Ramanakumar Sankar, Shawn Brueshaber, Lucy Fortson, Candice Hansen-Koharcheck, Chris Lintott, Kameswara Mantha, Cooper Nesmith and Glenn S. Orton
The Jovian atmosphere contains a wide diversity of vortices, which have a large range of sizes, colors, and forms in different dynamical regimes. The formation processes for these vortices are poorly understood, and aside from a few known, long-lived ovals, such as the Great Red Spot and Oval BA, vortex stability and their temporal evolution are currently largely unknown. In this study, we use JunoCam data and a citizen science project on Zooniverse to derive a catalog of vortices, some with repeated observations, from 2018 May to 2021 September, and we analyze their associated properties, such as size, location, and color. We find that different-colored vortices (binned as white, red, brown, and dark) follow vastly different distributions in terms of their sizes and where they are found on the planet. We employ a simplified stability criterion using these vortices as a proxy, to derive a minimum Rossby deformation length for the planet of ∼1800 km. We find that this value of Ld is largely constant throughout the atmosphere and does not have an appreciable meridional gradient.
{"title":"Jovian Vortex Hunter: A Citizen Science Project to Study Jupiter’s Vortices","authors":"Ramanakumar Sankar, Shawn Brueshaber, Lucy Fortson, Candice Hansen-Koharcheck, Chris Lintott, Kameswara Mantha, Cooper Nesmith and Glenn S. Orton","doi":"10.3847/psj/ad6e75","DOIUrl":"https://doi.org/10.3847/psj/ad6e75","url":null,"abstract":"The Jovian atmosphere contains a wide diversity of vortices, which have a large range of sizes, colors, and forms in different dynamical regimes. The formation processes for these vortices are poorly understood, and aside from a few known, long-lived ovals, such as the Great Red Spot and Oval BA, vortex stability and their temporal evolution are currently largely unknown. In this study, we use JunoCam data and a citizen science project on Zooniverse to derive a catalog of vortices, some with repeated observations, from 2018 May to 2021 September, and we analyze their associated properties, such as size, location, and color. We find that different-colored vortices (binned as white, red, brown, and dark) follow vastly different distributions in terms of their sizes and where they are found on the planet. We employ a simplified stability criterion using these vortices as a proxy, to derive a minimum Rossby deformation length for the planet of ∼1800 km. We find that this value of Ld is largely constant throughout the atmosphere and does not have an appreciable meridional gradient.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"62 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268356","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}
The hypothesized electrostatic lofting of individual regolith grains on the Moon and asteroids has been investigated extensively in laboratory studies. Cohesion may dominate how regolith behaves on these small, airless bodies, yet the magnitude of this force remains uncertain. We induce the electrostatic detachment of dust as a mechanism to break cohesive bonds between individual zirconia-silica microspheres in order to measure the interparticle cohesive force between them, likely dominated by capillary bridges. A high-speed camera imaged centroid positions of the lofted microspheres over time. Using the centroids from the initial detachment, we numerically calculated initial accelerations to solve for the cohesion that had been restraining the microspheres. Unexpectedly, the electrostatic lofting of clumps of particles was observed and experimental results showed that clumps were a nonnegligible portion of the lofted object population.
{"title":"Experimental Method for Measuring Cohesion of Regolith via Electrostatic Lofting","authors":"Charles T. Pett and Christine M. Hartzell","doi":"10.3847/psj/ad6c36","DOIUrl":"https://doi.org/10.3847/psj/ad6c36","url":null,"abstract":"The hypothesized electrostatic lofting of individual regolith grains on the Moon and asteroids has been investigated extensively in laboratory studies. Cohesion may dominate how regolith behaves on these small, airless bodies, yet the magnitude of this force remains uncertain. We induce the electrostatic detachment of dust as a mechanism to break cohesive bonds between individual zirconia-silica microspheres in order to measure the interparticle cohesive force between them, likely dominated by capillary bridges. A high-speed camera imaged centroid positions of the lofted microspheres over time. Using the centroids from the initial detachment, we numerically calculated initial accelerations to solve for the cohesion that had been restraining the microspheres. Unexpectedly, the electrostatic lofting of clumps of particles was observed and experimental results showed that clumps were a nonnegligible portion of the lofted object population.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268357","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}
C. Lantz, T. Nakamura, D. Baklouti, R. Brunetto, E. Henault, S. Kobayashi, O. Mivumbi, Z. Djouadi, E. Quirico, M. Zolensky and T. Hiroi
Remote sensing study of asteroids will soon enter a new era with an increasing amount of data available thanks to the JWST, especially in the mid-infrared (MIR) range that allows identification of mineral species. It will then be possible to establish a taxonomy, as is currently available in the visible–near-infrared range, based on MIR spectral parameters. It had been previously shown that the MIR range is very sensitive to space weathering (SpWe) effects. Thus, it is crucial to determine which spectral changes are involved to disentangle initial composition from surface aging and provide tools to interpret future remote sensing data of asteroids. We present here MIR measurements of a wide variety of ion-irradiated carbonaceous chondrites as a simulation of the solar wind SpWe component. We evaluate several parameters (the Christiansen feature and Reststrahlen band positions, the width of the main Si–O band) and test different measurement conditions (ion energy and geometry of observation). We highlight a dependency of the spectral changes with the initial composition, as hydrated samples are more affected than anhydrous ones. We confirm the role of the geometry in the detection of SpWe effects as already shown in the near-infrared, with a competition effect between the depth probed by photons and the implantation depth of ions (function of the energy used). We will discuss the results in the framework of future observations and Ryugu’s and Bennu’s samples studied in the laboratory.
{"title":"Mid-infrared Measurements of Ion-irradiated Carbonaceous Meteorites: How to Better Detect Space Weathering Effects","authors":"C. Lantz, T. Nakamura, D. Baklouti, R. Brunetto, E. Henault, S. Kobayashi, O. Mivumbi, Z. Djouadi, E. Quirico, M. Zolensky and T. Hiroi","doi":"10.3847/psj/ad5d6f","DOIUrl":"https://doi.org/10.3847/psj/ad5d6f","url":null,"abstract":"Remote sensing study of asteroids will soon enter a new era with an increasing amount of data available thanks to the JWST, especially in the mid-infrared (MIR) range that allows identification of mineral species. It will then be possible to establish a taxonomy, as is currently available in the visible–near-infrared range, based on MIR spectral parameters. It had been previously shown that the MIR range is very sensitive to space weathering (SpWe) effects. Thus, it is crucial to determine which spectral changes are involved to disentangle initial composition from surface aging and provide tools to interpret future remote sensing data of asteroids. We present here MIR measurements of a wide variety of ion-irradiated carbonaceous chondrites as a simulation of the solar wind SpWe component. We evaluate several parameters (the Christiansen feature and Reststrahlen band positions, the width of the main Si–O band) and test different measurement conditions (ion energy and geometry of observation). We highlight a dependency of the spectral changes with the initial composition, as hydrated samples are more affected than anhydrous ones. We confirm the role of the geometry in the detection of SpWe effects as already shown in the near-infrared, with a competition effect between the depth probed by photons and the implantation depth of ions (function of the energy used). We will discuss the results in the framework of future observations and Ryugu’s and Bennu’s samples studied in the laboratory.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268358","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}
Neptune’s moon Triton has two remarkable attributes: its retrograde orbit suggests that it was captured from the Kuiper Belt, and Triton has one of the youngest surfaces of all the icy satellites in the solar system. Soon after capture, Triton experienced strong diurnal tides raised by Neptune, which caused intense deformation, heating, and melting of its ice shell as its highly eccentric initial orbit was circularized. While previous studies have suggested that Triton’s orbit would have circularized early in solar system history, we show that internal feedbacks between tidal heating and ice shell melting significantly reduce the orbital evolution rate, causing strong tidal heating to persist for billions of years. We simulate Triton’s post-capture evolution over a range of initial semimajor axes and ice shell properties. We find that Triton’s ice shell would have been extremely thin (1–10 km) for a period of 1–4 billion years, with tidal stresses strong enough to fracture the entire ice shell down to the subsurface ocean. A final phase of intense geologic activity may have occurred after tidal dissipation waned, in which late-stage ice shell thickening caused ocean pressurization potentially sufficient to refracture the ice shell and push water to the surface. Such overpressurization could have caused recent massive cryovolcanic resurfacing, perhaps explaining Triton’s geologically young surface. It is therefore possible that Triton’s youthful surface and its origin as a captured satellite may in fact be related. A long-lived subsurface ocean and extended thin ice shell period also greatly increase Triton’s astrobiological potential.
{"title":"Triton’s Captured Youth: Tidal Heating Kept Triton Warm and Active for Billions of Years","authors":"N. P. Hammond and G. C. Collins","doi":"10.3847/psj/ad6744","DOIUrl":"https://doi.org/10.3847/psj/ad6744","url":null,"abstract":"Neptune’s moon Triton has two remarkable attributes: its retrograde orbit suggests that it was captured from the Kuiper Belt, and Triton has one of the youngest surfaces of all the icy satellites in the solar system. Soon after capture, Triton experienced strong diurnal tides raised by Neptune, which caused intense deformation, heating, and melting of its ice shell as its highly eccentric initial orbit was circularized. While previous studies have suggested that Triton’s orbit would have circularized early in solar system history, we show that internal feedbacks between tidal heating and ice shell melting significantly reduce the orbital evolution rate, causing strong tidal heating to persist for billions of years. We simulate Triton’s post-capture evolution over a range of initial semimajor axes and ice shell properties. We find that Triton’s ice shell would have been extremely thin (1–10 km) for a period of 1–4 billion years, with tidal stresses strong enough to fracture the entire ice shell down to the subsurface ocean. A final phase of intense geologic activity may have occurred after tidal dissipation waned, in which late-stage ice shell thickening caused ocean pressurization potentially sufficient to refracture the ice shell and push water to the surface. Such overpressurization could have caused recent massive cryovolcanic resurfacing, perhaps explaining Triton’s geologically young surface. It is therefore possible that Triton’s youthful surface and its origin as a captured satellite may in fact be related. A long-lived subsurface ocean and extended thin ice shell period also greatly increase Triton’s astrobiological potential.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268359","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}
Roger N. Clark, Neil C. Pearson, Thomas B. McCord, Deborah L. Domingue, Keith Eric Livo, Joseph W. Boardman, Daniel P. Moriarty, Amanda R. Hendrix, Georgiana Kramer and Maria E. Banks
The Moon Mineralogy Mapper (M3) on the Chandrayaan-1 spacecraft provided nearly global 0.5–3 μm imaging-spectroscopy data at 140 m pixel–1 in 85 spectral bands. Targeted locations were imaged at 70 m pixel–1 and higher spectral resolution. These data enable a detailed look at the mineralogy, hydroxyl, and water signatures exposed on the lunar surface. We find evidence for multiple processes, including probable solar wind implantation, excavation of hydroxyl-poor and water-poor material in cratering events, excavation of hydroxyl and water-rich materials from depth and global trends with rock type and latitude. Some water-rich areas display sharp boundaries with water-poor rocks but have a diffuse halo of hydroxyl surrounding the water-rich rocks indicating a weathering process of destruction of water, probably due to a regolith gardening process. Mapping for specific mineralogy shows evidence for absorptions near 2.2 μm, probably associated with smectites, and near 1.9 μm due to water. Lunar swirls are confirmed to be OH-poor, but we also find evidence that swirls are water-poor based on a weak 1.9 μm water band. Some swirls show enhanced pyroxene absorption. “Diurnal” signatures are found with stable minerals. Pyroxene is shown to exhibit strong band depth changes with the diurnal cycle, which directly tracks the solar incidence angle and is consistent with changing composition and/or grain size with depth. Mapping of M3 data for the presence of iron oxides (e.g., hematite and goethite) is found to be a false signature in the M3 data due to scattered light in the instrument.
{"title":"The Global Distribution of Water and Hydroxyl on the Moon as Seen by the Moon Mineralogy Mapper (M3)","authors":"Roger N. Clark, Neil C. Pearson, Thomas B. McCord, Deborah L. Domingue, Keith Eric Livo, Joseph W. Boardman, Daniel P. Moriarty, Amanda R. Hendrix, Georgiana Kramer and Maria E. Banks","doi":"10.3847/psj/ad5837","DOIUrl":"https://doi.org/10.3847/psj/ad5837","url":null,"abstract":"The Moon Mineralogy Mapper (M3) on the Chandrayaan-1 spacecraft provided nearly global 0.5–3 μm imaging-spectroscopy data at 140 m pixel–1 in 85 spectral bands. Targeted locations were imaged at 70 m pixel–1 and higher spectral resolution. These data enable a detailed look at the mineralogy, hydroxyl, and water signatures exposed on the lunar surface. We find evidence for multiple processes, including probable solar wind implantation, excavation of hydroxyl-poor and water-poor material in cratering events, excavation of hydroxyl and water-rich materials from depth and global trends with rock type and latitude. Some water-rich areas display sharp boundaries with water-poor rocks but have a diffuse halo of hydroxyl surrounding the water-rich rocks indicating a weathering process of destruction of water, probably due to a regolith gardening process. Mapping for specific mineralogy shows evidence for absorptions near 2.2 μm, probably associated with smectites, and near 1.9 μm due to water. Lunar swirls are confirmed to be OH-poor, but we also find evidence that swirls are water-poor based on a weak 1.9 μm water band. Some swirls show enhanced pyroxene absorption. “Diurnal” signatures are found with stable minerals. Pyroxene is shown to exhibit strong band depth changes with the diurnal cycle, which directly tracks the solar incidence angle and is consistent with changing composition and/or grain size with depth. Mapping of M3 data for the presence of iron oxides (e.g., hematite and goethite) is found to be a false signature in the M3 data due to scattered light in the instrument.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268360","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}
Vincent Kofman, Geronimo Luis Villanueva, Thomas J. Fauchez, Avi M. Mandell, Ted M. Johnson, Allison Payne, Natasha Latouf and Soumil Kelkar
The atmospheres and surfaces of planets show a tremendous amount of spatial variation, which has a direct effect on the spectrum of the object, even if this may not be spatially resolved. Here, we apply hyperrealistic radiative simulations of Earth as an exoplanet comprising thousands of simulations and study the unresolved spectrum. The GlobES module on the Planetary Spectrum Generator was used, and we parameterized the atmosphere as described in the modern-Earth retrospective analysis for research and applications (MERRA-2) database. The simulations were made into high spatial resolution images and compared to space-based observations from the DSCOVR/EPIC (L1) and Himawari-8 (geostationary) satellites, confirming spatial variations and the spectral intensities of the simulations. The DISCOVR/EPIC camera only functions in narrow wavelength bands, but strong agreement is demonstrated. It is shown that aerosols and small particles play an important role in defining Earth’s reflectance spectra, contributing significantly to its characteristic blue color. Subsequently, a comprehensive noise model is employed to constrain the exposure time required to detect O2, O3, and H2O as a function of varying ground and cloud cover for several concept observatories, including the Habitable Worlds Observatory (HWO). Cloud coverage enhances the detectability of planets in reflected light, with important consequences for the design of the future HWO. The HWO concept would require between 3 and 10 times longer to observe the studied features than LUVOIR A but performs better than the HabEx without a starshade. The codes, routines, and noise models are made publicly available.
{"title":"The Pale Blue Dot: Using the Planetary Spectrum Generator to Simulate Signals from Hyperrealistic Exo-Earths","authors":"Vincent Kofman, Geronimo Luis Villanueva, Thomas J. Fauchez, Avi M. Mandell, Ted M. Johnson, Allison Payne, Natasha Latouf and Soumil Kelkar","doi":"10.3847/psj/ad6448","DOIUrl":"https://doi.org/10.3847/psj/ad6448","url":null,"abstract":"The atmospheres and surfaces of planets show a tremendous amount of spatial variation, which has a direct effect on the spectrum of the object, even if this may not be spatially resolved. Here, we apply hyperrealistic radiative simulations of Earth as an exoplanet comprising thousands of simulations and study the unresolved spectrum. The GlobES module on the Planetary Spectrum Generator was used, and we parameterized the atmosphere as described in the modern-Earth retrospective analysis for research and applications (MERRA-2) database. The simulations were made into high spatial resolution images and compared to space-based observations from the DSCOVR/EPIC (L1) and Himawari-8 (geostationary) satellites, confirming spatial variations and the spectral intensities of the simulations. The DISCOVR/EPIC camera only functions in narrow wavelength bands, but strong agreement is demonstrated. It is shown that aerosols and small particles play an important role in defining Earth’s reflectance spectra, contributing significantly to its characteristic blue color. Subsequently, a comprehensive noise model is employed to constrain the exposure time required to detect O2, O3, and H2O as a function of varying ground and cloud cover for several concept observatories, including the Habitable Worlds Observatory (HWO). Cloud coverage enhances the detectability of planets in reflected light, with important consequences for the design of the future HWO. The HWO concept would require between 3 and 10 times longer to observe the studied features than LUVOIR A but performs better than the HabEx without a starshade. The codes, routines, and noise models are made publicly available.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268362","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}
Patrick O’Brien, Jennifer E. C. Scully, Margaret E. Landis, Norbert Schörghofer and Paul O. Hayne
On icy bodies like the dwarf planet Ceres, impacts excavate volatile-rich material from beneath a dessicated lag layer and deposit it in the near-surface environment where higher temperatures drive sublimation. Ice has been detected in the upper meter of the ejecta blanket and interior of Occator crater, suggesting that large craters could be a significant source of exospheric water vapor. We assess the present-day exospheric contribution of a complex crater by first estimating the extent of volatile-rich deposits associated with a crater of a given size. We use a vapor diffusion model to calculate sublimation rates from the deposits, taking into account constraints on the thermophysical parameters of icy regolith from the Dawn mission. Extrapolating this model to craters formed throughout Ceres’ history, we find that the cumulative present-day sublimation rate from all complex crater deposits is ∼0.01 kg s−1, a factor of a few times greater than the outgassing rate from the global ice table. The dominant source of sublimation is not the conspicuous faculae but rather the volatile-rich ejecta blankets, which cover a significantly larger area than deposits in the crater interior. Because large impacts can blanket a significant fraction of the surface with ice-rich ejecta, complex craters are crucial for understanding the background present-day exosphere and the history of sublimation on icy bodies.
{"title":"Enhancement of the Cerean Exosphere by Sublimation from Complex Craters","authors":"Patrick O’Brien, Jennifer E. C. Scully, Margaret E. Landis, Norbert Schörghofer and Paul O. Hayne","doi":"10.3847/psj/ad60c9","DOIUrl":"https://doi.org/10.3847/psj/ad60c9","url":null,"abstract":"On icy bodies like the dwarf planet Ceres, impacts excavate volatile-rich material from beneath a dessicated lag layer and deposit it in the near-surface environment where higher temperatures drive sublimation. Ice has been detected in the upper meter of the ejecta blanket and interior of Occator crater, suggesting that large craters could be a significant source of exospheric water vapor. We assess the present-day exospheric contribution of a complex crater by first estimating the extent of volatile-rich deposits associated with a crater of a given size. We use a vapor diffusion model to calculate sublimation rates from the deposits, taking into account constraints on the thermophysical parameters of icy regolith from the Dawn mission. Extrapolating this model to craters formed throughout Ceres’ history, we find that the cumulative present-day sublimation rate from all complex crater deposits is ∼0.01 kg s−1, a factor of a few times greater than the outgassing rate from the global ice table. The dominant source of sublimation is not the conspicuous faculae but rather the volatile-rich ejecta blankets, which cover a significantly larger area than deposits in the crater interior. Because large impacts can blanket a significant fraction of the surface with ice-rich ejecta, complex craters are crucial for understanding the background present-day exosphere and the history of sublimation on icy bodies.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268361","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}
Lauren E. Mc Keown, Michael J. Poston, Serina Diniega, Ganna Portyankina, Candice J. Hansen, Klaus-Michael Aye, Elizabeth M. Carey, Jennifer E. C. Scully, Sylvain Piqueux, Lori R. Shiraishi and Sarah N. Cruz
The Kieffer model is a widely accepted explanation for seasonal modification of the Martian surface by CO2 ice sublimation and the formation of a “zoo” of intriguing surface features. However, the lack of in situ observations and empirical laboratory measurements of Martian winter conditions hampers model validation and refinement. We present the first experiments to investigate all three main stages of the Kieffer model within a single experiment: (i) CO2 condensation on a thick layer of Mars regolith simulant; (ii) sublimation of CO2 ice and plume, spot, and halo formation; and (iii) the resultant formation of surface features. We find that the full Kieffer model is supported on the laboratory scale as (i) CO2 diffuses into the regolith pore spaces and forms a thin overlying conformal layer of translucent ice. When a buried heater is activated, (ii) a plume and dark spot develop as dust is ejected with pressurized gas, and the falling dust creates a bright halo. During plume activity, (iii) thermal stress cracks form in a network similar in morphology to certain types of spiders, dendritic troughs, furrows, and patterned ground in the Martian high south polar latitudes. These cracks appear to form owing to sublimation of CO2within the substrate, instead of surface scouring. We discuss the potential for this process to be an alternative formation mechanism for “cracked” spider-like morphologies on Mars. Leveraging our laboratory observations, we also provide guidance for future laboratory or in situ investigations of the three stages of the Kieffer model.
{"title":"A Lab-scale Investigation of the Mars Kieffer Model","authors":"Lauren E. Mc Keown, Michael J. Poston, Serina Diniega, Ganna Portyankina, Candice J. Hansen, Klaus-Michael Aye, Elizabeth M. Carey, Jennifer E. C. Scully, Sylvain Piqueux, Lori R. Shiraishi and Sarah N. Cruz","doi":"10.3847/psj/ad67c8","DOIUrl":"https://doi.org/10.3847/psj/ad67c8","url":null,"abstract":"The Kieffer model is a widely accepted explanation for seasonal modification of the Martian surface by CO2 ice sublimation and the formation of a “zoo” of intriguing surface features. However, the lack of in situ observations and empirical laboratory measurements of Martian winter conditions hampers model validation and refinement. We present the first experiments to investigate all three main stages of the Kieffer model within a single experiment: (i) CO2 condensation on a thick layer of Mars regolith simulant; (ii) sublimation of CO2 ice and plume, spot, and halo formation; and (iii) the resultant formation of surface features. We find that the full Kieffer model is supported on the laboratory scale as (i) CO2 diffuses into the regolith pore spaces and forms a thin overlying conformal layer of translucent ice. When a buried heater is activated, (ii) a plume and dark spot develop as dust is ejected with pressurized gas, and the falling dust creates a bright halo. During plume activity, (iii) thermal stress cracks form in a network similar in morphology to certain types of spiders, dendritic troughs, furrows, and patterned ground in the Martian high south polar latitudes. These cracks appear to form owing to sublimation of CO2within the substrate, instead of surface scouring. We discuss the potential for this process to be an alternative formation mechanism for “cracked” spider-like morphologies on Mars. Leveraging our laboratory observations, we also provide guidance for future laboratory or in situ investigations of the three stages of the Kieffer model.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142200953","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}
Marc W. Buie, John R. Spencer, Simon B. Porter, Susan D. Benecchi, Alex H. Parker, S. Alan Stern, Michael Belton, Richard P. Binzel, David Borncamp, Francesca DeMeo, S. Fabbro, Cesar Fuentes, Hisanori Furusawa, Tetsuharu Fuse, Pamela L. Gay, Stephen Gwyn, Matthew J. Holman, H. Karoji, J. J. Kavelaars, Daisuke Kinoshita, Satoshi Miyazaki, Matt Mountain, Keith S. Noll, David J. Osip, Jean-Marc Petit, Neill I. Reid, Scott S. Sheppard, Mark Showalter, Andrew J. Steffl, Ray E. Sterner, Akito Tajitsu, David J. Tholen, David E. Trilling, Harold A. Weaver, Anne J. Verbiscer, Lawrence H. Wasserman, Takuji Yamashita, Toshifumi Yanagisawa, Fumi Yoshida and Amanda M. Zangari
Following the Pluto flyby of the New Horizons spacecraft, the mission provided a unique opportunity to explore the Kuiper Belt in situ. The possibility existed to fly by a Kuiper Belt object (KBO), as well as to observe additional objects at distances closer than are feasible from Earth-orbit facilities. However, at the time of launch no KBOs were known about that were accessible by the spacecraft. In this paper we present the results of 10 yr of observations and three uniquely dedicated efforts—two ground-based using the Subaru Suprime Camera, the Magellan MegaCam and IMACS Cameras, and one with the Hubble Space Telescope—to find such KBOs for study. In this paper we overview the search criteria and strategies employed in our work and detail the analysis efforts to locate and track faint objects in the Galactic plane. We also present a summary of all of the KBOs that were discovered as part of our efforts and how spacecraft targetability was assessed, including a detailed description of our astrometric analysis, which included development of an extensive secondary calibration network. Overall, these efforts resulted in the discovery of 85 KBOs, including 11 that became objects for distant observation by New Horizons and (486958) Arrokoth, which became the first post-Pluto flyby destination.
{"title":"The New Horizons Extended Mission Target: Arrokoth Search and Discovery","authors":"Marc W. Buie, John R. Spencer, Simon B. Porter, Susan D. Benecchi, Alex H. Parker, S. Alan Stern, Michael Belton, Richard P. Binzel, David Borncamp, Francesca DeMeo, S. Fabbro, Cesar Fuentes, Hisanori Furusawa, Tetsuharu Fuse, Pamela L. Gay, Stephen Gwyn, Matthew J. Holman, H. Karoji, J. J. Kavelaars, Daisuke Kinoshita, Satoshi Miyazaki, Matt Mountain, Keith S. Noll, David J. Osip, Jean-Marc Petit, Neill I. Reid, Scott S. Sheppard, Mark Showalter, Andrew J. Steffl, Ray E. Sterner, Akito Tajitsu, David J. Tholen, David E. Trilling, Harold A. Weaver, Anne J. Verbiscer, Lawrence H. Wasserman, Takuji Yamashita, Toshifumi Yanagisawa, Fumi Yoshida and Amanda M. Zangari","doi":"10.3847/psj/ad676d","DOIUrl":"https://doi.org/10.3847/psj/ad676d","url":null,"abstract":"Following the Pluto flyby of the New Horizons spacecraft, the mission provided a unique opportunity to explore the Kuiper Belt in situ. The possibility existed to fly by a Kuiper Belt object (KBO), as well as to observe additional objects at distances closer than are feasible from Earth-orbit facilities. However, at the time of launch no KBOs were known about that were accessible by the spacecraft. In this paper we present the results of 10 yr of observations and three uniquely dedicated efforts—two ground-based using the Subaru Suprime Camera, the Magellan MegaCam and IMACS Cameras, and one with the Hubble Space Telescope—to find such KBOs for study. In this paper we overview the search criteria and strategies employed in our work and detail the analysis efforts to locate and track faint objects in the Galactic plane. We also present a summary of all of the KBOs that were discovered as part of our efforts and how spacecraft targetability was assessed, including a detailed description of our astrometric analysis, which included development of an extensive secondary calibration network. Overall, these efforts resulted in the discovery of 85 KBOs, including 11 that became objects for distant observation by New Horizons and (486958) Arrokoth, which became the first post-Pluto flyby destination.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142200979","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}
An important testable prediction of dynamical instability models for the early evolution of the solar system is that Jupiter Trojans share a source population with the Kuiper Belt. Concrete evidence of this prediction remains elusive, as Kuiper Belt objects (KBOs) and Jupiter Trojans appear to have different surface compositions. We address the long-standing question of Trojan origin by finding a dynamical subpopulation in the Kuiper Belt with Trojan-like colors. Combining existing photometric data with our own surveys on Keck I and Palomar P200, we find that the low-perihelion (q < 30 au, a > 30 au) component of the Kuiper Belt has colors that bifurcate similarly to the Jupiter Trojans, unlike Centaurs (a < 30 au), which have redder, Kuiper Belt-like colors. To connect the Jupiter Trojans to the Kuiper Belt, we test whether the distinct Trojan-like colors of low-perihelion KBOs result from surface processing or are sourced from a specific population in the Kuiper Belt. By simulating the evolution of the Canada–France Ecliptic Plane Survey synthetic population of KBOs for four billion years, we find that differences in heating timescales cannot result in a significant depletion of very red low-perihelion KBOs as compared to the Centaurs. We find that the neutrally colored scattered disk objects (e > 0.6 KBOs) contribute more to the low-perihelion KBO population than to Centaurs, resulting in their different colors.
太阳系早期演化的动力学不稳定性模型的一个重要的可检验预测是木星三剑星与柯伊伯带共享一个源群。由于柯伊伯带天体（KBOs）和木星特洛伊木星的表面成分似乎不同，这一预测的具体证据仍然难以捉摸。我们在柯伊伯带发现了一个具有类似特洛伊木马颜色的动态亚群，从而解决了特洛伊木马起源这一长期存在的问题。通过将现有的测光数据与我们自己在凯克 I 和帕洛玛 P200 上进行的巡天相结合，我们发现柯伊伯带的低近日点（q < 30 au, a > 30 au）部分具有与木星特洛伊木马类似的颜色分叉，而半人马（a < 30 au）则不同，它具有更红的类似柯伊伯带的颜色。为了将木星特洛伊木马与柯伊伯带联系起来，我们测试了低近日点KBOs独特的特洛伊木马般的颜色是表面加工的结果，还是来自柯伊伯带的一个特定种群。通过模拟加拿大-法国黄道平面巡天卫星合成KBOs群40亿年的演变过程，我们发现加热时间尺度的差异不会导致极红色低近日点KBOs比半人马显著减少。我们发现，中性色散射盘天体（e > 0.6 KBOs）对低近日点 KBO 群的贡献大于半人马天体，从而导致它们的颜色不同。
{"title":"The Trojan-like Colors of Low-perihelion Kuiper Belt Objects","authors":"Matthew Belyakov, Michael E. Brown, Alya Al-Kibbi","doi":"10.3847/psj/ad698a","DOIUrl":"https://doi.org/10.3847/psj/ad698a","url":null,"abstract":"An important testable prediction of dynamical instability models for the early evolution of the solar system is that Jupiter Trojans share a source population with the Kuiper Belt. Concrete evidence of this prediction remains elusive, as Kuiper Belt objects (KBOs) and Jupiter Trojans appear to have different surface compositions. We address the long-standing question of Trojan origin by finding a dynamical subpopulation in the Kuiper Belt with Trojan-like colors. Combining existing photometric data with our own surveys on Keck I and Palomar P200, we find that the low-perihelion (<italic toggle=\"yes\">q</italic> < 30 au, <italic toggle=\"yes\">a</italic> > 30 au) component of the Kuiper Belt has colors that bifurcate similarly to the Jupiter Trojans, unlike Centaurs (<italic toggle=\"yes\">a</italic> < 30 au), which have redder, Kuiper Belt-like colors. To connect the Jupiter Trojans to the Kuiper Belt, we test whether the distinct Trojan-like colors of low-perihelion KBOs result from surface processing or are sourced from a specific population in the Kuiper Belt. By simulating the evolution of the Canada–France Ecliptic Plane Survey synthetic population of KBOs for four billion years, we find that differences in heating timescales cannot result in a significant depletion of very red low-perihelion KBOs as compared to the Centaurs. We find that the neutrally colored scattered disk objects (<italic toggle=\"yes\">e</italic> > 0.6 KBOs) contribute more to the low-perihelion KBO population than to Centaurs, resulting in their different colors.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142200767","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}
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