Pub Date : 2025-01-06DOI: 10.1016/j.icarus.2025.116454
Linxi Li , Hejiu Hui , Sen Hu , Qiuli Li , Yi Chen , Wei Yang , Guoqiang Tang , Lihui Jia , Xiaoguang Li , Lixin Gu , Fuyuan Wu
Lunar regolith samples contain fragments of endogenic rocks and exogenous meteorites. We report the first discovery of a chondrule fragment preserved in Chang'e-5 (CE-5) regolith samples. Forsterite and enstatite phenocrysts have extremely high Mg# (> 99) and high Mn/Fe ratios in this chondrule fragment. Its glass mesostasis is heterogeneous and contains hydrogen and carbon, as indicated by Raman peaks. The mineral assemblage, chemical composition, and oxygen isotope anomaly of this fragment are similar to those of type-I chondrules from carbonaceous chondrites. This fragment and other chondritic relics with < 3.0 Ga impact ages exhibit compositional similarities to micrometeorites on Earth, but are different from ultramagnesian mafic fragments (UMMFs) discovered on the Moon with impact ages > 3.4 Ga. This contrast suggests that there may have been a change of impactors to the Earth–Moon system during the Imbrian period. Furthermore, this CE-5 chondrule fragment is a direct record of volatile addition to the Moon's surface from meteorites during the Eratosthenian period.
{"title":"Discovery of carbonaceous chondritic fragment in Chang'e-5 regolith samples","authors":"Linxi Li , Hejiu Hui , Sen Hu , Qiuli Li , Yi Chen , Wei Yang , Guoqiang Tang , Lihui Jia , Xiaoguang Li , Lixin Gu , Fuyuan Wu","doi":"10.1016/j.icarus.2025.116454","DOIUrl":"10.1016/j.icarus.2025.116454","url":null,"abstract":"<div><div>Lunar regolith samples contain fragments of endogenic rocks and exogenous meteorites. We report the first discovery of a chondrule fragment preserved in Chang'e-5 (CE-5) regolith samples. Forsterite and enstatite phenocrysts have extremely high Mg# (> 99) and high Mn/Fe ratios in this chondrule fragment. Its glass mesostasis is heterogeneous and contains hydrogen and carbon, as indicated by Raman peaks. The mineral assemblage, chemical composition, and oxygen isotope anomaly of this fragment are similar to those of type-I chondrules from carbonaceous chondrites. This fragment and other chondritic relics with < 3.0 Ga impact ages exhibit compositional similarities to micrometeorites on Earth, but are different from ultramagnesian mafic fragments (UMMFs) discovered on the Moon with impact ages > 3.4 Ga. This contrast suggests that there may have been a change of impactors to the Earth–Moon system during the Imbrian period. Furthermore, this CE-5 chondrule fragment is a direct record of volatile addition to the Moon's surface from meteorites during the Eratosthenian period.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"429 ","pages":"Article 116454"},"PeriodicalIF":2.5,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-03DOI: 10.1016/j.icarus.2024.116450
Caroline Brachmann , Lena Noack , Philipp Alexander Baumeister , Frank Sohl
After the magma ocean state, secondary atmospheres build up via early volcanic degassing of planetary interiors. The terrestrial planets Venus, Earth, and Mars are believed to have originated from similar source material but reveal distinct present-day atmospheric compositions, pressures, and temperatures. To investigate how such diverse atmospheres emerge, we have built a three-step model coupling mantle and atmospheric composition. The model incorporates mantle melting, melt ascent, and volcanic degassing. Additionally, it includes atmospheric equilibrium chemistry, taking into account processes such as water condensation and hydrogen escape. Key parameters such as mantle oxygen fugacity, melt production rates, surface temperature, and volatile abundance in the mantle, were varied to understand their impact on atmospheric composition and pressure. For reduced mantles with redox states below IW +1, atmospheric pressures remain strongly limited to a maximum of 2 bar due to the outgassing of predominantly light species that are prone to atmospheric escape or condensation. Above IW +1, atmospheric pressure can reach several tens of bars depending on the outgassing efficiency. For high-pressure atmospheres, CO2 is the main atmospheric species observed in our models. For oxidized low-pressure atmospheres, depending on temperature, atmospheres can be either water-rich or also CO2-dominated. For reducing atmospheres, nitrogen species tend to dominate the atmospheres, with NH3 for colder atmospheres and N2 for warmer atmospheres. CH4 becomes dominant only in a narrow parameter space at redox states around IW +0.5 to IW +2 and is favored by lower atmospheric temperatures.
{"title":"Distinct types of C-H-O-N atmospheres and surface pressures depending on melt redox state and outgassing efficiency","authors":"Caroline Brachmann , Lena Noack , Philipp Alexander Baumeister , Frank Sohl","doi":"10.1016/j.icarus.2024.116450","DOIUrl":"10.1016/j.icarus.2024.116450","url":null,"abstract":"<div><div>After the magma ocean state, secondary atmospheres build up via early volcanic degassing of planetary interiors. The terrestrial planets Venus, Earth, and Mars are believed to have originated from similar source material but reveal distinct present-day atmospheric compositions, pressures, and temperatures. To investigate how such diverse atmospheres emerge, we have built a three-step model coupling mantle and atmospheric composition. The model incorporates mantle melting, melt ascent, and volcanic degassing. Additionally, it includes atmospheric equilibrium chemistry, taking into account processes such as water condensation and hydrogen escape. Key parameters such as mantle oxygen fugacity, melt production rates, surface temperature, and volatile abundance in the mantle, were varied to understand their impact on atmospheric composition and pressure. For reduced mantles with redox states below IW +1, atmospheric pressures remain strongly limited to a maximum of 2 bar due to the outgassing of predominantly light species that are prone to atmospheric escape or condensation. Above IW +1, atmospheric pressure can reach several tens of bars depending on the outgassing efficiency. For high-pressure atmospheres, CO<sub>2</sub> is the main atmospheric species observed in our models. For oxidized low-pressure atmospheres, depending on temperature, atmospheres can be either water-rich or also CO<sub>2</sub>-dominated. For reducing atmospheres, nitrogen species tend to dominate the atmospheres, with NH<sub>3</sub> for colder atmospheres and N<sub>2</sub> for warmer atmospheres. CH<sub>4</sub> becomes dominant only in a narrow parameter space at redox states around IW +0.5 to IW +2 and is favored by lower atmospheric temperatures.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"429 ","pages":"Article 116450"},"PeriodicalIF":2.5,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143135203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-03DOI: 10.1016/j.icarus.2024.116452
Robert M. Haberle , Melinda A. Kahre , Tanguy Bertrand , Michael J. Wolff
We discuss and implement the physics of dust-gas non-equilibrium processes into 1-D radiative-convective and 3-D climate models to assess at what altitude dust and gas temperatures in the Martian atmosphere diverge and to what extent it affects the thermal structure, dynamics, and transport capabilities of the upper atmosphere. As found in an earlier paper by Goldenson et al. (2008), we find (using a different approach) that dust and gas temperatures diverge above 40 km as collisions between dust particles and gas molecules are too infrequent to equilibrate these two components. With our 1-D model we show that when dust-gas non-equilibrium physics is included, gas temperatures above 40 km cool and heating rates are reduced. The magnitude of the effect depends mostly on the size and abundance of the dust particles and is proportional to each. With our 3-D model we show that this physics is important mainly during times of intense dust lifting events such as local rocket storms, or regional or global storms when dust quickly penetrates to high altitudes and particle sizes can be somewhat larger at least initially. During such times upper atmosphere temperatures cool, wind systems are weakened, and vertical and meridional transport is diminished when compared to simulation assuming thermal equilibrium.
{"title":"Modeling studies of dust/gas non-thermal equilibrium in the Martian atmosphere","authors":"Robert M. Haberle , Melinda A. Kahre , Tanguy Bertrand , Michael J. Wolff","doi":"10.1016/j.icarus.2024.116452","DOIUrl":"10.1016/j.icarus.2024.116452","url":null,"abstract":"<div><div>We discuss and implement the physics of dust-gas non-equilibrium processes into 1-D radiative-convective and 3-D climate models to assess at what altitude dust and gas temperatures in the Martian atmosphere diverge and to what extent it affects the thermal structure, dynamics, and transport capabilities of the upper atmosphere. As found in an earlier paper by <span><span>Goldenson et al. (2008)</span></span>, we find (using a different approach) that dust and gas temperatures diverge above 40 km as collisions between dust particles and gas molecules are too infrequent to equilibrate these two components. With our 1-D model we show that when dust-gas non-equilibrium physics is included, gas temperatures above 40 km cool and heating rates are reduced. The magnitude of the effect depends mostly on the size and abundance of the dust particles and is proportional to each. With our 3-D model we show that this physics is important mainly during times of intense dust lifting events such as local rocket storms, or regional or global storms when dust quickly penetrates to high altitudes and particle sizes can be somewhat larger at least initially. During such times upper atmosphere temperatures cool, wind systems are weakened, and vertical and meridional transport is diminished when compared to simulation assuming thermal equilibrium.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"429 ","pages":"Article 116452"},"PeriodicalIF":2.5,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.icarus.2024.116451
Ari Essunfeld , Jade M. Comellas , Reid A. Morris , Patrick J. Gasda , Dorothea Delapp , Diane Oyen , Candice C. Bedford , Benton C. Clark , Erwin Dehouck , Ryan B. Anderson , Ana Lomashvili , Roger C. Wiens , Samuel M. Clegg , Olivier Gasnault , Nina L. Lanza
Classifying images is particularly challenging when working with large datasets without predefined groups. We present a new method for grouping images by visual similarity using relatively simple terminology and apply this method to the process of grouping NASA Curiosity rover ChemCam target images into visually similar groups. This method is designed for offline use, rather than on-board applications where power constraints are a consideration. Given the large quantity of data from ChemCam, we narrow the scope of our study to consider only rock targets that are early-mission and contain elevated manganese. A standard list of visual attributes is assessed for each target, and for each attribute on the list, a 1 is recorded if the ChemCam target image exhibits the attribute, and a 0 otherwise. The binary number resulting from this analysis encodes the visual characteristics of each image and is also used to determine similarity between images. Images are modeled as nodes in a network, and similarities between images are modeled as edges between nodes in the network. We find that when using a conservative threshold for similarity and an undirected, unweighted graph to represent the network, visually similar images cluster effectively into disjoint connected components. To improve the geologic usefulness of the resulting target groupings, we define a metric for weak component connectivity and explore methods for automatically partitioning weakly connected components. We compare these results to weighted-graph approaches, as well as to control tests using random partitions. Starting with a dataset of 201 ChemCam Remote Micro Imager mosaics, we found that the “automatic partitioning” method divided these images into 13 groups and resulted in better intra-group visual coherence than the other methods assessed. These results may be applied to motivate machine learning models for automatic attribute recognition to expand data labeling, as well as future classification efforts, including citizen science endeavors.
{"title":"Attribute recognition: A new method for grouping planetary images by visual characteristics, using the example of Mn-rich rocks in the floor of Gale crater, Mars","authors":"Ari Essunfeld , Jade M. Comellas , Reid A. Morris , Patrick J. Gasda , Dorothea Delapp , Diane Oyen , Candice C. Bedford , Benton C. Clark , Erwin Dehouck , Ryan B. Anderson , Ana Lomashvili , Roger C. Wiens , Samuel M. Clegg , Olivier Gasnault , Nina L. Lanza","doi":"10.1016/j.icarus.2024.116451","DOIUrl":"10.1016/j.icarus.2024.116451","url":null,"abstract":"<div><div>Classifying images is particularly challenging when working with large datasets without predefined groups. We present a new method for grouping images by visual similarity using relatively simple terminology and apply this method to the process of grouping NASA <em>Curiosity</em> rover ChemCam target images into visually similar groups. This method is designed for offline use, rather than on-board applications where power constraints are a consideration. Given the large quantity of data from ChemCam, we narrow the scope of our study to consider only rock targets that are early-mission and contain elevated manganese. A standard list of visual attributes is assessed for each target, and for each attribute on the list, a 1 is recorded if the ChemCam target image exhibits the attribute, and a 0 otherwise. The binary number resulting from this analysis encodes the visual characteristics of each image and is also used to determine similarity between images. Images are modeled as nodes in a network, and similarities between images are modeled as edges between nodes in the network. We find that when using a conservative threshold for similarity and an undirected, unweighted graph to represent the network, visually similar images cluster effectively into disjoint connected components. To improve the geologic usefulness of the resulting target groupings, we define a metric for weak component connectivity and explore methods for automatically partitioning weakly connected components. We compare these results to weighted-graph approaches, as well as to control tests using random partitions. Starting with a dataset of 201 ChemCam Remote Micro Imager mosaics, we found that the “automatic partitioning” method divided these images into 13 groups and resulted in better intra-group visual coherence than the other methods assessed. These results may be applied to motivate machine learning models for automatic attribute recognition to expand data labeling, as well as future classification efforts, including citizen science endeavors.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"429 ","pages":"Article 116451"},"PeriodicalIF":2.5,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-28DOI: 10.1016/j.icarus.2024.116453
L.M. Trafton, K.F. Kaplan
Ground-based near-IR observations have revealed that Uranus' anomalously hot upper atmosphere, detected by Voyager II, has been steadily cooling. The observed H3+ and H2 emission-line spectra probe Uranus' ionosphere and thermosphere, respectively. Previous observations have shown that the cooling has continued well past the 2007 vernal equinox, when the seasonal solar forcing turned positive, resulting in net heating of the IAU northern hemisphere. Most of them, especially for H2, were obtained at moderate spectral resolution, R ∼ 1000 to 3000, which admits more sky background, with its associated noise, per spectral resolution element relative to spectrographs having higher spectral resolution. We report the first instance of high spectral resolution being used to observe Uranus' fundamental-band rovibrational quadrupole H2 emission spectrum; where the sky background is suppressed and narrow planetary emission lines stand out against the planetary continuum. The IGRINS spectrograph with spectral resolution R ∼ 45,000 was used to observe Uranus in the K-band on Oct 26 & 27, 2018 at the Lowell Discovery Telescope, and on Nov 27, 2023 at Gemini South. These observations reveal rovibrational temperatures of Uranus' thermosphere of 542 ± 25 K and 397 ± 32 K at these two epochs, respectively. The consecutive-nights at elevated temperature observed at the Discovery Telescope suggest that Uranus' near-IR H2 aurora was detected over each of the northern and southern magnetic poles, respectively. The collective IGRINS results support the continued cooling of Uranus' thermosphere through the 2023 apparition, 73 % through the spring season.
{"title":"High spectral resolution observations of Uranus' near-IR thermospheric H2 emission spectrum using the IGRINS spectrograph during the 2018 and 2023 apparitions","authors":"L.M. Trafton, K.F. Kaplan","doi":"10.1016/j.icarus.2024.116453","DOIUrl":"10.1016/j.icarus.2024.116453","url":null,"abstract":"<div><div>Ground-based near-IR observations have revealed that Uranus' anomalously hot upper atmosphere, detected by Voyager II, has been steadily cooling. The observed H<sub>3</sub><sup>+</sup> and H<sub>2</sub> emission-line spectra probe Uranus' ionosphere and thermosphere, respectively. Previous observations have shown that the cooling has continued well past the 2007 vernal equinox, when the seasonal solar forcing turned positive, resulting in net heating of the IAU northern hemisphere. Most of them, especially for H<sub>2</sub>, were obtained at moderate spectral resolution, R ∼ 1000 to 3000, which admits more sky background, with its associated noise, per spectral resolution element relative to spectrographs having higher spectral resolution. We report the first instance of high spectral resolution being used to observe Uranus' fundamental-band rovibrational quadrupole H<sub>2</sub> emission spectrum; where the sky background is suppressed and narrow planetary emission lines stand out against the planetary continuum. The IGRINS spectrograph with spectral resolution R ∼ 45,000 was used to observe Uranus in the K-band on Oct 26 & 27, 2018 at the Lowell Discovery Telescope, and on Nov 27, 2023 at Gemini South. These observations reveal rovibrational temperatures of Uranus' thermosphere of 542 ± 25 K and 397 ± 32 K at these two epochs, respectively. The consecutive-nights at elevated temperature observed at the Discovery Telescope suggest that Uranus' near-IR H<sub>2</sub> aurora was detected over each of the northern and southern magnetic poles, respectively. The collective IGRINS results support the continued cooling of Uranus' thermosphere through the 2023 apparition, 73 % through the spring season.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"429 ","pages":"Article 116453"},"PeriodicalIF":2.5,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-28DOI: 10.1016/j.icarus.2024.116443
Laura Inno , Margherita Scuderi , Ivano Bertini , Marco Fulle , Elena Mazzotta Epifani , Vincenzo Della Corte , Alice Maria Piccirillo , Antonio Vanzanella , Pedro Lacerda , Chiara Grappasonni , Eleonora Ammanito , Giuseppe Sindoni , Alessandra Rotundi
Among solar system objects, comets coming from the Oort Cloud are an elusive population, intrinsically rare and difficult to detect. Nonetheless, as the more pristine objects we can observe, they encapsulate critical cues on the formation of planetary systems and are the focus of many scientific investigations and science missions. The Legacy Survey of Space and Time (LSST), which will start to operate from the Vera C. Rubin Observatory in 2025, is expected to dramatically improve our detection ability of these comets by performing regular monitoring of the Southern sky deep down to magnitude 24.5 with excellent astrometry. However, making straightforward predictions on future LSST detection rates is challenging due to our biased knowledge of the underlying population. This is because identifications to date have been conducted by various surveys or individual observers, often without detailed information on their respective selection functions. Recent efforts (see e.g. Vokrouhlickỳ et al., 2019) to predict incoming flux of Long Period Comets still suffer of the lack of systematic, well-characterized, homogeneous cometary surveys. Here, we adopt a different point of view by asking how much earlier on known comets on long-period or hyperbolic orbits would have been discovered by a LSST-like survey if it was already in place 10 years prior to their perihelion epoch. In this case, we are not simulating a real flux of incoming comet, as all comets in our sample reach the perihelion simultaneously, but we can analyze the impact of a LSST-like survey on individual objects. We find that LSST would have found about 40% of comets in our sample at least 5 years prior to their perihelion epoch, and at double (at least) the distance at which they were actually discovered. Based on this approach, we find that LSST has the potentiality to at least twofold the current discovery rate of long-period and hyperbolic comets.
{"title":"How much earlier would LSST have discovered currently known long-period comets?","authors":"Laura Inno , Margherita Scuderi , Ivano Bertini , Marco Fulle , Elena Mazzotta Epifani , Vincenzo Della Corte , Alice Maria Piccirillo , Antonio Vanzanella , Pedro Lacerda , Chiara Grappasonni , Eleonora Ammanito , Giuseppe Sindoni , Alessandra Rotundi","doi":"10.1016/j.icarus.2024.116443","DOIUrl":"10.1016/j.icarus.2024.116443","url":null,"abstract":"<div><div>Among solar system objects, comets coming from the Oort Cloud are an elusive population, intrinsically rare and difficult to detect. Nonetheless, as the more pristine objects we can observe, they encapsulate critical cues on the formation of planetary systems and are the focus of many scientific investigations and science missions. The Legacy Survey of Space and Time (LSST), which will start to operate from the Vera C. Rubin Observatory in 2025, is expected to dramatically improve our detection ability of these comets by performing regular monitoring of the Southern sky deep down to magnitude 24.5 with excellent astrometry. However, making straightforward predictions on future LSST detection rates is challenging due to our biased knowledge of the underlying population. This is because identifications to date have been conducted by various surveys or individual observers, often without detailed information on their respective selection functions. Recent efforts (see e.g. Vokrouhlickỳ et al., 2019) to predict incoming flux of Long Period Comets still suffer of the lack of systematic, well-characterized, homogeneous cometary surveys. Here, we adopt a different point of view by asking how much earlier on known comets on long-period or hyperbolic orbits would have been discovered by a LSST-like survey if it was already in place 10 years prior to their perihelion epoch. In this case, we are not simulating a real flux of incoming comet, as all comets in our sample reach the perihelion simultaneously, but we can analyze the impact of a LSST-like survey on individual objects. We find that LSST would have found about 40% of comets in our sample at least 5 years prior to their perihelion epoch, and at double (at least) the distance at which they were actually discovered. Based on this approach, we find that LSST has the potentiality to at least twofold the current discovery rate of long-period and hyperbolic comets.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"429 ","pages":"Article 116443"},"PeriodicalIF":2.5,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-27DOI: 10.1016/j.icarus.2024.116441
T. Gastine , B. Favier
A better understanding of the ice-ocean couplings is required to better characterise the hydrosphere of the icy moons. Using global numerical simulations in spherical geometry, we have investigated here the interplay between rotating convection and a melting boundary. To do so, we have implemented and validated a phase field formulation in the open-source code MagIC. We have conducted a parameter study varying the influence of rotation, the vigour of the convective forcing and the melting temperature. We have evidenced different regimes akin to those already found in previous monophasic models in which the mean axisymmetric ice crust transits from pole-ward thinning to equator-ward thinning with the increase of the rotational constraint on the flow. The derivation of a perturbative model of heat conduction in the ice layer enabled us to relate those mean topographic changes to the underlying latitudinal heat flux variations at the top of the ocean. The phase change has also been found to yield the formation of sizeable non-axisymmetric topography at the solid–liquid interface with a typical size close to that of the convective columns. We have shown that the typical evolution timescale of the interface increases linearly with the crest-to-trough amplitude and quadratically with the mean melt radius. In the case of the largest topographic changes, the convective flows become quasi locked in the topography due to the constructive coupling between convection and ice melting. The tentative extrapolation to the planetary regimes yields meters for the amplitude of non-axisymmetric topography at the base of the ice layer of Enceladus and meters for Titan.
{"title":"Rotating convection with a melting boundary: An application to the icy moons","authors":"T. Gastine , B. Favier","doi":"10.1016/j.icarus.2024.116441","DOIUrl":"10.1016/j.icarus.2024.116441","url":null,"abstract":"<div><div>A better understanding of the ice-ocean couplings is required to better characterise the hydrosphere of the icy moons. Using global numerical simulations in spherical geometry, we have investigated here the interplay between rotating convection and a melting boundary. To do so, we have implemented and validated a phase field formulation in the open-source code <span>MagIC</span>. We have conducted a parameter study varying the influence of rotation, the vigour of the convective forcing and the melting temperature. We have evidenced different regimes akin to those already found in previous monophasic models in which the mean axisymmetric ice crust transits from pole-ward thinning to equator-ward thinning with the increase of the rotational constraint on the flow. The derivation of a perturbative model of heat conduction in the ice layer enabled us to relate those mean topographic changes to the underlying latitudinal heat flux variations at the top of the ocean. The phase change has also been found to yield the formation of sizeable non-axisymmetric topography at the solid–liquid interface with a typical size close to that of the convective columns. We have shown that the typical evolution timescale of the interface increases linearly with the crest-to-trough amplitude and quadratically with the mean melt radius. In the case of the largest topographic changes, the convective flows become quasi locked in the topography due to the constructive coupling between convection and ice melting. The tentative extrapolation to the planetary regimes yields <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>2</mn></mrow></msup><mo>−</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>3</mn></mrow></msup><mo>)</mo></mrow></mrow></math></span> meters for the amplitude of non-axisymmetric topography at the base of the ice layer of Enceladus and <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>3</mn></mrow></msup><mo>−</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>4</mn></mrow></msup><mo>)</mo></mrow></mrow></math></span> meters for Titan.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"429 ","pages":"Article 116441"},"PeriodicalIF":2.5,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-24DOI: 10.1016/j.icarus.2024.116444
Ian Chow , Peter G. Brown
Numerous decameter-sized asteroids have been observed impacting Earth as fireballs. These objects can have impact energies equivalent to hundreds of kilotons of TNT, posing a hazard if they impact populated areas. Previous estimates of meteoroid flux using fireball observations have shown an Earth impact rate for decameter-size objects of about once every 2–3 years. In contrast, telescopic estimates of the near-Earth asteroid population predict the impact rate of such objects to be of order 20–40 years, an order-of-magnitude difference. While the cause of this discrepancy remains unclear, tidal disruption of a larger near-Earth body has been proposed as an explanation for these excess decameter-sized impactors. The release in 2022 of previously classified United States Government (USG) satellite sensor data for fireball events has provided a wealth of new information on many of these impacts. Using this newly available USG sensor data, we present the first population-level study characterizing the orbital and dynamical properties of 14 decameter-sized Earth impactors detected by USG sensors since 1994, with a particular focus on searching for evidence of tidal disruption as the cause of the impact rate discrepancy. We find there is no evidence for recent ( years) tidal disruption and weak evidence for longer-term tidal disruption in the decameter impactor population, but that the latter conclusion is limited by small number statistics. We also investigate the origins of both the impactor and near-Earth asteroid populations of decameter-sized objects from the main asteroid belt. We find that both populations generally originate from the same source regions: primarily from the secular resonance (%) with small contributions from the Hungaria group (%) and the 3:1 Jupiter mean-motion resonance (%).
{"title":"Decameter-sized Earth impactors – I: Orbital properties","authors":"Ian Chow , Peter G. Brown","doi":"10.1016/j.icarus.2024.116444","DOIUrl":"10.1016/j.icarus.2024.116444","url":null,"abstract":"<div><div>Numerous decameter-sized asteroids have been observed impacting Earth as fireballs. These objects can have impact energies equivalent to hundreds of kilotons of TNT, posing a hazard if they impact populated areas. Previous estimates of meteoroid flux using fireball observations have shown an Earth impact rate for decameter-size objects of about once every 2–3 years. In contrast, telescopic estimates of the near-Earth asteroid population predict the impact rate of such objects to be of order 20–40 years, an order-of-magnitude difference. While the cause of this discrepancy remains unclear, tidal disruption of a larger near-Earth body has been proposed as an explanation for these excess decameter-sized impactors. The release in 2022 of previously classified United States Government (USG) satellite sensor data for fireball events has provided a wealth of new information on many of these impacts. Using this newly available USG sensor data, we present the first population-level study characterizing the orbital and dynamical properties of 14 decameter-sized Earth impactors detected by USG sensors since 1994, with a particular focus on searching for evidence of tidal disruption as the cause of the impact rate discrepancy. We find there is no evidence for recent (<span><math><mrow><mo>≲</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>4</mn></mrow></msup></mrow></math></span> years) tidal disruption and weak evidence for longer-term tidal disruption in the decameter impactor population, but that the latter conclusion is limited by small number statistics. We also investigate the origins of both the impactor and near-Earth asteroid populations of decameter-sized objects from the main asteroid belt. We find that both populations generally originate from the same source regions: primarily from the <span><math><msub><mrow><mi>ν</mi></mrow><mrow><mn>6</mn></mrow></msub></math></span> secular resonance (<span><math><mrow><mo>∼</mo><mn>70</mn></mrow></math></span>%) with small contributions from the Hungaria group (<span><math><mrow><mo>∼</mo><mn>20</mn></mrow></math></span>%) and the 3:1 Jupiter mean-motion resonance (<span><math><mrow><mo>∼</mo><mn>10</mn></mrow></math></span>%).</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"429 ","pages":"Article 116444"},"PeriodicalIF":2.5,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-24DOI: 10.1016/j.icarus.2024.116442
C.D. Schultz, R.E. Milliken
The scarcity of olivine-rich mantle material in meteorite collections and asteroid spectra, known as the “Missing Mantle Conundrum,” challenges our understanding of planetesimal differentiation. Current models suggest that numerous planetesimals underwent melting and differentiation early in Solar System history, yet little evidence of olivine- and pyroxene-rich mantles is found. We explore the hypothesis that mantle material may be present in the asteroid belt but is spectrally masked by dark, primitive carbonaceous chondrite material. To test this, we mixed laboratory analogs of CM and CV chondrite mantle compositions with natural CM2 and CV3 meteorites, examining how particle size and chondritic material abundance affect the detectability of diagnostic silicate absorption features. Visible-near infrared (VNIR) reflectance spectra demonstrate that even small amounts of carbonaceous material can suppress olivine and pyroxene absorption bands. The suppression of absorption features and spectral darkening is highly nonlinear, with this effect being most notable for the finer particles and the CM chondrites. At mantle abundances below 20 wt%, spectral features for all mixtures become virtually indistinguishable from those of the chondrite meteorites. Simulated noise levels typical of ground-based telescopic observations reveal that mantle material can be masked at even higher abundances, potentially obscuring ∼30–65 wt% of mantle material. These findings suggest that significant amounts of olivine- and pyroxene-rich mantle material may be present in near-Earth and main-belt asteroids, currently classified as primitive bodies. Rubble pile asteroids, which are widespread, may be particularly susceptible to misinterpretation due to their complex regolith, where differentiated mantle material can be mixed with primitive, undifferentiated components. This mixing, which arises naturally through the Solar System's ongoing collisional evolution, complicates spectral interpretations and highlights the potential for underestimating the extent of differentiation in these bodies.
{"title":"The curious case of the missing mantle: How carbonaceous chondrites may confound the spectral identification of partially differentiated asteroids","authors":"C.D. Schultz, R.E. Milliken","doi":"10.1016/j.icarus.2024.116442","DOIUrl":"10.1016/j.icarus.2024.116442","url":null,"abstract":"<div><div>The scarcity of olivine-rich mantle material in meteorite collections and asteroid spectra, known as the “Missing Mantle Conundrum,” challenges our understanding of planetesimal differentiation. Current models suggest that numerous planetesimals underwent melting and differentiation early in Solar System history, yet little evidence of olivine- and pyroxene-rich mantles is found. We explore the hypothesis that mantle material may be present in the asteroid belt but is spectrally masked by dark, primitive carbonaceous chondrite material. To test this, we mixed laboratory analogs of CM and CV chondrite mantle compositions with natural CM2 and CV3 meteorites, examining how particle size and chondritic material abundance affect the detectability of diagnostic silicate absorption features. Visible-near infrared (VNIR) reflectance spectra demonstrate that even small amounts of carbonaceous material can suppress olivine and pyroxene absorption bands. The suppression of absorption features and spectral darkening is highly nonlinear, with this effect being most notable for the finer particles and the CM chondrites. At mantle abundances below 20 wt%, spectral features for all mixtures become virtually indistinguishable from those of the chondrite meteorites. Simulated noise levels typical of ground-based telescopic observations reveal that mantle material can be masked at even higher abundances, potentially obscuring ∼30–65 wt% of mantle material. These findings suggest that significant amounts of olivine- and pyroxene-rich mantle material may be present in near-Earth and main-belt asteroids, currently classified as primitive bodies. Rubble pile asteroids, which are widespread, may be particularly susceptible to misinterpretation due to their complex regolith, where differentiated mantle material can be mixed with primitive, undifferentiated components. This mixing, which arises naturally through the Solar System's ongoing collisional evolution, complicates spectral interpretations and highlights the potential for underestimating the extent of differentiation in these bodies.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"429 ","pages":"Article 116442"},"PeriodicalIF":2.5,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-21DOI: 10.1016/j.icarus.2024.116448
Mengfan Qiu , Sen Hu , Huicun He , Zongyu Yue , Hejiu Hui , Jialong Hao , Ruiying Li , Sheng Gou , Lixin Gu , Xu Tang , Jinhua Li , Wei Yang , Hengci Tian , Chi Zhang , Di Zhang , Qian Mao , Lihui Jia , Xiaoguang Li , Yi Chen , Shitou Wu , Fuyuan Wu
Lunar soils contain various types of components and thus are crucial for unraveling the geological and impact histories of the Moon. Little is known about the amount and source regions of the non-mare components preserved in the Chang'e-5 (CE5) lunar soils. A study of systematic identification and characterization of the non-mare components in the CE5 lunar soils was carried out in this work. A non-mare clast, displaying contrast to mare basalts, was firstly identified in the scooped CE5 lunar soils using nondestructive micro-CT investigating. Further detailed petrographic observations and analyses of mineral chemistry reveal that this non-mare clast is a highlands alkali suite (HAS). This HAS clast is mainly composed of plagioclase (46.5), pigeonite (30.9), K-Si-rich mesostasis (17.0), K-felspar (4.12), and silica (0.87) in area%, with minor ilmenite, merrillite, apatite, baddeleyite, and troilite. This clast contains high-pressure polymorph of silica, seifertite and stishovite, and is characterized by high K2O (1.88 wt%), and low TiO2 (0.63 wt%) and low FeO (8.36 wt%) contents. Pb-Pb dating of baddeleyite yields a date of 3913 ± 7 Ma, probably representing a plutonic event or an impact event happened on the Moon. Another ejection event is required to transport the alkali suite to the landing site of the CE5 mission postdated the emplacement of the CE5 mare basalt.
{"title":"Discovery of a highly shocked alkali suite clast in the Chang'e-5 lunar soils","authors":"Mengfan Qiu , Sen Hu , Huicun He , Zongyu Yue , Hejiu Hui , Jialong Hao , Ruiying Li , Sheng Gou , Lixin Gu , Xu Tang , Jinhua Li , Wei Yang , Hengci Tian , Chi Zhang , Di Zhang , Qian Mao , Lihui Jia , Xiaoguang Li , Yi Chen , Shitou Wu , Fuyuan Wu","doi":"10.1016/j.icarus.2024.116448","DOIUrl":"10.1016/j.icarus.2024.116448","url":null,"abstract":"<div><div>Lunar soils contain various types of components and thus are crucial for unraveling the geological and impact histories of the Moon. Little is known about the amount and source regions of the non-mare components preserved in the Chang'e-5 (CE5) lunar soils. A study of systematic identification and characterization of the non-mare components in the CE5 lunar soils was carried out in this work. A non-mare clast, displaying contrast to mare basalts, was firstly identified in the scooped CE5 lunar soils using nondestructive micro-CT investigating. Further detailed petrographic observations and analyses of mineral chemistry reveal that this non-mare clast is a highlands alkali suite (HAS). This HAS clast is mainly composed of plagioclase (46.5), pigeonite (30.9), K-Si-rich mesostasis (17.0), K-felspar (4.12), and silica (0.87) in area%, with minor ilmenite, merrillite, apatite, baddeleyite, and troilite. This clast contains high-pressure polymorph of silica, seifertite and stishovite, and is characterized by high K<sub>2</sub>O (1.88 wt%), and low TiO<sub>2</sub> (0.63 wt%) and low FeO (8.36 wt%) contents. Pb-Pb dating of baddeleyite yields a date of 3913 ± 7 Ma, probably representing a plutonic event or an impact event happened on the Moon. Another ejection event is required to transport the alkali suite to the landing site of the CE5 mission postdated the emplacement of the CE5 mare basalt.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"429 ","pages":"Article 116448"},"PeriodicalIF":2.5,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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