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>μ</mi>\u0000 </mrow>\u0000 <annotation> $mu $</annotation>\u0000 </semantics></math>m by Cassini/VIMS and JWST/MIRI. Similarly, the main level of reflectivity is found to be lie far beneath the expected condensation level of ammonia in Saturn's atmosphere at <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math> 1.8 bar.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008622","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effect of Ground Ice Redistribution on the Martian Paleo-\u0000 \u0000 \u0000 \u0000 CO\u0000 2\u0000 \u0000 \u0000 ${text{CO}}_{2}$\u0000 Cycle","authors":"E. David,&nbsp;O. Aharonson,&nbsp;E. Vos,&nbsp;N. Schörghofer","doi":"10.1029/2024JE008398","DOIUrl":"https://doi.org/10.1029/2024JE008398","url":null,"abstract":"&lt;p&gt;&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;mi&gt;O&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{C}mathrm{O}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; is the primary component of the martian atmosphere and its seasonal surface-atmosphere exchange is responsible for many of the climate phenomena on the planet. Near-surface ground water ice (’GI’) has been found to inhibit seasonal &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;CO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{CO}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; ice accumulations. Previous studies concerning the response of the &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;CO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{CO}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; cycle to orbital variations did not take into account the redistribution of GI arising from the same orbital variations. This work aims to analyze the effect of GI redistribution on the &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;CO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{CO}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; cycle in past climates. We use the LMD Planetary Climate Model to simulate the full &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;CO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{CO}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; cycle at different orbital configurations and compare simulations with reference modern GI as observed by the Mars Odyssey Neutron Spectrometer (“MONS GI” scenario) to simulations with equilibrium GI produced by the Mars Subsurface Ice Model (“Eq. GI” scenario). In the Eq. GI scenario, equilibrium GI underlies 0.8–0.9 of the seasonal caps area at high obliquity periods, whereas in the reference MONS GI scenario, the overlap between GI and the seasonal cap is reduced, reaching less than 0.3 by obliquity &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;45&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $45{}^{circ}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. The mass and duration of seasonal &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 ","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143121181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved Models of Ganymede's Permanent and Induced Magnetic Fields Based on Galileo and Juno Data","authors":"Xianzhe Jia,&nbsp;Margaret G. Kivelson,&nbsp;Krishan K. Khurana,&nbsp;Raymond J. Walker","doi":"10.1029/2024JE008309","DOIUrl":"https://doi.org/10.1029/2024JE008309","url":null,"abstract":"<p>Near Ganymede, the magnetic field is a superposition of Jupiter's magnetospheric magnetic field, the field arising from sources within the moon, the field generated by plasma currents driven by the interaction of flowing magnetospheric plasma with the conducting moon, and the field arising from ionospheric currents. Previous fits to Ganymede's internal field have not identified the contributions of plasma and ionospheric currents, although their contributions can obscure the signature of sources internal to the moon. Fortunately, using magnetohydrodynamic simulations whose output agrees well with the measurements acquired on close passes by Galileo and Juno, we can estimate the moon-scale contributions of plasma sources. By subtracting the magnetic signatures of plasma and ionospheric currents from the measured field, we approximate measurements made in a current-free region. We fit the corrected data from different sets of flybys either as a sum of low order spherical harmonics or as a permanent dipole moment plus an induced dipole with approximately the same root-mean-square errors. For the induced dipole model, data from multiple flybys occurring at different phases of Jupiter's rotation are used to represent the time-variation of the external field at Ganymede. Compared with earlier estimates, the magnitude of the permanent dipole moment did not significantly change in either analysis. However, for the permanent plus induced dipole model, the induction efficiency decreases from 0.84 to ∼0.72. The reduced efficiency places new constraints on the thickness of the ice shell above the ocean and the ocean's depth and conductivity.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008309","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143121510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Liquid Structure of Iron and Iron–Nitrogen–Carbon Alloys Within the Cores of Small Terrestrial Bodies","authors":"Allison Pease,&nbsp;Jiachao Liu,&nbsp;Mingda Lv,&nbsp;Jack Piper,&nbsp;Yoshio Kono,&nbsp;Susannah M. Dorfman","doi":"10.1029/2024JE008599","DOIUrl":"https://doi.org/10.1029/2024JE008599","url":null,"abstract":"<p>Nitrogen has been proposed to be stored within planetary cores, but its effects on the structure and density of molten Fe–alloys have not been explored experimentally. Using energy-dispersive X-ray diffraction, we determined the structure of Fe–N(–C) liquids at core conditions (1–7 GPa and 1700–1900°C) within a Paris-Edinburgh press. Variation of N up to 7 wt.% and C up to 1.5 wt.% results in near-linear changes in Fe–Fe atom distances and structure factor with increasing light element content. We did not observe a significant pressure-driven structural transition in Fe–N(–C) liquids. We model the expansion of the Fe–Fe bonds using a modified Birch-Murnaghan equation of state. With this model, we demonstrate that N or C contamination could lead to an overestimation of the Fe–Fe distances of pure Fe. We observe that the incorporation of 1 wt.% N or C into Fe results in a change in Fe–Fe distances that is twice as significant as the effect of 1 GPa. By approximating the change in volume, we infer that N and C incorporated in liquid iron could contribute to the density deficit observed in the cores of terrestrial bodies.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008599","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143121509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Major and Trace Element Variations and Lithologic Component Analysis in Apollo 17 Drive Tube 73001/2","authors":"Mason Neuman,&nbsp;Piers Koefoed,&nbsp;Kun Wang,&nbsp;Bradley L. Jolliff,&nbsp;Randy L. Korotev,&nbsp;Richard V. Morris","doi":"10.1029/2024JE008373","DOIUrl":"https://doi.org/10.1029/2024JE008373","url":null,"abstract":"<p>Samples 73001 and 73002, which make up the lower and upper portions, respectively, of the double drive tube containing regolith (“soil”) collected on the “light mantle” at Station 3 during Apollo 17. Using a quadrupole inductively coupled plasma-mass spectrometer (ICP-MS) and fused-bead electron-probe microanalysis (FB-EPMA), we determined the chemical composition of every 0.5 cm dissection interval of the entire 56.9 cm length of the double drive tube, which penetrated to a depth of 70.6 cm below the regolith surface. We used the chemical compositions to model the proportions of different lithologic components found at the Apollo 17 site. Elemental variations with depth were linked to different proportions of these components. Higher amounts of high-Ti mare basalt near the 73002 surface (uniformly dark-toned regolith from 0 to 1.5 cm) indicate mixing of local mare materials by small impact cratering. Decreasing proportions of high-Ti mare basalt below 1.5 cm result from the mixing of dark and light regolith components during the dissection process on Earth. Below about 7.5 cm, compositions indicate consistent amounts of primarily highlands material (&lt;5% high-Ti mare basalt), which can be described as a mixture of noritic impact-melt and anorthositic-norite components. In detail, the modeled anorthositic-norite component, which may represent the pre-basin upper crust in this part of the Moon, ranges from 50 to 60 wt.%. The modeled noritic impact-melt breccia component remains relatively uniform at 35–40 wt.% throughout the length of 73002 and increases to 45 wt.% at the bottom of 73001.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008373","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143120964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Periglacial Landforms and Estimated Subsurface Ice Distribution in the Northern Mid-Latitude of Mars","authors":"Takaki Sako,&nbsp;Hitoshi Hasegawa,&nbsp;Trishit Ruj,&nbsp;Goro Komatsu,&nbsp;Yasuhito Sekine","doi":"10.1029/2023JE008232","DOIUrl":"https://doi.org/10.1029/2023JE008232","url":null,"abstract":"<p>Subsurface ice in the mid-latitude regions is a significant water inventory on present-day Mars, and their volume and distribution are thought to have varied due to the orbitally induced paleoclimatic changes. Using high-resolution satellite images, the present study explores the distributions of three presumed periglacial landforms (thermal contraction polygons, fractured mounds, and brain terrains) that could provide evidence for the present-day subsurface ice distribution in the northern mid-latitude (30°–42°N). We identified the three periglacial landforms concentrated within the regions of 0°–40°E, 60°–100°E, and 160°–210°E in the latitude of &gt;33°N. Their distributions are in agreement with the occurrence of fresh ice-exposing craters and the estimated area of high annual water ice budget obtained by the general circulation model, reflecting the present-day subsurface ice distribution. We further classified the thermal contraction polygons into five types based on their morphology, and investigated various distribution patterns for each type. Among them, high-centered polygons are the most abundant type in the survey area, whereas low-centered polygons are less prominent and observed only at &gt;38°N. The large-sized mixture polygons, which were only found in certain areas of 57°–92°E, are distributed in areas where the atmospheric model indicates that the highest annual water ice budget occurred during the past high-obliquity period, but that the water ice budget has decreased during the present-day low-obliquity condition. These findings, along with insights from possible terrestrial analogs in the Arctic Archipelago and northern Canada, suggest that regions where large-sized mixture polygons formed contained significant amounts of water ice in the past, but have undergone intense degradation over time.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JE008232","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143121046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geological Background of the Chang'e 6 Landing Site and the Provenance of Returned Samples","authors":"Antong Gao,&nbsp;Long Xiao,&nbsp;Lukas Wueller,&nbsp;Wajiha Iqbal,&nbsp;Siyuan Zhao,&nbsp;Jiang Wang,&nbsp;Carolyn H. van der Bogert,&nbsp;Yuqi Qian,&nbsp;Yong Pang,&nbsp;Harald Hiesinger","doi":"10.1029/2024JE008658","DOIUrl":"https://doi.org/10.1029/2024JE008658","url":null,"abstract":"<p>China's Chang'e-6 (CE-6) is the first mission in human history to return samples from the far side of the Moon. CE-6 landed in the mare plains of the southern Apollo basin (153.98°W, 41.63°S) within the South Pole-Aitken (SPA) basin on 2 June 2024 and returned 1,935.3 g of samples on 25 June 2024. The unique geological history of the Apollo basin offers an opportunity to address several important scientific questions in lunar science. To provide geological context for the analysis of the returned samples, we described the geology of the area surrounding the CE-6 landing site in detail. We interpreted that the region exhibits three periods of mare basaltic volcanism (<i>EmSAp1</i>, <i>EmSAp2 and EmSAp3</i>) separated by one billion years. CE-6 landed on the <i>EmSAp2</i> unit, with a model age of ∼2.8 Ga. Several post-mare impacts occurring outside this region also contributed foreign materials to CE-6 landing site. We anticipate that the returned samples are dominated by local <i>EmSAp</i>2 materials, and may also include younger high-Ti basalt from the <i>EmSAp3</i> unit, older low-Ti basalt from the <i>EmSAp1</i> unit, ejecta from younger craters such as Chaffee S and O’Day, and ejecta from craters outside the SPA basin such as Vavilov, Crookes, and Das. The estimated total feldspathic exotic ejecta in the regolith of CE-6 sample zone is 30%. Our study indicates that the regolith in the CE-6 sampling area is rich in scientific value for understanding lunar volcanism and impact history and offers the possibility of further calibrating the lunar cratering chronology.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143120735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oblique Impact Adjacent to Chang'E−5 Sampling Site: Fine-Scale Analysis and Implication on the Provenance of Returned Samples","authors":"Wenhui Wu,&nbsp;Xin Ren,&nbsp;Zhaopeng Chen,&nbsp;Peng Zhang,&nbsp;Dawei Liu,&nbsp;Xingguo Zeng,&nbsp;Yuan Chen,&nbsp;Wangli Chen,&nbsp;Wei Yan,&nbsp;Bin Liu,&nbsp;Xiaoxia Zhang,&nbsp;Jianjun Liu","doi":"10.1029/2024JE008474","DOIUrl":"https://doi.org/10.1029/2024JE008474","url":null,"abstract":"<p>Impact ejecta is a major source of lunar regolith. Symmetric ejecta thickness models are widely used to estimate ejecta distribution. However, they cannot accurately describe the asymmetric distributions from oblique impacts. Here, the Xu Guangqi crater provides an example for the study of oblique impacts. High-resolution data from this crater, acquired during the Chang'E−5 mission, has facilitated studies of a potential oblique impact, the development of a correction model for asymmetric ejecta distribution, and a detailed analysis of regolith provenance at the sampling site. The results show that the Chang'E−5 returned samples mainly originate from the Xu Guangqi crater formed by an oblique impact at 25°–45°, and its corrected ejecta thickness at the sampling site is about 80 cm, an increase of about 30% over the estimate from the original symmetric ejecta thickness model. Within the uppermost 5 cm, the Chang'E−5 returned regolith is modeled to consist mainly of Xu Guangqi ejecta (∼99%) and a small number of local materials (∼1%), but both are similar in composition composed of local mare basalts. Although small quantities (∼0.7%) of nonlocal mare components from Sharp B, Copernicus, Harpalus, and Aristarchus occur at the bottom of the drilled samples (80–90 cm), the samples are still dominated by Xu Guangqi ejecta (∼88%) and local materials (∼11%). Our study demonstrates the possible effect of an oblique impact to be considered when discussing the sample provenance for a lunar sample returning mission.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143119927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}