Olivier Mousis, Antoine Schneeberger, Thibault Cavalié, Kathleen E. Mandt, Artyom Aguichine, Jonathan I. Lunine, Tom Benest Couzinou, Vincent Hue and Raphaël Moreno
This study, placed in the context of the preparation for the Uranus Orbiter Probe mission, aims to predict the bulk volatile compositions of Uranus and Neptune. Using a protoplanetary disk model, it examines the evolution of trace species through vapor and solid transport as dust and pebbles. Due to the high carbon abundance found in their envelopes, the two planets are postulated to have formed at the carbon monoxide ice line within the protosolar nebula. The time evolution of the abundances of the major volatile species at the location of the CO ice line is then calculated to derive the abundance ratios of the corresponding key elements, including the heavy noble gases, in the feeding zones of Uranus and Neptune. Supersolar metallicity in their envelopes likely results from accreting solids in these zones. Two types of solids are considered: pure condensates (Case 1) and a mixture of pure condensates and clathrates (Case 2). The model, calibrated to observed carbon enrichments, predicts deep compositions. In Case 1, argon is deeply depleted, while nitrogen, oxygen, krypton, phosphorus, sulfur, and xenon are significantly enriched relative to their protosolar abundances in the two planets. Case 2 predicts significant enrichments for all species, including argon, relative to their protosolar abundances. Consequently, Case 1 predicts near-zero Ar/Kr or Ar/Xe ratios, while Case 2 suggests that these ratios are 0.1 and 0.5–1 times their protosolar ratios, respectively. Both cases predict a bulk sulfur-to-nitrogen ratio consistent with atmospheric measurements.
{"title":"Insights on the Formation Conditions of Uranus and Neptune from Their Deep Elemental Compositions","authors":"Olivier Mousis, Antoine Schneeberger, Thibault Cavalié, Kathleen E. Mandt, Artyom Aguichine, Jonathan I. Lunine, Tom Benest Couzinou, Vincent Hue and Raphaël Moreno","doi":"10.3847/psj/ad58d8","DOIUrl":"https://doi.org/10.3847/psj/ad58d8","url":null,"abstract":"This study, placed in the context of the preparation for the Uranus Orbiter Probe mission, aims to predict the bulk volatile compositions of Uranus and Neptune. Using a protoplanetary disk model, it examines the evolution of trace species through vapor and solid transport as dust and pebbles. Due to the high carbon abundance found in their envelopes, the two planets are postulated to have formed at the carbon monoxide ice line within the protosolar nebula. The time evolution of the abundances of the major volatile species at the location of the CO ice line is then calculated to derive the abundance ratios of the corresponding key elements, including the heavy noble gases, in the feeding zones of Uranus and Neptune. Supersolar metallicity in their envelopes likely results from accreting solids in these zones. Two types of solids are considered: pure condensates (Case 1) and a mixture of pure condensates and clathrates (Case 2). The model, calibrated to observed carbon enrichments, predicts deep compositions. In Case 1, argon is deeply depleted, while nitrogen, oxygen, krypton, phosphorus, sulfur, and xenon are significantly enriched relative to their protosolar abundances in the two planets. Case 2 predicts significant enrichments for all species, including argon, relative to their protosolar abundances. Consequently, Case 1 predicts near-zero Ar/Kr or Ar/Xe ratios, while Case 2 suggests that these ratios are 0.1 and 0.5–1 times their protosolar ratios, respectively. Both cases predict a bulk sulfur-to-nitrogen ratio consistent with atmospheric measurements.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931766","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}
Samantha Gwizd, Kathryn M. Stack, Raymond Francis, Fred Calef, Brett B. Carr, Chris Langley, Jamie Graff, þorsteinn Hanning Kristinsson, Vilhjálmur Páll Thorarensen, Eiríkur Bernharðsson, Michael Phillips, Matthew Varnam, Nathan Hadland, Jahnavi Shah, Jeffrey Moersch, Udit Basu, Joana R. C. Voigt and Christopher W. Hamilton
The Rover–Aerial Vehicle Exploration Network project field-tested planetary mission operations within a Mars analog environment in Iceland using stand-alone rover and helicopter architectures. Mission planning, implementation, and results are reported for the rover mission and briefly summarized for the helicopter mission. The outcomes of both missions are subsequently compared. Field implementation occurred from 2022 July to August at the Holuhraun lava flow. The rover science operations team executed a 14 sol (Martian day) mission that achieved mission, science, and sampling goals, including the contextualization, acquisition, and planned caching of two eolian and two rock samples. The helicopter science operations team executed a plan of comparable length but emphasized different science goals given long-range flight capabilities and landing limitations. The resolution and targetability of the rover payload enabled more detailed analyses, whereas the helicopter was better able to map flow-scale morphologies. The rover’s exploration was limited by daily mobility duration limits and hazardous terrain, whereas the helicopter’s exploration was constrained by landing site hazards. Resource limitations resulted from lengthier rover drives and data-volume-intensive helicopter imaging surveys. Future missions using combined rover–helicopter architectures should account for each spacecraft’s resource needs and acknowledge system strengths in different geologic settings. Both missions served to establish operations strategies and mission outcomes to be applied to future combined rover and helicopter mission architectures, while the helicopter mission also evaluated strategies and outcomes for future stand-alone airborne missions. Findings in this work are relevant to future missions seeking to optimize strategies for planetary mission operations.
{"title":"Comparing Rover and Helicopter Planetary Mission Architectures in a Mars Analog Setting in Iceland","authors":"Samantha Gwizd, Kathryn M. Stack, Raymond Francis, Fred Calef, Brett B. Carr, Chris Langley, Jamie Graff, þorsteinn Hanning Kristinsson, Vilhjálmur Páll Thorarensen, Eiríkur Bernharðsson, Michael Phillips, Matthew Varnam, Nathan Hadland, Jahnavi Shah, Jeffrey Moersch, Udit Basu, Joana R. C. Voigt and Christopher W. Hamilton","doi":"10.3847/psj/ad55f4","DOIUrl":"https://doi.org/10.3847/psj/ad55f4","url":null,"abstract":"The Rover–Aerial Vehicle Exploration Network project field-tested planetary mission operations within a Mars analog environment in Iceland using stand-alone rover and helicopter architectures. Mission planning, implementation, and results are reported for the rover mission and briefly summarized for the helicopter mission. The outcomes of both missions are subsequently compared. Field implementation occurred from 2022 July to August at the Holuhraun lava flow. The rover science operations team executed a 14 sol (Martian day) mission that achieved mission, science, and sampling goals, including the contextualization, acquisition, and planned caching of two eolian and two rock samples. The helicopter science operations team executed a plan of comparable length but emphasized different science goals given long-range flight capabilities and landing limitations. The resolution and targetability of the rover payload enabled more detailed analyses, whereas the helicopter was better able to map flow-scale morphologies. The rover’s exploration was limited by daily mobility duration limits and hazardous terrain, whereas the helicopter’s exploration was constrained by landing site hazards. Resource limitations resulted from lengthier rover drives and data-volume-intensive helicopter imaging surveys. Future missions using combined rover–helicopter architectures should account for each spacecraft’s resource needs and acknowledge system strengths in different geologic settings. Both missions served to establish operations strategies and mission outcomes to be applied to future combined rover and helicopter mission architectures, while the helicopter mission also evaluated strategies and outcomes for future stand-alone airborne missions. Findings in this work are relevant to future missions seeking to optimize strategies for planetary mission operations.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931767","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}
Brant M. Jones, Juan Diego Carrillo-Sánchez, Diego Janches, Menelaos Sarantos and Thomas M. Orlando
The kinetics of water formation on the lunar surface from impact-driven melts (IM) of meteoroids and recombinative desorption (RD) of solar-wind-implanted regolith grains is assessed. The ratio of water generated from RD:IM is ultimately controlled by the diffusion constant of the implanted defects. Higher diffusion activation energies of hydroxyls (-OH) result in more trapping of the implanted defects and, consequently, higher water production from IM versus RD. At diffusion activation energies >1 eV, water production from RD is negligible and IM is the dominant channel. Our results suggest that RD can be associated with the observed latitude and diurnal dependence but RD and/or micrometeorite IM are not major contributors to the water ice observed within the permanently shadowed regions (PSRs). This suggests that volcanic and/or delivery via large impactors are the more likely major sources of water on the Moon. However, our model generally agrees with the observed latitudinal dependence of the inferred OH/H2O and the overall diurnal trend from orbital observations in the infrared. In addition, our results also suggest that micrometeorites are responsible for the high content of molecular water in the glass of regolith grains.
本研究评估了流星体撞击驱动熔体（IM）和太阳风植入碎屑的重组解吸（RD）在月球表面形成水的动力学。RD与IM产生的水比例最终受控于植入缺陷的扩散常数。羟基（-OH）的扩散活化能越高，植入缺陷的捕获量就越大，因此，IM 与 RD 的产水量也就越高。当扩散活化能大于 1 eV 时，RD 的产水量可以忽略不计，IM 是主要的产水通道。我们的结果表明，RD 与观测到的纬度和昼夜相关性有关，但 RD 和/或微陨石 IM 并不是在永久阴影区（PSRs）内观测到的水冰的主要成因。这表明，火山和/或通过大型撞击器输送的水更有可能是月球上水的主要来源。不过，我们的模型与观测到的推断出的 OH/H2O 的纬度依赖性以及红外轨道观测到的总体昼夜变化趋势基本吻合。此外，我们的结果还表明，微陨石是造成碎屑玻璃中分子水含量高的原因。
{"title":"Water Generation on the Moon from Solar Wind and Meteoroid Impacts","authors":"Brant M. Jones, Juan Diego Carrillo-Sánchez, Diego Janches, Menelaos Sarantos and Thomas M. Orlando","doi":"10.3847/psj/ad5542","DOIUrl":"https://doi.org/10.3847/psj/ad5542","url":null,"abstract":"The kinetics of water formation on the lunar surface from impact-driven melts (IM) of meteoroids and recombinative desorption (RD) of solar-wind-implanted regolith grains is assessed. The ratio of water generated from RD:IM is ultimately controlled by the diffusion constant of the implanted defects. Higher diffusion activation energies of hydroxyls (-OH) result in more trapping of the implanted defects and, consequently, higher water production from IM versus RD. At diffusion activation energies >1 eV, water production from RD is negligible and IM is the dominant channel. Our results suggest that RD can be associated with the observed latitude and diurnal dependence but RD and/or micrometeorite IM are not major contributors to the water ice observed within the permanently shadowed regions (PSRs). This suggests that volcanic and/or delivery via large impactors are the more likely major sources of water on the Moon. However, our model generally agrees with the observed latitudinal dependence of the inferred OH/H2O and the overall diurnal trend from orbital observations in the infrared. In addition, our results also suggest that micrometeorites are responsible for the high content of molecular water in the glass of regolith grains.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141882284","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}
Perianne E. Johnson, Leslie A. Young, David Nesvorný, Xi Zhang
We estimate the loss of nitrogen from Pluto over its lifetime, including the giant planet instability period, which we term the “Wild Years.” We analyze the orbital migration of 53 simulated Plutinos, which are Kuiper Belt Objects (KBOs) captured into 3:2 mean-motion resonance with Neptune during the instability. This orbital migration brought the Plutinos from 20 to 30 au to their present-day orbits near 40 au along a nonlinear path that includes orbits with semimajor axes from 10 to 100 au. We model the thermal history that results from this migration and estimate the volatile loss rates due to the ever-changing thermal environment. Due to the early Sun’s enhanced ultraviolet radiation, the photochemical destruction rate during the Wild Years was a factor of 100 higher than the present-day rate, but this only results in a loss of ∼10 m global equivalent layer (GEL). The enhanced Jeans escape rate varies wildly with time, and a net loss of ∼100 cm GEL is predicted. Additionally, we model the impact history during the migration and find that impacts are a net source, not loss, of N2, contributing ∼100 cm GEL. The 100 cm GEL is 0.1% of the amount of N2 in Sputnik Planitia. We therefore conclude that Pluto did not lose an excessive amount of volatiles during the Wild Years, and its primordial volatile inventory can be approximated as its present-day inventory. However, significant fractions of this small total loss of N2 occurred during the Wild Years, so estimates made using present-day rates will be underestimates.
{"title":"Nitrogen Loss from Pluto’s Birth to the Present Day via Atmospheric Escape, Photochemical Destruction, and Impact Erosion","authors":"Perianne E. Johnson, Leslie A. Young, David Nesvorný, Xi Zhang","doi":"10.3847/psj/ad5e80","DOIUrl":"https://doi.org/10.3847/psj/ad5e80","url":null,"abstract":"We estimate the loss of nitrogen from Pluto over its lifetime, including the giant planet instability period, which we term the “Wild Years.” We analyze the orbital migration of 53 simulated Plutinos, which are Kuiper Belt Objects (KBOs) captured into 3:2 mean-motion resonance with Neptune during the instability. This orbital migration brought the Plutinos from 20 to 30 au to their present-day orbits near 40 au along a nonlinear path that includes orbits with semimajor axes from 10 to 100 au. We model the thermal history that results from this migration and estimate the volatile loss rates due to the ever-changing thermal environment. Due to the early Sun’s enhanced ultraviolet radiation, the photochemical destruction rate during the Wild Years was a factor of 100 higher than the present-day rate, but this only results in a loss of ∼10 m global equivalent layer (GEL). The enhanced Jeans escape rate varies wildly with time, and a net loss of ∼100 cm GEL is predicted. Additionally, we model the impact history during the migration and find that impacts are a net source, not loss, of N<sub>2</sub>, contributing ∼100 cm GEL. The 100 cm GEL is 0.1% of the amount of N<sub>2</sub> in Sputnik Planitia. We therefore conclude that Pluto did not lose an excessive amount of volatiles during the Wild Years, and its primordial volatile inventory can be approximated as its present-day inventory. However, significant fractions of this small total loss of N<sub>2</sub> occurred during the Wild Years, so estimates made using present-day rates will be underestimates.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"75 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141871442","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}
G. J. Cooke, D. R. Marsh, C. Walsh and F. Sainsbury-Martinez
Ozone (O3) is important for the survival of life on Earth because it shields the surface from ionizing ultraviolet radiation. However, the existence of O3 in Earth’s atmosphere is not always beneficial. Resulting from anthropogenic activity, O3 exists as a biologically harmful pollutant at the surface when it forms in the presence of sunlight and other pollutants. As a strong oxidizer, O3 can be lethal to several different organisms; thus, when assessing the potential habitability of an exoplanet, a key part is determining whether toxic gases could be present at its surface. Using the Whole Atmosphere Community Climate Model version 6 (WACCM6; a three-dimensional chemistry-climate model), 12 atmospheric simulations of the terrestrial exoplanet TRAPPIST-1 e are performed with a variety of O2 concentrations and assuming two different stellar spectra proposed in the literature. Four atmospheric simulations of the exoplanet Proxima Centauri b are also included. Some scenarios for both exoplanets exhibit time-averaged surface O3 mixing ratios exceeding harmful levels of 40 ppbv, with 2120 ppbv the maximum concentration found in the cases simulated. These concentrations are toxic and can be fatal to most life on Earth. In other scenarios O3 remains under harmful limits over a significant fraction of the surface, despite there being present regions that may prove inhospitable. In the case in which O3 is detected in a terrestrial exoplanet’s atmosphere, determining the surface concentration is an important step when evaluating a planet’s habitability.
{"title":"Lethal Surface Ozone Concentrations Are Possible on Habitable Zone Exoplanets","authors":"G. J. Cooke, D. R. Marsh, C. Walsh and F. Sainsbury-Martinez","doi":"10.3847/psj/ad53c3","DOIUrl":"https://doi.org/10.3847/psj/ad53c3","url":null,"abstract":"Ozone (O3) is important for the survival of life on Earth because it shields the surface from ionizing ultraviolet radiation. However, the existence of O3 in Earth’s atmosphere is not always beneficial. Resulting from anthropogenic activity, O3 exists as a biologically harmful pollutant at the surface when it forms in the presence of sunlight and other pollutants. As a strong oxidizer, O3 can be lethal to several different organisms; thus, when assessing the potential habitability of an exoplanet, a key part is determining whether toxic gases could be present at its surface. Using the Whole Atmosphere Community Climate Model version 6 (WACCM6; a three-dimensional chemistry-climate model), 12 atmospheric simulations of the terrestrial exoplanet TRAPPIST-1 e are performed with a variety of O2 concentrations and assuming two different stellar spectra proposed in the literature. Four atmospheric simulations of the exoplanet Proxima Centauri b are also included. Some scenarios for both exoplanets exhibit time-averaged surface O3 mixing ratios exceeding harmful levels of 40 ppbv, with 2120 ppbv the maximum concentration found in the cases simulated. These concentrations are toxic and can be fatal to most life on Earth. In other scenarios O3 remains under harmful limits over a significant fraction of the surface, despite there being present regions that may prove inhospitable. In the case in which O3 is detected in a terrestrial exoplanet’s atmosphere, determining the surface concentration is an important step when evaluating a planet’s habitability.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141786297","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}
Kyle A. Pearson, Eldar Noe, Daniel Zhao, Alphan Altinok and Alexander M. Morgan
One of the main objectives of the Mars Exploration Program is to search for evidence of past or current life on the planet. To achieve this, Mars exploration has been focusing on regions that may have liquid or frozen water. A set of critical areas may have seen cycles of ice thawing in the relatively recent past in response to periodic changes in the obliquity of Mars. In this work, we use convolutional neural networks to detect surface regions containing “brain terrain,” a landform on Mars whose similarity in morphology and scale to sorted stone circles on Earth suggests that it may have formed as a consequence of freeze/thaw cycles. We use large images (∼100–1000 megapixels) from the Mars Reconnaissance Orbiter to search for these landforms at resolutions close to a few tens of centimeters per pixel (∼25–50 cm). Over 58,000 images (∼28 TB) were searched (∼5% of the Martian surface), and we found detections in 201 images. To expedite the processing, we leverage a classifier network (prior to segmentation) in the Fourier domain that can take advantage of JPEG compression by leveraging blocks of coefficients from a discrete cosine transform in lieu of decoding the entire image at the full spatial resolution. The hybrid pipeline approach maintains ∼93% accuracy while cutting down on ∼95% of the total processing time compared to running the segmentation network at the full resolution on every image.
{"title":"Mapping “Brain Terrain” Regions on Mars Using Deep Learning","authors":"Kyle A. Pearson, Eldar Noe, Daniel Zhao, Alphan Altinok and Alexander M. Morgan","doi":"10.3847/psj/ad5673","DOIUrl":"https://doi.org/10.3847/psj/ad5673","url":null,"abstract":"One of the main objectives of the Mars Exploration Program is to search for evidence of past or current life on the planet. To achieve this, Mars exploration has been focusing on regions that may have liquid or frozen water. A set of critical areas may have seen cycles of ice thawing in the relatively recent past in response to periodic changes in the obliquity of Mars. In this work, we use convolutional neural networks to detect surface regions containing “brain terrain,” a landform on Mars whose similarity in morphology and scale to sorted stone circles on Earth suggests that it may have formed as a consequence of freeze/thaw cycles. We use large images (∼100–1000 megapixels) from the Mars Reconnaissance Orbiter to search for these landforms at resolutions close to a few tens of centimeters per pixel (∼25–50 cm). Over 58,000 images (∼28 TB) were searched (∼5% of the Martian surface), and we found detections in 201 images. To expedite the processing, we leverage a classifier network (prior to segmentation) in the Fourier domain that can take advantage of JPEG compression by leveraging blocks of coefficients from a discrete cosine transform in lieu of decoding the entire image at the full spatial resolution. The hybrid pipeline approach maintains ∼93% accuracy while cutting down on ∼95% of the total processing time compared to running the segmentation network at the full resolution on every image.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141784132","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}
Matija Ćuk, Harrison Agrusa, Rachel H. Cueva, Fabio Ferrari, Masatoshi Hirabayashi, Seth A. Jacobson, Jay McMahon, Patrick Michel, Paul Sánchez, Daniel J. Scheeres, Stephen Schwartz, Kevin J. Walsh and Yun Zhang
The near-Earth binary asteroid Didymos was the target of the planetary defense demonstration mission DART in 2022 September. The smaller binary component, Dimorphos, was impacted by the spacecraft in order to measure momentum transfer in kinetic impacts into rubble piles. DART and associated Earth-based observation campaigns have provided a wealth of scientific data on the Didymos–Dimorphos binary. DART revealed the largely oblate and ellipsoidal shape of Dimorphos before the impact, while the postimpact observations suggest that Dimorphos now has a prolate shape. Here we add those data points to the known properties of small binary asteroids and propose new paradigms of the radiative binary Yarkovsky–O’Keefe–Radzievskii–Paddack (BYORP) effect as well as tidal dissipation in small binaries. We find that relatively spheroidal bodies like Dimorphos made of small debris may experience a weaker and more size-dependent BYORP effect than previously thought. This could explain the observed values of period drift in several well-characterized binaries. We also propose that energy dissipation in small binaries is dominated by relatively brief episodes of large-scale movement of (likely surface) materials, rather than long-term steady-state tidal dissipation. We propose that one such episode was triggered on Dimorphos by the DART impact. Depending on the longevity of this high-dissipation regime, it is possible that Dimorphos will be more dynamically relaxed in time for the Hera mission than it was in the weeks following the impact.
{"title":"BYORP and Dissipation in Binary Asteroids: Lessons from DART","authors":"Matija Ćuk, Harrison Agrusa, Rachel H. Cueva, Fabio Ferrari, Masatoshi Hirabayashi, Seth A. Jacobson, Jay McMahon, Patrick Michel, Paul Sánchez, Daniel J. Scheeres, Stephen Schwartz, Kevin J. Walsh and Yun Zhang","doi":"10.3847/psj/ad5d5e","DOIUrl":"https://doi.org/10.3847/psj/ad5d5e","url":null,"abstract":"The near-Earth binary asteroid Didymos was the target of the planetary defense demonstration mission DART in 2022 September. The smaller binary component, Dimorphos, was impacted by the spacecraft in order to measure momentum transfer in kinetic impacts into rubble piles. DART and associated Earth-based observation campaigns have provided a wealth of scientific data on the Didymos–Dimorphos binary. DART revealed the largely oblate and ellipsoidal shape of Dimorphos before the impact, while the postimpact observations suggest that Dimorphos now has a prolate shape. Here we add those data points to the known properties of small binary asteroids and propose new paradigms of the radiative binary Yarkovsky–O’Keefe–Radzievskii–Paddack (BYORP) effect as well as tidal dissipation in small binaries. We find that relatively spheroidal bodies like Dimorphos made of small debris may experience a weaker and more size-dependent BYORP effect than previously thought. This could explain the observed values of period drift in several well-characterized binaries. We also propose that energy dissipation in small binaries is dominated by relatively brief episodes of large-scale movement of (likely surface) materials, rather than long-term steady-state tidal dissipation. We propose that one such episode was triggered on Dimorphos by the DART impact. Depending on the longevity of this high-dissipation regime, it is possible that Dimorphos will be more dynamically relaxed in time for the Hera mission than it was in the weeks following the impact.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"65 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141753983","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}
Matthew M. Dobson, Megan E. Schwamb, Alan Fitzsimmons, Charles Schambeau, Aren Beck, Larry Denneau, Nicolas Erasmus, A. N. Heinze, Luke J. Shingles, Robert J. Siverd, Ken W. Smith, John L. Tonry, Henry Weiland, David. R. Young, Michael S. P. Kelley, Tim Lister, Pedro H. Bernardinelli, Marin Ferrais, Emmanuel Jehin, Grigori Fedorets, Susan D. Benecchi, Anne J. Verbiscer, Joseph Murtagh, René Duffard, Edward Gomez, Joey Chatelain and Sarah Greenstreet
Centaurs are small solar system objects on chaotic orbits in the giant planet region, forming an evolutionary continuum with the Kuiper Belt objects and Jupiter-family comets. Some Centaurs are known to exhibit cometary activity, though unlike comets, this activity tends not to correlate with heliocentric distance, and the mechanism behind it is currently poorly understood. We utilize serendipitous observations from the Asteroid Terrestrial-impact Last Alert System, Zwicky Transient Facility, Panoramic Survey Telescope and Rapid Response System, Dark Energy Survey, and Gaia in addition to targeted follow-up observations from the Las Cumbres Observatory, TRAnsiting Planets and PlanetesImals Small Telescope South (TRAPPIST-South), and Gemini North telescope to analyze an unexpected brightening exhibited by the known active Centaur (2060) Chiron in 2021. This is highly indicative of a cometary outburst. As of 2023 February, Chiron had still not returned to its prebrightening magnitude. We find Chiron's rotational lightcurve, phase curve effects, and possible high-albedo surface features to be unlikely causes of this observed brightening. We consider the most likely cause to be an epoch of either new or increased cometary activity, though we cannot rule out a possible contribution from Chiron's reported ring system, such as a collision of as-yet-unseen satellites shepherding the rings. We find no evidence for a coma in our Gemini or TRAPPIST-South observations, though this does not preclude the possibility that Chiron is exhibiting a coma that is too faint for observation or constrained to the immediate vicinity of the nucleus.
半人马是太阳系中的小天体，在巨行星区的轨道上运行混乱，与柯伊伯带天体和木星系彗星形成一个演化连续体。已知一些半人马座会表现出彗星活动，但与彗星不同的是，这种活动往往与日心距离无关，而且其背后的机制目前还不甚明了。我们利用来自小行星撞击地球最后警报系统、兹威基瞬变设施、全景巡天望远镜和快速反应系统、暗能量巡天和盖亚的偶然观测数据，以及来自拉斯坎布雷斯天文台、TRAnsiting Planets and PlanetesImals Small Telescope South（TRAPPIST-South）和双子座北望远镜的有针对性的跟踪观测数据，来分析已知的活跃半人马座（2060 年）赤龙星在 2021 年表现出的意外增亮。这高度显示了彗星爆发的迹象。截至 2023 年 2 月，巨卫一仍未恢复到变亮前的星等。我们发现，巨卫星的自转光曲线、相位曲线效应以及可能的高地基表面特征都不太可能是造成此次观测到的变亮的原因。我们认为最有可能的原因是彗星活动出现了新的或增加的时期，不过我们也不能排除据报道凯戎星的星环系统可能对其产生的影响，比如尚未发现的卫星碰撞星环。我们在双子座或TRAPPIST-South的观测中没有发现彗星彗星的证据，但这并不排除巨卫一出现彗星彗星的可能性，因为彗星彗星太微弱，无法观测，或者彗星彗星仅限于星核附近。
{"title":"The Discovery and Evolution of a Possible New Epoch of Cometary Activity by the Centaur (2060) Chiron","authors":"Matthew M. Dobson, Megan E. Schwamb, Alan Fitzsimmons, Charles Schambeau, Aren Beck, Larry Denneau, Nicolas Erasmus, A. N. Heinze, Luke J. Shingles, Robert J. Siverd, Ken W. Smith, John L. Tonry, Henry Weiland, David. R. Young, Michael S. P. Kelley, Tim Lister, Pedro H. Bernardinelli, Marin Ferrais, Emmanuel Jehin, Grigori Fedorets, Susan D. Benecchi, Anne J. Verbiscer, Joseph Murtagh, René Duffard, Edward Gomez, Joey Chatelain and Sarah Greenstreet","doi":"10.3847/psj/ad543c","DOIUrl":"https://doi.org/10.3847/psj/ad543c","url":null,"abstract":"Centaurs are small solar system objects on chaotic orbits in the giant planet region, forming an evolutionary continuum with the Kuiper Belt objects and Jupiter-family comets. Some Centaurs are known to exhibit cometary activity, though unlike comets, this activity tends not to correlate with heliocentric distance, and the mechanism behind it is currently poorly understood. We utilize serendipitous observations from the Asteroid Terrestrial-impact Last Alert System, Zwicky Transient Facility, Panoramic Survey Telescope and Rapid Response System, Dark Energy Survey, and Gaia in addition to targeted follow-up observations from the Las Cumbres Observatory, TRAnsiting Planets and PlanetesImals Small Telescope South (TRAPPIST-South), and Gemini North telescope to analyze an unexpected brightening exhibited by the known active Centaur (2060) Chiron in 2021. This is highly indicative of a cometary outburst. As of 2023 February, Chiron had still not returned to its prebrightening magnitude. We find Chiron's rotational lightcurve, phase curve effects, and possible high-albedo surface features to be unlikely causes of this observed brightening. We consider the most likely cause to be an epoch of either new or increased cometary activity, though we cannot rule out a possible contribution from Chiron's reported ring system, such as a collision of as-yet-unseen satellites shepherding the rings. We find no evidence for a coma in our Gemini or TRAPPIST-South observations, though this does not preclude the possibility that Chiron is exhibiting a coma that is too faint for observation or constrained to the immediate vicinity of the nucleus.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"63 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141740879","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}
K. G. Hanley, Q. McKown, E. M. Cangi, C. Sands, N. North, P. M. Miklavčič, M. S. Bramble, J. M. Bretzfelder, B. D. Byron, J. Caggiano, J. T. Haber, S. J. Laham, D. Morrison-Fogel, K. A. Napier, R. F. Phillips, S. Ray, M. Sandford, P. Sinha, T. Hudson, J. E. C. Scully and L. Lowes
A mission to Jupiter's moon Io, the most volcanically active body in the solar system, was suggested as a priority for the New Frontiers program in the 2013 Planetary Science Decadal Survey. We present a New Frontiers–class mission concept, Vulcan, that was designed as an educational exercise through the Jet Propulsion Laboratory’s 2022 Planetary Science Summer School. Vulcan would leverage an instrument suite consisting of wide- and narrow-angle cameras, a thermal infrared spectrometer, two fluxgate magnetometers, and ion and electron electrostatic analyzers to conduct the most thorough investigation of Io to date. Using 78 flybys over a 2 yr primary science mission, Vulcan would characterize the effects of tidal forces on the differentiation state, crustal structure, and volcanism of Io and investigate potential interactions between Io's volcanoes, surface features, and atmosphere. Although Vulcan was developed as an academic exercise, we show that a New Frontiers–class mission to Io could achieve transformative science in both geophysics and plasma physics, unifying typically disparate subfields of planetary science. A dedicated mission to Io, in combination with the Europa Clipper and Jupiter Icy Moons Explorer missions, would address fundamental questions raised by the 2023 Planetary Science Decadal Survey and could complete our understanding of the spectrum of planetary habitability. Lessons learned from Vulcan could be applied to a New Frontiers 5 Io mission concept in the near future.
{"title":"The Vulcan Mission to Io: Lessons Learned during the 2022 JPL Planetary Science Summer School","authors":"K. G. Hanley, Q. McKown, E. M. Cangi, C. Sands, N. North, P. M. Miklavčič, M. S. Bramble, J. M. Bretzfelder, B. D. Byron, J. Caggiano, J. T. Haber, S. J. Laham, D. Morrison-Fogel, K. A. Napier, R. F. Phillips, S. Ray, M. Sandford, P. Sinha, T. Hudson, J. E. C. Scully and L. Lowes","doi":"10.3847/psj/ad5841","DOIUrl":"https://doi.org/10.3847/psj/ad5841","url":null,"abstract":"A mission to Jupiter's moon Io, the most volcanically active body in the solar system, was suggested as a priority for the New Frontiers program in the 2013 Planetary Science Decadal Survey. We present a New Frontiers–class mission concept, Vulcan, that was designed as an educational exercise through the Jet Propulsion Laboratory’s 2022 Planetary Science Summer School. Vulcan would leverage an instrument suite consisting of wide- and narrow-angle cameras, a thermal infrared spectrometer, two fluxgate magnetometers, and ion and electron electrostatic analyzers to conduct the most thorough investigation of Io to date. Using 78 flybys over a 2 yr primary science mission, Vulcan would characterize the effects of tidal forces on the differentiation state, crustal structure, and volcanism of Io and investigate potential interactions between Io's volcanoes, surface features, and atmosphere. Although Vulcan was developed as an academic exercise, we show that a New Frontiers–class mission to Io could achieve transformative science in both geophysics and plasma physics, unifying typically disparate subfields of planetary science. A dedicated mission to Io, in combination with the Europa Clipper and Jupiter Icy Moons Explorer missions, would address fundamental questions raised by the 2023 Planetary Science Decadal Survey and could complete our understanding of the spectrum of planetary habitability. Lessons learned from Vulcan could be applied to a New Frontiers 5 Io mission concept in the near future.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141745899","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}
Elisabeth R. Adams, Brian Jackson, Amanda A. Sickafoose, Jeffrey P. Morgenthaler, Hannah Worters, Hailey Stubbers, Dallon Carlson, Sakhee Bhure, Stijn Dekeyser, Chelsea X. Huang and Nevin N. Weinberg
Ultrahot Jupiters (UHJs) are likely doomed by tidal forces to undergo orbital decay and eventual disruption by their stars, but the timescale over which this process unfolds is unknown. We present results from a long-term project to monitor UHJ transits. We recovered WASP-12 b’s orbital decay rate of ms yr−1, in agreement with prior work. Five other systems initially had promising nonlinear transit ephemerides. However, a closer examination of two—WASP-19 b and CoRoT-2 b, both with prior tentative detections—revealed several independent errors with the literature timing data; after correction, neither planet shows signs of orbital decay. Meanwhile, a potential decreasing period for TrES-1 b, ms yr−1, corresponds to a tidal quality factor and likely does not result from orbital decay if driven by dissipation within the host star. Nominal period increases in two systems, WASP-121 b and WASP-46 b, rest on a small handful of points. Only 1/43 planets (WASP-12 b) in our sample is experiencing detectable orbital decay. For nearly half (20/42), we can rule out as high as observed for WASP-12 b. Thus, while many UHJs could still be experiencing rapid decay that we cannot yet detect, a sizable subpopulation of UHJs are decaying at least an order of magnitude more slowly than WASP-12 b. Our reanalysis of Kepler-1658 b with no new data finds that it remains a promising orbital decay candidate. Finally, we recommend that the scientific community take steps to avoid spurious detections through better management of the multi-decade-spanning data sets needed to search for and study planetary orbital decay.
超热木星（UHJ）在潮汐力的作用下很可能注定要经历轨道衰变，并最终被恒星破坏，但这一过程展开的时间尺度尚不清楚。我们介绍了一个监测UHJ凌日的长期项目的结果。我们恢复了WASP-12 b的轨道衰减率，为毫秒/年-1，与之前的工作一致。其他五个系统最初的非线性凌日星历表也很有希望。然而，对两个系统--WASP-19 b和CoRoT-2 b（这两个系统之前都曾被初步探测到）的仔细研究发现，文献中的定时数据存在几个独立的错误；经过修正后，这两颗行星都没有轨道衰减的迹象。同时，TrES-1 b 的潜在衰减周期（ms yr-1）与潮汐质量因子相对应，如果是由宿主恒星内部的耗散驱动，则很可能不是轨道衰减造成的。WASP-121 b 和 WASP-46 b 这两个系统的标称周期增长只停留在少数几个点上。在我们的样本中，只有1/43的行星（WASP-12 b）正在经历可探测到的轨道衰变。因此，尽管许多 UHJ 仍在经历我们还无法探测到的快速衰变，但有相当一部分 UHJ 的衰变速度至少比 WASP-12 b 慢一个数量级。我们在没有新数据的情况下对开普勒-1658 b 进行的重新分析发现，它仍然是一个很有希望的轨道衰变候选者。最后，我们建议科学界采取措施，通过更好地管理搜索和研究行星轨道衰变所需的跨越数十年的数据集来避免虚假探测。
{"title":"Doomed Worlds. I. No New Evidence for Orbital Decay in a Long-term Survey of 43 Ultrahot Jupiters","authors":"Elisabeth R. Adams, Brian Jackson, Amanda A. Sickafoose, Jeffrey P. Morgenthaler, Hannah Worters, Hailey Stubbers, Dallon Carlson, Sakhee Bhure, Stijn Dekeyser, Chelsea X. Huang and Nevin N. Weinberg","doi":"10.3847/psj/ad3e80","DOIUrl":"https://doi.org/10.3847/psj/ad3e80","url":null,"abstract":"Ultrahot Jupiters (UHJs) are likely doomed by tidal forces to undergo orbital decay and eventual disruption by their stars, but the timescale over which this process unfolds is unknown. We present results from a long-term project to monitor UHJ transits. We recovered WASP-12 b’s orbital decay rate of ms yr−1, in agreement with prior work. Five other systems initially had promising nonlinear transit ephemerides. However, a closer examination of two—WASP-19 b and CoRoT-2 b, both with prior tentative detections—revealed several independent errors with the literature timing data; after correction, neither planet shows signs of orbital decay. Meanwhile, a potential decreasing period for TrES-1 b, ms yr−1, corresponds to a tidal quality factor and likely does not result from orbital decay if driven by dissipation within the host star. Nominal period increases in two systems, WASP-121 b and WASP-46 b, rest on a small handful of points. Only 1/43 planets (WASP-12 b) in our sample is experiencing detectable orbital decay. For nearly half (20/42), we can rule out as high as observed for WASP-12 b. Thus, while many UHJs could still be experiencing rapid decay that we cannot yet detect, a sizable subpopulation of UHJs are decaying at least an order of magnitude more slowly than WASP-12 b. Our reanalysis of Kepler-1658 b with no new data finds that it remains a promising orbital decay candidate. Finally, we recommend that the scientific community take steps to avoid spurious detections through better management of the multi-decade-spanning data sets needed to search for and study planetary orbital decay.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141740880","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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