Oliver Lay, Joe Masiero, Tommy Grav, Amy Mainzer, Frank Masci and Edward Wright
NASA's Near-Earth Object Surveyor mission, scheduled for launch in 2027 September, is designed to detect and characterize at least two-thirds of the potentially hazardous asteroids with diameters larger than 140 m in a nominal 5 yr mission. We describe a model to estimate the survey performance using a faster approach than the time domain survey simulator described in Mainzer et al. (2023). This model is applied to explain how the completeness for 5 and 10 yr surveys varies with orbit type and asteroid size and to identify orbits with notably high or low likelihoods of detection. Size alone is an incomplete proxy for impact hazard, so for each asteroid orbit, we also calculate the associated hazard based on the impact velocity and the relative likelihood of impact. We then estimate how effective the mission will be at anticipating impacts as a function of impact energy, finding that a 5 yr mission will identify 87% of potential impacts larger than 100 Mt (Torino-9, "Regional Devastation"). For a 10 yr mission, this increases to 94%. We also show how the distribution of warning time varies with impact energy.
{"title":"Asteroid Impact Hazard Warning from the Near-Earth Object Surveyor Mission","authors":"Oliver Lay, Joe Masiero, Tommy Grav, Amy Mainzer, Frank Masci and Edward Wright","doi":"10.3847/psj/ad4d9e","DOIUrl":"https://doi.org/10.3847/psj/ad4d9e","url":null,"abstract":"NASA's Near-Earth Object Surveyor mission, scheduled for launch in 2027 September, is designed to detect and characterize at least two-thirds of the potentially hazardous asteroids with diameters larger than 140 m in a nominal 5 yr mission. We describe a model to estimate the survey performance using a faster approach than the time domain survey simulator described in Mainzer et al. (2023). This model is applied to explain how the completeness for 5 and 10 yr surveys varies with orbit type and asteroid size and to identify orbits with notably high or low likelihoods of detection. Size alone is an incomplete proxy for impact hazard, so for each asteroid orbit, we also calculate the associated hazard based on the impact velocity and the relative likelihood of impact. We then estimate how effective the mission will be at anticipating impacts as a function of impact energy, finding that a 5 yr mission will identify 87% of potential impacts larger than 100 Mt (Torino-9, \"Regional Devastation\"). For a 10 yr mission, this increases to 94%. We also show how the distribution of warning time varies with impact energy.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141504670","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}
Sanjoy M. Som, Serhat Sevgen, Adam A. Suttle, Jeff S. Bowman and Britney E. Schmidt
Salty aqueous solutions (brines) occur on Earth and may be prevalent elsewhere. Serpentinization represents a family of geochemical reactions where the hydration of olivine-rich rocks can release aqueous hydrogen, H2(aq), as a byproduct, and hydrogen is a known basal electron donor for terrestrial biology. While the effects of lithological differences on serpentinization products have been thoroughly investigated, effects focusing on compositional differences of the reacting fluid have received less attention. In this contribution, we investigate how the chemistry of seawater-derived brines affects the generation of biologically available hydrogen resulting from the serpentinization of harzburgite. We numerically investigate the serpentinization of ultramafic rocks at equilibrium with an array of brines at different water activities (a proxy for salt concentration in aqueous fluids and a determinant for habitability) derived from seawater evaporation. Because the existing supersaturation of aqueous calcium carbonate, a contributor to dissolved inorganic carbon (DIC) in natural seawater, cannot be captured in equilibrium calculations, we bookend our calculations by enabling and suppressing carbonate minerals when simulating serpentinization. We find that the extent of DIC supersaturation can provide an important control of hydrogen availability. Increased DIC becomes a major sink for hydrogen by producing formate and associated complexes when the reacting fluids are acidic enough to allow for CO2. Indeed, H2(aq) reduces CO2(aq) to formate, leading to a hydrogen deficit. These conclusions provide additional insights into the habitability of brine systems, given their potential for serpentinization across diverse planetary bodies such as on Mars and ocean worlds.
{"title":"Thermodynamic Predictions of Hydrogen Generation during the Serpentinization of Harzburgite with Seawater-derived Brines","authors":"Sanjoy M. Som, Serhat Sevgen, Adam A. Suttle, Jeff S. Bowman and Britney E. Schmidt","doi":"10.3847/psj/ad42a1","DOIUrl":"https://doi.org/10.3847/psj/ad42a1","url":null,"abstract":"Salty aqueous solutions (brines) occur on Earth and may be prevalent elsewhere. Serpentinization represents a family of geochemical reactions where the hydration of olivine-rich rocks can release aqueous hydrogen, H2(aq), as a byproduct, and hydrogen is a known basal electron donor for terrestrial biology. While the effects of lithological differences on serpentinization products have been thoroughly investigated, effects focusing on compositional differences of the reacting fluid have received less attention. In this contribution, we investigate how the chemistry of seawater-derived brines affects the generation of biologically available hydrogen resulting from the serpentinization of harzburgite. We numerically investigate the serpentinization of ultramafic rocks at equilibrium with an array of brines at different water activities (a proxy for salt concentration in aqueous fluids and a determinant for habitability) derived from seawater evaporation. Because the existing supersaturation of aqueous calcium carbonate, a contributor to dissolved inorganic carbon (DIC) in natural seawater, cannot be captured in equilibrium calculations, we bookend our calculations by enabling and suppressing carbonate minerals when simulating serpentinization. We find that the extent of DIC supersaturation can provide an important control of hydrogen availability. Increased DIC becomes a major sink for hydrogen by producing formate and associated complexes when the reacting fluids are acidic enough to allow for CO2. Indeed, H2(aq) reduces CO2(aq) to formate, leading to a hydrogen deficit. These conclusions provide additional insights into the habitability of brine systems, given their potential for serpentinization across diverse planetary bodies such as on Mars and ocean worlds.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"161 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141504668","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 Gilbert-Janizek, Victoria S. Meadows and Jacob Lustig-Yaeger
Future astrophysics missions will seek extraterrestrial life via transmission and direct-imaging observations. To assess habitability and biosignatures, we need robust retrieval tools to analyze observed spectra, and infer surface and atmospheric properties with their uncertainties. We use a novel retrieval tool to assess accuracy in characterizing near-surface habitability and biosignatures via simulated transmission and direct-imaging spectra, based on the Origins Space Telescope (Origins) and LUVOIR mission concepts. We assess our ability to discriminate between an Earth-like and a false-positive O3 TRAPPIST-1 e with transmission spectroscopy. In reflected light, we assess the robustness of retrieval results to unmodeled cloud extinction. We find that assessing habitability using transmission spectra may be challenging due to relative insensitivity to surface temperature and near-surface H2O abundances. Nonetheless, our order-of-magnitude H2O constraints can discriminate extremely desiccated worlds. Direct imaging is insensitive to surface temperature and subject to the radius/albedo degeneracy, but this method proves highly sensitive to surface water abundance, achieving retrieval precision within 0.1% even with partial clouds. Concerning biosignatures, Origins-like transmission observations (t = 40 hr) may detect the CO2/CH4 pair on M-dwarf planets and differentiate between biological and false-positive O3 using H2O and abundant CO. In contrast, direct-imaging observations with LUVOIR-A (t = 10 hr) are better suited to constraining O2 and O3, and may be sensitive to wavelength-dependent water cloud features, but will struggle to detect modern-Earth-like abundances of methane. For direct imaging, we weakly detect a stratospheric ozone bulge by fitting the near-UV wings of the Hartley band.
{"title":"Retrieved Atmospheres and Inferred Surface Properties for Terrestrial Exoplanets Using Transmission and Reflected-light Spectroscopy","authors":"Samantha Gilbert-Janizek, Victoria S. Meadows and Jacob Lustig-Yaeger","doi":"10.3847/psj/ad381e","DOIUrl":"https://doi.org/10.3847/psj/ad381e","url":null,"abstract":"Future astrophysics missions will seek extraterrestrial life via transmission and direct-imaging observations. To assess habitability and biosignatures, we need robust retrieval tools to analyze observed spectra, and infer surface and atmospheric properties with their uncertainties. We use a novel retrieval tool to assess accuracy in characterizing near-surface habitability and biosignatures via simulated transmission and direct-imaging spectra, based on the Origins Space Telescope (Origins) and LUVOIR mission concepts. We assess our ability to discriminate between an Earth-like and a false-positive O3 TRAPPIST-1 e with transmission spectroscopy. In reflected light, we assess the robustness of retrieval results to unmodeled cloud extinction. We find that assessing habitability using transmission spectra may be challenging due to relative insensitivity to surface temperature and near-surface H2O abundances. Nonetheless, our order-of-magnitude H2O constraints can discriminate extremely desiccated worlds. Direct imaging is insensitive to surface temperature and subject to the radius/albedo degeneracy, but this method proves highly sensitive to surface water abundance, achieving retrieval precision within 0.1% even with partial clouds. Concerning biosignatures, Origins-like transmission observations (t = 40 hr) may detect the CO2/CH4 pair on M-dwarf planets and differentiate between biological and false-positive O3 using H2O and abundant CO. In contrast, direct-imaging observations with LUVOIR-A (t = 10 hr) are better suited to constraining O2 and O3, and may be sensitive to wavelength-dependent water cloud features, but will struggle to detect modern-Earth-like abundances of methane. For direct imaging, we weakly detect a stratospheric ozone bulge by fitting the near-UV wings of the Hartley band.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"144 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141528957","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}
To better assess the role that electrons play in exosphere production on icy bodies, we measured the total and O2 sputtering yields from H2O ice for electrons with energies between 0.75 and 10 keV and temperatures between 15 and 124.5 K. We find that both total and O2 yields increase with decreasing energy over our studied range, that they increase rapidly at temperatures above 60 K, and that the relative amount of H2O in the sputtered flux decreases quickly with increasing energy. Combining our data with other electron data in the literature, we show that the accuracy of a widely used sputtering model can be improved significantly for electrons by adjusting some of the intrinsic parameter values. Applying our results to Europa, we estimate that the contribution of electrons to the production of the O2 exosphere is equal to the combined contribution of all ions. In contrast, sputtering of O2 from Ganymede and Callisto appears to be dominated by irradiating ions, though electrons still likely contribute a nonnegligible amount. While our estimates could be further refined by examining the importance of spatial variations in electron flux, we conclude that, at the very least, electrons seem to be important for exosphere production on icy surfaces and should be included in future modeling efforts.
{"title":"Energy and Temperature Dependencies for Electron-induced Sputtering from H2O Ice: Implications for the Icy Galilean Moons","authors":"Rebecca A. Carmack and Mark J. Loeffler","doi":"10.3847/psj/ad484d","DOIUrl":"https://doi.org/10.3847/psj/ad484d","url":null,"abstract":"To better assess the role that electrons play in exosphere production on icy bodies, we measured the total and O2 sputtering yields from H2O ice for electrons with energies between 0.75 and 10 keV and temperatures between 15 and 124.5 K. We find that both total and O2 yields increase with decreasing energy over our studied range, that they increase rapidly at temperatures above 60 K, and that the relative amount of H2O in the sputtered flux decreases quickly with increasing energy. Combining our data with other electron data in the literature, we show that the accuracy of a widely used sputtering model can be improved significantly for electrons by adjusting some of the intrinsic parameter values. Applying our results to Europa, we estimate that the contribution of electrons to the production of the O2 exosphere is equal to the combined contribution of all ions. In contrast, sputtering of O2 from Ganymede and Callisto appears to be dominated by irradiating ions, though electrons still likely contribute a nonnegligible amount. While our estimates could be further refined by examining the importance of spatial variations in electron flux, we conclude that, at the very least, electrons seem to be important for exosphere production on icy surfaces and should be included in future modeling efforts.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141504671","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}
Lukas Wueller, Wajiha Iqbal, Thomas Frueh, Carolyn H. van der Bogert and Harald Hiesinger
We provide the first detailed 1:100,000 scale geomorphologic map of the ∼100 km Amundsen crater region, which is of high scientific relevance for future exploration, e.g., NASA’s VIPER mission, the Artemis program, and the Chinese International Lunar Research Station. We investigated the complex geological history of the region before and after the formation of Amundsen crater on the rims of the South Pole–Aitken (SPA) and Amundsen–Ganswindt basins. We present a new Amundsen crater formation age of ∼4.04 Ga, which, in contrast to previously derived ages, is based on non-light-plains terrain. The estimated maximum excavation depth for Amundsen crater is ∼8 km, and elevated concentrations of FeO near the crater suggest that Amundsen may have redistributed SPA-derived materials. Plains materials of various kinds were observed both inside and outside Amundsen crater and are estimated to be up to 350 m thick and ∼3.8 Ga old. A less cratered, tens of meters thick mantling unit indicates a resurfacing event ∼3.7 Ga ago. We highlight five potential exploration sites that satisfy technical constraints (such as shallow slopes, solar illumination, and Earth visibility), provide materials that can be sampled, and are capable of addressing multiple science objectives. Due to its accessibility and traversability, combined with its geologic diversity, proximity of permanently shadowed regions for studying volatile processes, and ability to address multiple science objectives, we confirm and reinforce the Amundsen crater region as a high-priority landing and exploration site.
{"title":"Geologic History of the Amundsen Crater Region Near the Lunar South Pole: Basis for Future Exploration","authors":"Lukas Wueller, Wajiha Iqbal, Thomas Frueh, Carolyn H. van der Bogert and Harald Hiesinger","doi":"10.3847/psj/ad2c04","DOIUrl":"https://doi.org/10.3847/psj/ad2c04","url":null,"abstract":"We provide the first detailed 1:100,000 scale geomorphologic map of the ∼100 km Amundsen crater region, which is of high scientific relevance for future exploration, e.g., NASA’s VIPER mission, the Artemis program, and the Chinese International Lunar Research Station. We investigated the complex geological history of the region before and after the formation of Amundsen crater on the rims of the South Pole–Aitken (SPA) and Amundsen–Ganswindt basins. We present a new Amundsen crater formation age of ∼4.04 Ga, which, in contrast to previously derived ages, is based on non-light-plains terrain. The estimated maximum excavation depth for Amundsen crater is ∼8 km, and elevated concentrations of FeO near the crater suggest that Amundsen may have redistributed SPA-derived materials. Plains materials of various kinds were observed both inside and outside Amundsen crater and are estimated to be up to 350 m thick and ∼3.8 Ga old. A less cratered, tens of meters thick mantling unit indicates a resurfacing event ∼3.7 Ga ago. We highlight five potential exploration sites that satisfy technical constraints (such as shallow slopes, solar illumination, and Earth visibility), provide materials that can be sampled, and are capable of addressing multiple science objectives. Due to its accessibility and traversability, combined with its geologic diversity, proximity of permanently shadowed regions for studying volatile processes, and ability to address multiple science objectives, we confirm and reinforce the Amundsen crater region as a high-priority landing and exploration site.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141504672","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. E. Denny, M. M. Hedman, D. Bockelée-Morvan, G. Filacchione and F. Capaccioni
Water vapor produces a series of diagnostic emission lines in the near-infrared between 2.60 and 2.75 μm. The Visual and Infrared Mapping Spectrometer (VIMS) on board the Cassini spacecraft detected this emission signal from Enceladus’s plume, and so VIMS observations provide information about the variability of the plume’s water-vapor content. Using a data set of 249 spectral cubes with relatively high signal-to-noise ratios, we confirmed the strength of this water-vapor emission feature corresponds to a line-of-sight column density of order 1020 molecules m−2, which is consistent with previous measurements from Cassini’s Ultraviolet Imaging Spectrograph. Comparing observations made at different times indicates that the water-vapor flux is unlikely to vary systematically with Enceladus’s orbital phase, unlike the particle flux, which does vary with orbital phase. However, variations in the column density on longer and shorter timescales cannot be ruled out and merit further investigation.
{"title":"Constraining Time Variations in Enceladus’s Water-vapor Plume with Near-infrared Spectra from Cassini’s Visual and Infrared Mapping Spectrometer","authors":"K. E. Denny, M. M. Hedman, D. Bockelée-Morvan, G. Filacchione and F. Capaccioni","doi":"10.3847/psj/ad4c69","DOIUrl":"https://doi.org/10.3847/psj/ad4c69","url":null,"abstract":"Water vapor produces a series of diagnostic emission lines in the near-infrared between 2.60 and 2.75 μm. The Visual and Infrared Mapping Spectrometer (VIMS) on board the Cassini spacecraft detected this emission signal from Enceladus’s plume, and so VIMS observations provide information about the variability of the plume’s water-vapor content. Using a data set of 249 spectral cubes with relatively high signal-to-noise ratios, we confirmed the strength of this water-vapor emission feature corresponds to a line-of-sight column density of order 1020 molecules m−2, which is consistent with previous measurements from Cassini’s Ultraviolet Imaging Spectrograph. Comparing observations made at different times indicates that the water-vapor flux is unlikely to vary systematically with Enceladus’s orbital phase, unlike the particle flux, which does vary with orbital phase. However, variations in the column density on longer and shorter timescales cannot be ruled out and merit further investigation.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141504674","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}
Miki Nakajima, Jeremy Atkins, Jacob B. Simon and Alice C. Quillen
It is generally accepted that the Moon accreted from the disk formed by an impact between the proto-Earth and impactor, but its details are highly debated. Some models suggest that a Mars-sized impactor formed a silicate melt-rich (vapor-poor) disk around Earth, whereas other models suggest that a highly energetic impact produced a silicate vapor-rich disk. Such a vapor-rich disk, however, may not be suitable for the Moon formation, because moonlets, building blocks of the Moon, of 100 m–100 km in radius may experience strong gas drag and fall onto Earth on a short timescale, failing to grow further. This problem may be avoided if large moonlets (≫100 km) form very quickly by streaming instability, which is a process to concentrate particles enough to cause gravitational collapse and rapid formation of planetesimals or moonlets. Here, we investigate the effect of the streaming instability in the Moon-forming disk for the first time and find that this instability can quickly form ∼100 km-sized moonlets. However, these moonlets are not large enough to avoid strong drag, and they still fall onto Earth quickly. This suggests that the vapor-rich disks may not form the large Moon, and therefore the models that produce vapor-poor disks are supported. This result is applicable to general impact-induced moon-forming disks, supporting the previous suggestion that small planets (<1.6 R⊕) are good candidates to host large moons because their impact-induced disks would likely be vapor-poor. We find a limited role of streaming instability in satellite formation in an impact-induced disk, whereas it plays a key role during planet formation.
{"title":"The Limited Role of the Streaming Instability during Moon and Exomoon Formation","authors":"Miki Nakajima, Jeremy Atkins, Jacob B. Simon and Alice C. Quillen","doi":"10.3847/psj/ad4863","DOIUrl":"https://doi.org/10.3847/psj/ad4863","url":null,"abstract":"It is generally accepted that the Moon accreted from the disk formed by an impact between the proto-Earth and impactor, but its details are highly debated. Some models suggest that a Mars-sized impactor formed a silicate melt-rich (vapor-poor) disk around Earth, whereas other models suggest that a highly energetic impact produced a silicate vapor-rich disk. Such a vapor-rich disk, however, may not be suitable for the Moon formation, because moonlets, building blocks of the Moon, of 100 m–100 km in radius may experience strong gas drag and fall onto Earth on a short timescale, failing to grow further. This problem may be avoided if large moonlets (≫100 km) form very quickly by streaming instability, which is a process to concentrate particles enough to cause gravitational collapse and rapid formation of planetesimals or moonlets. Here, we investigate the effect of the streaming instability in the Moon-forming disk for the first time and find that this instability can quickly form ∼100 km-sized moonlets. However, these moonlets are not large enough to avoid strong drag, and they still fall onto Earth quickly. This suggests that the vapor-rich disks may not form the large Moon, and therefore the models that produce vapor-poor disks are supported. This result is applicable to general impact-induced moon-forming disks, supporting the previous suggestion that small planets (<1.6 R⊕) are good candidates to host large moons because their impact-induced disks would likely be vapor-poor. We find a limited role of streaming instability in satellite formation in an impact-induced disk, whereas it plays a key role during planet formation.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141504673","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}
Throughout history, the definition of “class” and the construction of astronomical classification systems has been a deep scientific and philosophical problem: scientific because facts such as physical composition ideally need to be known for proper classification but often are not, philosophical because astronomers need to understand the philosophical assumptions behind their attempts at classification, and because different philosophical ideas such as “natural kinds” often guide classification, even if unconsciously. The primary lesson of history is that the most useful classifications of celestial objects are optimally based on their physical nature. The second lesson is that because discovery is an extended process consisting of detection, interpretation, and understanding, initial classifications may be phenomenological, based on characteristics that may be useful in early “detection” stages of extended discovery. By contrast, final classifications of “the thing itself,” is achieved only after the “understanding” stage of discovery and must have a physical basis. A third lesson is that class status is best determined within a comprehensive classification system in order to determine taxon level, e.g., class, type, subtype. Such a system, encompassing all astronomical objects, illustrates the problems of class and classification, problems that may be applied to exoplanet discoveries.
{"title":"Discovery and Classification in Astronomy: Scientific and Philosophical Challenges and the Importance of a Comprehensive and Consistent Classification System","authors":"Steven J. Dick","doi":"10.3847/psj/ad4edd","DOIUrl":"https://doi.org/10.3847/psj/ad4edd","url":null,"abstract":"Throughout history, the definition of “class” and the construction of astronomical classification systems has been a deep scientific and philosophical problem: scientific because facts such as physical composition ideally need to be known for proper classification but often are not, philosophical because astronomers need to understand the philosophical assumptions behind their attempts at classification, and because different philosophical ideas such as “natural kinds” often guide classification, even if unconsciously. The primary lesson of history is that the most useful classifications of celestial objects are optimally based on their physical nature. The second lesson is that because discovery is an extended process consisting of detection, interpretation, and understanding, initial classifications may be phenomenological, based on characteristics that may be useful in early “detection” stages of extended discovery. By contrast, final classifications of “the thing itself,” is achieved only after the “understanding” stage of discovery and must have a physical basis. A third lesson is that class status is best determined within a comprehensive classification system in order to determine taxon level, e.g., class, type, subtype. Such a system, encompassing all astronomical objects, illustrates the problems of class and classification, problems that may be applied to exoplanet discoveries.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"150 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141504675","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}
Jacob Haqq-Misra, Eric T. Wolf, Thomas J. Fauchez and Ravi K. Kopparapu
This paper highlights methods from geostatistics that are relevant to the interpretation, intercomparison, and synthesis of atmospheric model data, with a specific application to exoplanet atmospheric modeling. Climate models are increasingly used to study theoretical and observational properties of exoplanets, which include a hierarchy of models ranging from fast and idealized models to those that are slower but more comprehensive. Exploring large parameter spaces with computationally expensive models can be accomplished with sparse sampling techniques, but analyzing such sparse samples can pose challenges for conventional interpolation functions. Ordinary kriging is a statistical method for describing the spatial distribution of a data set in terms of the variogram function, which can be used to interpolate sparse samples across any number of dimensions. Variograms themselves may also be useful diagnostic tools for describing the spatial distribution of model data in exoplanet atmospheric model intercomparison projects. Universal kriging is another method that can synthesize data calculated by models of different complexity, which can be used to combine sparse samples of data from slow models with larger samples of data from fast models. Ordinary and universal kriging can also provide a way to synthesize model predictions with sparse samples of exoplanet observations and may have other applications in exoplanet science.
{"title":"Interpolation and Synthesis of Sparse Samples in Exoplanet Atmospheric Modeling","authors":"Jacob Haqq-Misra, Eric T. Wolf, Thomas J. Fauchez and Ravi K. Kopparapu","doi":"10.3847/psj/ad50a7","DOIUrl":"https://doi.org/10.3847/psj/ad50a7","url":null,"abstract":"This paper highlights methods from geostatistics that are relevant to the interpretation, intercomparison, and synthesis of atmospheric model data, with a specific application to exoplanet atmospheric modeling. Climate models are increasingly used to study theoretical and observational properties of exoplanets, which include a hierarchy of models ranging from fast and idealized models to those that are slower but more comprehensive. Exploring large parameter spaces with computationally expensive models can be accomplished with sparse sampling techniques, but analyzing such sparse samples can pose challenges for conventional interpolation functions. Ordinary kriging is a statistical method for describing the spatial distribution of a data set in terms of the variogram function, which can be used to interpolate sparse samples across any number of dimensions. Variograms themselves may also be useful diagnostic tools for describing the spatial distribution of model data in exoplanet atmospheric model intercomparison projects. Universal kriging is another method that can synthesize data calculated by models of different complexity, which can be used to combine sparse samples of data from slow models with larger samples of data from fast models. Ordinary and universal kriging can also provide a way to synthesize model predictions with sparse samples of exoplanet observations and may have other applications in exoplanet science.","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"161 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141504676","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}
Megan T. Gialluca, Rory Barnes, Victoria S. Meadows, Rodolfo Garcia, Jessica Birky, Eric Agol
JWST observations of the seven-planet TRAPPIST-1 system will provide an excellent opportunity to test outcomes of stellar-driven evolution of terrestrial planetary atmospheres, including atmospheric escape, ocean loss, and abiotic oxygen production. While most previous studies use a single luminosity evolution for the host star, we incorporate observational uncertainties in stellar mass, luminosity evolution, system age, and planetary parameters to statistically explore the plausible range of planetary atmospheric escape outcomes. We present probabilistic distributions of total water loss and oxygen production as a function of initial water content, for planets with initially pure water atmospheres and no interior–atmosphere exchange. We find that the interior planets are desiccated for initial water contents below 50 Earth oceans. For TRAPPIST-1e, f, g, and h, we report maximum water-loss ranges of <inline-formula> <tex-math> <?CDATA ${8.0}_{-0.9}^{+1.3}$?> </tex-math> <mml:math overflow="scroll"><mml:msubsup><mml:mrow><mml:mn>8.0</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>0.9</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>1.3</mml:mn></mml:mrow></mml:msubsup></mml:math> <inline-graphic xlink:href="psjad4454ieqn1.gif" xlink:type="simple"></inline-graphic> </inline-formula>, <inline-formula> <tex-math> <?CDATA ${4.8}_{-0.4}^{+0.6}$?> </tex-math> <mml:math overflow="scroll"><mml:msubsup><mml:mrow><mml:mn>4.8</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>0.4</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>0.6</mml:mn></mml:mrow></mml:msubsup></mml:math> <inline-graphic xlink:href="psjad4454ieqn2.gif" xlink:type="simple"></inline-graphic> </inline-formula>, <inline-formula> <tex-math> <?CDATA ${3.4}_{-0.3}^{+0.3}$?> </tex-math> <mml:math overflow="scroll"><mml:msubsup><mml:mrow><mml:mn>3.4</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>0.3</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>0.3</mml:mn></mml:mrow></mml:msubsup></mml:math> <inline-graphic xlink:href="psjad4454ieqn3.gif" xlink:type="simple"></inline-graphic> </inline-formula>, and <inline-formula> <tex-math> <?CDATA ${0.8}_{-0.1}^{+0.2}$?> </tex-math> <mml:math overflow="scroll"><mml:msubsup><mml:mrow><mml:mn>0.8</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>0.1</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>0.2</mml:mn></mml:mrow></mml:msubsup></mml:math> <inline-graphic xlink:href="psjad4454ieqn4.gif" xlink:type="simple"></inline-graphic> </inline-formula> Earth oceans, respectively, with corresponding maximum oxygen retention of <inline-formula> <tex-math> <?CDATA ${1290}_{-75}^{+75}$?> </tex-math> <mml:math overflow="scroll"><mml:msubsup><mml:mrow><mml:mn>1290</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>75</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>75</mml:mn></mml:mrow></mml:msubsup></mml:math> <inline-graphic xlink:href="psjad4454ieqn5.gif" xlink:type="simple"></inline-graphic> </inline-formul
{"title":"The Implications of Thermal Hydrodynamic Atmospheric Escape on the TRAPPIST-1 Planets","authors":"Megan T. Gialluca, Rory Barnes, Victoria S. Meadows, Rodolfo Garcia, Jessica Birky, Eric Agol","doi":"10.3847/psj/ad4454","DOIUrl":"https://doi.org/10.3847/psj/ad4454","url":null,"abstract":"JWST observations of the seven-planet TRAPPIST-1 system will provide an excellent opportunity to test outcomes of stellar-driven evolution of terrestrial planetary atmospheres, including atmospheric escape, ocean loss, and abiotic oxygen production. While most previous studies use a single luminosity evolution for the host star, we incorporate observational uncertainties in stellar mass, luminosity evolution, system age, and planetary parameters to statistically explore the plausible range of planetary atmospheric escape outcomes. We present probabilistic distributions of total water loss and oxygen production as a function of initial water content, for planets with initially pure water atmospheres and no interior–atmosphere exchange. We find that the interior planets are desiccated for initial water contents below 50 Earth oceans. For TRAPPIST-1e, f, g, and h, we report maximum water-loss ranges of <inline-formula>\u0000<tex-math>\u0000<?CDATA ${8.0}_{-0.9}^{+1.3}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mrow><mml:mn>8.0</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>0.9</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>1.3</mml:mn></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"psjad4454ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>, <inline-formula>\u0000<tex-math>\u0000<?CDATA ${4.8}_{-0.4}^{+0.6}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mrow><mml:mn>4.8</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>0.4</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>0.6</mml:mn></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"psjad4454ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>, <inline-formula>\u0000<tex-math>\u0000<?CDATA ${3.4}_{-0.3}^{+0.3}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mrow><mml:mn>3.4</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>0.3</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>0.3</mml:mn></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"psjad4454ieqn3.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>, and <inline-formula>\u0000<tex-math>\u0000<?CDATA ${0.8}_{-0.1}^{+0.2}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mrow><mml:mn>0.8</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>0.1</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>0.2</mml:mn></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"psjad4454ieqn4.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> Earth oceans, respectively, with corresponding maximum oxygen retention of <inline-formula>\u0000<tex-math>\u0000<?CDATA ${1290}_{-75}^{+75}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mrow><mml:mn>1290</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>75</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>75</mml:mn></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"psjad4454ieqn5.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formul","PeriodicalId":34524,"journal":{"name":"The Planetary Science Journal","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141504677","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：