Article
Astronomy & Astrophysics
T. T. Koskinen, D. F. Strobel, Z. Brown
Summary: The study presents an empirical model of H-2 densities and temperatures in the Saturn thermosphere based on Cassini/UVIS observations, which align well with other measurements. The model captures the main trend of increasing temperature with latitude in the thermosphere. The most significant source of uncertainty in the model is an apparent semi-annual variation in density and temperature.
Article
Astronomy & Astrophysics
Jordan K. Steckloff, David Goldstein, Laurence Trafton, Philip Varghese, Parvathy Prem
Summary: This study investigates the conditions for the formation and retention of exospheres on various celestial bodies in the Solar System. By constructing a free molecular model, the researchers explore the dynamics of volatile migration and the influence of different processes on exospheric evolution. The findings suggest that the CO2 exosphere of Callisto can be sustained by exposed CO2 ice distributed across its surface, while the two-tone appearance of Iapetus may be attributed to unresolved exposures of water ice. The study also reveals that the CO2 deposits on Uranus' moons are unlikely to be delivered via impacts, but could have originated from the planet's magnetosphere or an internal source. Furthermore, the researchers propose that exosphere-mediated volatile transport may contribute to the leading/trailing CO2 asymmetries observed on these moons. The study concludes by highlighting the importance of understanding exospheric dynamics for better understanding the evolution and composition of airless bodies in the Solar System.
Article
Astronomy & Astrophysics
James S. D. Blake, L. N. Fletcher, G. S. Orton, A. Antunano, M. T. Roman, Y. Kasaba, T. Fujiyoshi, H. Melin, D. Bardet, J. A. Sinclair, M. Es-Sayeh
Summary: Ground-based mid-infrared images of Saturn over a multi-decade period reveal seasonal and non-seasonal variability in thermal emission. 8-m class observatories can resolve thermal contrasts on various scales and confirm the consistency of Saturn's thermal structure from year to year. However, inter-annual variations are observed in the equatorial banding, suggesting the influence of tropospheric meteorology.
Review
Environmental Sciences
Imke de Pater, Edward M. Molter, Chris M. Moeckel
Summary: Radio observations of the giant planets in the solar system have been crucial in understanding their atmospheres, dynamics, and planet formation theories. Recent studies have revealed global circulation patterns, composition data supporting different planet formation scenarios, and constraints on models of outer proto-planetary disk and ice giant accretion. The importance of radio observations for planetary research will continue in the coming decades, particularly with the advancements in proposed and under-construction radio telescopes.
Article
Astronomy & Astrophysics
C. G. A. Smith
Summary: A three-dimensional linear model was developed to explain Saturn's planetary period oscillations, focusing on the interaction of Rossby waves and current systems. The model successfully describes observed current systems when opposite hemispheres have distinct PPO periods. However, the model falls short in explaining why the PPO current systems become 'locked' together with a specific phase relationship.
Article
Astronomy & Astrophysics
Jacob L. Gunnarson, Kunio M. Sayanagi, Georg Fischer, Trevor Barry, Anthony Wesley, Ulyana A. Dyudina, Shawn P. Ewald, Andrew P. Ingersoll
Summary: This article describes a cyclone in the atmosphere of Saturn that produced eight separate convective storms. By using images and instruments, the researchers were able to identify bright storm clouds within the cyclone and infer the duration and intensity of the storms through lightning signals. The cyclone survived six storms before being disrupted by the seventh and strongest storm, with an eighth storm occurring in the remnants of the disrupted cyclone.
Article
Astronomy & Astrophysics
John M. Barbara, Anthony D. Del Genio
Summary: An study on the wind profiles and eddy momentum fluxes in the clouds of Saturn's southern hemisphere and equatorial region reveals changes in wind speed strength at different altitude levels, as well as convergence and divergence patterns of eddy momentum fluxes around the eastward and westward jets. The study also notes the challenges of verifying the strength of equatorial jets near the equator, as well as the increase in eddy convergence from the troposphere to the lower stratosphere and the divergence of eddy flux from the middle to the upper troposphere and stratosphere.
Article
Astronomy & Astrophysics
J. M. Chadney, T. T. Koskinen, X. Hu, M. Galand, P. Lavvas, Y. C. Unruh, J. Serigano, S. M. Horst, R. Yelle
Summary: Researchers constructed neutral temperature and density profiles of H, H-2, He, and CH4 in Saturn's equatorial region using data from Cassini's instruments. They used an energy deposition model to calculate ion production rate profiles and rates of CH4 photo-dissociation, finding that high-resolution H-2 cross sections produce additional ionization peaks near 800 km altitude.
Review
Environmental Sciences
Csaba Palotai, Shawn Brueshaber, Ramanakumar Sankar, Kunio Sayanagi
Summary: The atmospheres of the outer planets in our Solar System exhibit a wide array of intriguing cloud features, varying in color and size. The distinct differences in cloud types observed suggest a complex interplay between the dynamics and chemistry at play in these atmospheres. The contrasting banded structures of Jupiter and Saturn compared to the sporadic clouds on the ice giants highlight the diverse dynamic, chemical, and thermal processes shaping these atmospheres. This review presents evidence of moist convective activity in the gas giant atmospheres of our Solar System through remote sensing data from both ground- and space-based observations. The processes driving moist convective activity, including dynamics and microphysics shaping the resulting clouds, are discussed, as well as the effects of moist convection on large-scale dynamics such as jet structures on these planets.
Article
Astronomy & Astrophysics
D. Lemasquerier, B. Favier, M. Le Bars
Summary: This study presents experimental results from a laboratory analog of zonal jets in deep gas giants. The researchers found that turbulent zonal jets can spontaneously emerge and reach equilibrium in the experiments, with up to 70% of the total kinetic energy of the flow. They also validated the zonostrophic theory in a fully three-dimensional framework. Additionally, they quantified the mixing of potential vorticity in the flow and showed that it can be estimated using the Thorpe scale.
Article
Astronomy & Astrophysics
Julianne Moses, Zarah L. Brown, Tommi T. Koskinen, Leigh N. Fletcher, Joseph Serigano, Sandrine Guerlet, Luke Moore, J. Hunter Waite, Lotfi Ben-Jaffel, Marina Galand, Joshua M. Chadney, Sarah M. Horst, James A. Sinclair, Veronique Vuitton, Ingo Muller-Wodarg
Summary: During the Grand Finale stage of the Cassini mission, researchers discovered the flow of organic-rich ring material into Saturn's equatorial upper atmosphere. Through photochemical models, they studied the impact of this material on the composition of Saturn's atmosphere. However, observations did not confirm the predicted chemical consequences, leading to the conclusion that the ring influx may have been a transient event triggered by a recent dynamical event or that the material entered the atmosphere in the form of small dust particles.
Article
Astronomy & Astrophysics
Nicholas A. Lombardo, Juan M. Lora
Summary: Titan's atmosphere shows variations in composition as it goes through different seasons. Winter stratosphere above 100 km has been found to have higher amounts of short-lived molecules. Seasonal changes in stratospheric dynamics on Titan also lead to a transient detached haze layer above 400 km. These seasonal variations affect the radiative heating rates in both shortwave and longwave regions. Based on simulations using the Titan Atmospheric Model (TAM), this study examines the impact of a new dataset derived from Cassini observations on aerosol opacity and trace gas abundance. The results show that including seasonally varying radiative species (SVRS) decreases the temperature of polar stratopause in autumn and winter by up to 10 K, and increases the seasonality in zonal winds.
Article
Astronomy & Astrophysics
Darrell F. Strobel
Summary: The paper aims to investigate whether the H-2 density measurements reported by Cassini were overestimated by a factor of 2.2, and the potential impact of this overestimation on the atmospheres of Titan and Saturn.
Article
Astronomy & Astrophysics
Shane R. Carberry Mogan, Orenthal J. Tucker, Robert E. Johnson, Audrey Vorburger, Andre Galli, Benoit Marchand, Angelo Tafuni, Sunil Kumar, Iskender Sahin, Katepalli R. Sreenivasan
Summary: A simulation tool using parallel processing was developed to study molecular kinetics in 2D atmospheres on Callisto, showing that the presence of H-2 molecules can cool local temperatures through collisions and that the difference in H-2 atmospheric escape rates between single-species and multi-species atmospheres is small.
Article
Environmental Sciences
Amy A. Simon, Michael H. Wong, Lawrence A. Sromovsky, Leigh N. Fletcher, Patrick M. Fry
Summary: Observations of the giant planets have been limited to infrequent robotic spacecraft missions, but the Hubble Space Telescope and ground-based telescopes with adaptive optics have provided high-resolution imaging and long-term monitoring. These observations have allowed for in-depth studies of the clouds, winds, and atmospheric structure, as well as comparisons between different planets and regions. Temporal variations in various aspects of the atmospheres have been measured, and future facilities will further enhance our understanding of atmospheric evolution on these planets.
Article
Astronomy & Astrophysics
Julianne Moses, Zarah L. Brown, Tommi T. Koskinen, Leigh N. Fletcher, Joseph Serigano, Sandrine Guerlet, Luke Moore, J. Hunter Waite, Lotfi Ben-Jaffel, Marina Galand, Joshua M. Chadney, Sarah M. Horst, James A. Sinclair, Veronique Vuitton, Ingo Muller-Wodarg
Summary: During the Grand Finale stage of the Cassini mission, researchers discovered the flow of organic-rich ring material into Saturn's equatorial upper atmosphere. Through photochemical models, they studied the impact of this material on the composition of Saturn's atmosphere. However, observations did not confirm the predicted chemical consequences, leading to the conclusion that the ring influx may have been a transient event triggered by a recent dynamical event or that the material entered the atmosphere in the form of small dust particles.
Article
Astronomy & Astrophysics
R. Lolachi, P. G. J. Irwin, N. A. Teanby
Summary: For the first time, we present retrievals of water vapour's vertical distribution from Mars Climate Sounder (MCS) aboard Mars Reconnaissance Orbiter (MRO), overcoming channel filter performance issues. The two-stage retrieval method was successfully applied to MCS observations, showing consistent results with other instruments. Important findings include the nightside vertical profiles of water vapour and its interaction with the aphelion cloud belt. The seasonal changes in the hygropause are reflected in variations of the cloud belt.
Article
Astronomy & Astrophysics
James S. D. Blake, L. N. Fletcher, G. S. Orton, A. Antunano, M. T. Roman, Y. Kasaba, T. Fujiyoshi, H. Melin, D. Bardet, J. A. Sinclair, M. Es-Sayeh
Summary: Ground-based mid-infrared images of Saturn over a multi-decade period reveal seasonal and non-seasonal variability in thermal emission. 8-m class observatories can resolve thermal contrasts on various scales and confirm the consistency of Saturn's thermal structure from year to year. However, inter-annual variations are observed in the equatorial banding, suggesting the influence of tropospheric meteorology.
Article
Astronomy & Astrophysics
Jingxuan Yang, Patrick G. J. Irwin, Joanna K. Barstow
Summary: This study proposes a novel method to analyze the spectroscopic phase curves of hot Jupiters, providing insights into their atmospheric properties. By applying this method, researchers have made important findings about WASP-43b, including the non-uniform temperature-pressure distribution and constraints on the abundance.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Review
Astronomy & Astrophysics
Leigh N. Fletcher, Thibault Cavalie, Davide Grassi, Ricardo Hueso, Luisa M. Lara, Yohai Kaspi, Eli Galanti, Thomas K. Greathouse, Philippa M. Molyneux, Marina Galand, Claire Vallat, Olivier Witasse, Rosario Lorente, Paul Hartogh, Francois Poulet, Yves Langevin, Pasquale Palumbo, G. Randall Gladstone, Kurt D. Retherford, Michele K. Dougherty, Jan-Erik Wahlund, Stas Barabash, Luciano Iess, Lorenzo Bruzzone, Hauke Hussmann, Leonid I. Gurvits, Ondrej Santolik, Ivana Kolmasova, Georg Fischer, Ingo Mueller-Wodarg, Giuseppe Piccioni, Thierry Fouchet, Jean-Claude Gerard, Agustin Sanchez-Lavega, Patrick G. J. Irwin, Denis Grodent, Francesca Altieri, Alessandro Mura, Pierre Drossart, Josh Kammer, Rohini Giles, Stephanie Cazaux, Geraint Jones, Maria Smirnova, Emmanuel Lellouch, Alexander S. Medvedev, Raphael Moreno, Ladislav Rezac, Athena Coustenis, Marc Costa
Summary: ESA's Jupiter Icy Moons Explorer (JUICE) will conduct a detailed investigation of the Jovian system in the 2030s, utilizing state-of-the-art instruments and a tailored orbital tour. The mission aims to gather information on the climate, meteorology, and chemistry of Jupiter's atmosphere and auroras, as well as studying phenomena on various timescales. The remote sensing payload includes spectroscopy, imaging, and sounding techniques, allowing for a comprehensive characterization of the planet's atmosphere and auroras.
SPACE SCIENCE REVIEWS
(2023)
Article
Geochemistry & Geophysics
Arjuna James, Patrick G. J. Irwin, Jack Dobinson, Michael H. Wong, Troy K. Tsubota, Amy A. Simon, Leigh N. Fletcher, Michael T. Roman, Nick A. Teanby, Daniel Toledo, Glenn S. Orton
Summary: Observations from the Hubble Space Telescope confirm the brightening of Uranus' north polar hood over time. The brightening is mainly attributed to changes in the aerosol scattering properties, particularly the thickening and increased reflectivity of the 1-2 bar haze layer.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Multidisciplinary Sciences
Samantha K. K. Trumbo, Michael E. E. Brown, Dominique Bockelee-Morvan, Imke de Pater, Thierry Fouchet, Michael H. H. Wong, Stephanie Cazaux, Leigh N. Fletcher, Katherine de Kleer, Emmanuel Lellouch, Alessandro Mura, Olivier Poch, Eric Quirico, Pablo Rodriguez-Ovalle, Mark R. R. Showalter, Matthew S. S. Tiscareno, Federico Tosi
Summary: Ganymede, the only satellite with an intrinsic magnetic field, experiences interactions with the Jovian magnetosphere, resulting in the accumulation of charged particles in its polar regions. Observations with JWST have revealed the presence of hydrogen peroxide, a product of radiolysis, at high latitudes, indicating the modification of polar caps by precipitation of Jovian charged particles along partially open field lines within Ganymede's magnetosphere. This discovery, along with the contrasting distribution of hydrogen peroxide on Europa, has important implications for understanding water-ice radiolysis in the solar system.
Article
Astronomy & Astrophysics
Patrick G. J. Irwin, Jack Dobinson, Arjuna James, Michael H. Wong, Leigh N. Fletcher, Michael T. Roman, Nicholas A. Teanby, Daniel Toledo, Glenn S. Orton, Santiago Perez-Hoyos, Agustin Sanchez-Lavega, Lawrence Sromovsky, Amy A. Simon, Raul Morales-Juberias, Imke de Pater, Statia L. Cook
Summary: We have analyzed spectroscopic observations of a dark spot on Neptune, revealing that the darkening is caused by a deep aerosol layer at short wavelengths (<700 nm). This layer is likely the H2S condensation layer. Additionally, a bright spot on the edge of the dark spot, with a brightening of the same 5 bar layer at longer wavelengths (>700 nm), is observed and may be connected with the circulation that generates and sustains the dark spots.
Article
Astronomy & Astrophysics
Brandon Park Coy, Conor A. Nixon, Naomi Rowe-Gurney, Richard Achterberg, Nicholas A. Lombardo, Leigh N. Fletcher, Patrick Irwin
Summary: This work presents the first infrared spectra of Titan obtained from the Spitzer Space Telescope. The data includes emissions of various molecules such as CH4, C2H2, C2H4, C2H6, C3H4, C3H6, C3H8, C4H2, HCN, HC3N, and CO2. Comparisons with the Cassini Composite Infrared Spectrometer (CIRS) reveal discrepancies in the observations, suggesting the need for further analysis.
PLANETARY SCIENCE JOURNAL
(2023)
Article
Astronomy & Astrophysics
Ingrid J. Daubar, Benjamin A. Fernando, Raphael F. Garcia, Peter M. Grindrod, Geraldine Zenhaeusern, Natalia Wojcicka, Nicholas A. Teanby, Simon C. Staehler, Liliya Posiolova, Anna C. Horleston, Gareth S. Collins, Constantinos Charalambous, John Clinton, Maria E. Banks, Marouchka Froment, Philippe Lognonne, Mark Panning, W. Bruce Banerdt
Summary: The NASA InSight mission has detected two seismic events on Mars and has identified their impact sources. These events have been associated with impact craters observed in orbital images, confirming the occurrence of impact activity on Mars. This discovery brings the total number of confirmed impact-related seismic events on Mars to eight.
PLANETARY SCIENCE JOURNAL
(2023)
Article
Geochemistry & Geophysics
P. G. J. Irwin, J. Dobinson, A. James, M. H. Wong, L. N. Fletcher, M. T. Roman, N. A. Teanby, D. Toledo, G. S. Orton, S. Perez-Hoyos, A. Sanchez-Lavega, A. Simon, R. Morales-Juberias, I. de Pater
Summary: Spectral observations of Neptune in 2019 reveal spatial variations in aerosol scattering properties and methane abundance in the planet's atmosphere. The darkening of certain features in the atmosphere is due to spectrally dependent darkening of particles in a deep aerosol layer, while bright zones at longer wavelengths are attributed to brightening of particles in the same aerosol layer. The properties of an upper methane/haze aerosol layer remain constant with latitude, and variations in an upper tropospheric haze layer account for changes in reflectivity at methane-absorbing wavelengths.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Astronomy & Astrophysics
N. A. Teanby, P. G. J. Irwin, M. Sylvestre, C. A. Nixon, M. A. Cordiner
Summary: New constraints on the externally sourced stratospheric water abundance of Uranus and Neptune are presented using observations from Herschel's Heterodyne Instrument for the Far-Infrared. The results show consistent water abundance for Neptune compared to previous studies, while for Uranus, the cold stratospheric temperatures and condensation level further limit the water vapor.
PLANETARY SCIENCE JOURNAL
(2022)
Article
Astronomy & Astrophysics
Maria Angeles Lopez-Cayuela, Maria-Paz Zorzano, Juan Luis Guerrero-Rascado, Carmen Cordoba-Jabonero
Summary: The atmospheric dust cycle on Mars plays a dominant role in the planetary radiative balance, atmospheric photochemistry escape, and redistribution of materials on the surface. A methodology is presented to accurately describe the annual dust redistribution cycle on Mars using orbital global and seasonal measurements of atmospheric dust opacity. The analysis shows that approximately 4 trillion kilograms of dust is transported globally in the atmosphere during a typical Mars year.
Article
Astronomy & Astrophysics
Audrey Vorburger, Shahab Fatemi, Shane R. Carberry Mogan, Andre Galli, Lucas Liuzzo, Andrew R. Poppe, Lorenz Roth, Peter Wurz
Summary: The study presents new model results for the composition of Ganymede's atmosphere, finding that sublimation remains the major source process for H2O, while radiolysis induced by auroral electrons dominates the source fluxes for O2 and H2.
Article
Astronomy & Astrophysics
Qi He, Zhi Cao, Yuqi Qian, Hejiu Hui, Ioannis Baziotis, Long Xiao, Zaicong Wang, Biji Luo, Yiheng Li, Zongjun Ying, Yang Li
Summary: The Chang'e-5 mission collected lunar soil containing magnesian troctolitic granulites, which provide valuable information on the composition of the lunar crust. Through analysis and modeling, it is suggested that these granulites may have originated from the Pythagoras crater and were transported to the landing site.
Article
Astronomy & Astrophysics
Jordan M. Bretzfelder, Kathryn M. Stack, Abigail A. Fraeman, Mackenzie Day, William E. Dietrich, Alexander B. Bryk
Summary: This study investigates the development of bedrock ridges on Mars and their implications for wind history, deposition, and erosion in Gale crater.
Article
Astronomy & Astrophysics
Lot Ram, Diptiranjan Rout, Rahul Rathi, Paul Withers, Sumanta Sarkhel
Summary: This study investigates the impacts of interplanetary coronal mass ejections (ICMEs) on the Martian ionosphere, specifically the behavior of the ionospheric peak density and height during ICME passages. The study used observations from the Radio Occultation Science Experiment (ROSE) aboard the MAVEN spacecraft and selected 8 ICMEs from existing catalogs. The results show that ICMEs lead to an elevation of the ionospheric peak height and a decrease in peak density, and propose that vertical pressure gradient and electron temperature enhancement are plausible causes for ionospheric variability.
Article
Astronomy & Astrophysics
Benoit Jabaud, Riccardo Artoni, Gabriel Tobie, Erwan Le Menn, Patrick Richard
Summary: The Cassini spacecraft discovered active jets of water vapour and ice grains at the South Pole of Enceladus, resulting in the deposit of freshly erupted materials on the moon's icy surface. Similar processes may be happening on Europa as well. Determining the mechanical properties of fresh icy powder-like materials is essential for future landing and sampling missions. The flowability and surface energy of ice powders decrease with increasing temperatures, which may have implications for stable landing and the flow of ice materials on Enceladus and Europa.
Article
Astronomy & Astrophysics
Lydie Bonal, Eric Quirico, Gilles Montagnac, Mutsumi Komatsu, Yoko Kebukawa, Hikaru Yabuta, Kana Amano, Jens Barosch, Laure Bejach, George D. Cody, Emmanuel Dartois, Alexandre Dazzi, Bradley De Gregorio, Ariane Deniset-Besseau, Jean Duprat, Cecile Engrand, Minako Hashiguchi, Kanami Kamide, David Kilcoyne, Zita Martins, Jeremie Mathurin, Smail Mostefaoui, Larry Nittler, Takuji Ohigashi, Taiga Okumura, Laurent Remusat, Scott Sandford, Miho Shigenaka, Rhonda Stroud, Hiroki Suga, Yoshio Takahashi, Yasuo Takeichi, Yusuke Tamenori, Maximilien Verdier-Paoletti, Shohei Yamashita, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Hisayoshi Yurimoto, Shogo Tachibana, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Satoru Nakazawa, Masahiro Nishimura, Tatsuaki Okada, Takanao Saiki, Kanako Sakamoto, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Tomohiro Usui, Sei-ichiro Watanabe, Toru Yada, Kasumi Yogata, Makota Yoshikawa
Summary: This paper focuses on characterizing the thermal history of asteroid Ryugu by studying the structure of polyaromatic carbonaceous matter in the returned samples. The study finds that there is no structural difference in the polyaromatic component between the two sampling sites on Ryugu, indicating that the thermal metamorphism related to radioactive decay was not significant. However, some structural variability is observed within the particle set.
Article
Astronomy & Astrophysics
M. Luginin, A. Fedorova, D. Belyaev, F. Montmessin, O. Korablev, J. -l. Bertaux
Summary: Spectroscopic solar occultation measurements by the SPICAV/SOIR instrument onboard the Venus Express orbiter provided new data on the upper haze aerosol properties, its distribution, and variations. A joint analysis of data from two spectrometers revealed a bimodal distribution in about 50% of observations previously believed to be unimodal, and characterized the size distribution 10 km higher in the atmosphere compared to previous analysis.
Article
Astronomy & Astrophysics
A. Mahieux, S. Viscardy, K. L. Jessup, F. P. Mills, L. Trompet, S. Robert, S. Aoki, A. Piccialli, A. C. Vandaele
Summary: We report on the mean upper limit number densities and volume concentrations of H2CO, O-3, NH3, HCN, N2O, NO2, NO, and HO2 at the Venus terminator above the cloud layer. Attempts to detect these species using a statistical algorithm and the method presented by Trompet et al. (2021) were unsuccessful, and upper limits of detection are provided.
Article
Astronomy & Astrophysics
P. M. Streeter, S. R. Lewis, M. R. Patel, J. A. Holmes, K. Rajendran
Summary: The northern polar vortex on Mars shows a high degree of interannual repeatability in its structure and evolution, except during large dust storms. The seasonal timing of these storms seems to be the key factor determining their impacts on the polar vortex.
Article
Astronomy & Astrophysics
Michael T. Mellon, Hanna G. Sizemore, Jennifer L. Heldmann, Christopher P. McKay, Carol R. Stoker
Summary: The search for life is a major focus of Mars exploration, with temperature and water activity being key factors for habitability. The most recent habitable conditions occurred about 510 kyrs ago and lasted for about 10s of kyrs each occurrence. All latitudes offer potential for life exploration, but middle-latitude sites have access to 100-kyr-old ice that experienced past habitable conditions, while high-latitude sites offer access to ancient ice over 1 Myrs old.
Article
Astronomy & Astrophysics
Anthony Ozerov, Jeffrey C. Smith, Jessie L. Dotson, Randolph S. Longenbaugh, Robert L. Morris
Summary: The Geostationary Lightning Mapper (GLM) instruments, with their large combined field of view, are useful for studying the population of atmospheric phenomena like bolides. However, there are biases when using GLM for non-lightning purposes, which need to be studied and accounted for before precise measurements of bolide flux can be obtained. A Bayesian Poisson regression model was developed to estimate instrumental biases and the latitudinal variation of bolide flux concurrently. The estimated bias corresponds to the known sensitivity of the GLM instruments, and the latitudinal flux variation estimates are consistent with a strong bias towards high-velocity bolides, as compared to existing theoretical models.
Article
Astronomy & Astrophysics
P. Beck, P. Y. Meslin, A. Fau, O. Forni, O. Gasnault, J. Lasue, A. Cousin, S. Schroeder, S. Maurice, W. Rapin, R. C. Wiens, A. M. Ollila, E. Dehouck, N. Mangold, B. Garcia, S. Schwartz, W. Goetz, N. Lanza
Summary: Analysis of data obtained by ChemCam on Mars reveals that the carbon signal is mainly related to ionization of the atmosphere, with variability potentially linked to the physical state of the atmosphere. Up to sol 3355, no carbonate was detected in the ChemCam dataset, suggesting that it is not a major constituent (>50%) in the analyzed targets and that carbon in soils is not enriched beyond the limit of detection. The dominant salts found in Gale are sulfate and chlorides, while the absence of carbonates, seen in Jezero, may be due to differences in protolith.
Article
Astronomy & Astrophysics
Eloy Pena-Asensio, Jaakko Visuri, Josep M. Trigo-Rodriguez, Hector Socas-Navarro, Maria Gritsevich, Markku Siljama, Albert Rimola
Summary: The observation of interstellar objects 1I/'Oumuamua and 2I/Borisov suggests the existence of a larger population of smaller projectiles that impact our planet with unbound orbits. A statistical evaluation of uncertainties in the CNEOS database and study of its hyperbolic fireballs reveals an anisotropic geocentric radiant distribution and low orbital inclinations, challenging the assumption of a randomly incoming interstellar population. These findings suggest that apparent interstellar meteors may, in fact, be the result of accelerated meteoroid impacts caused by close encounters with massive objects within or passing through our solar system.
Article
Astronomy & Astrophysics
Cecilia W. S. Leung, Leslie K. Tamppari, David M. Kass, German Martinez, Erik Fischer, Michael D. Smith
Summary: Using a combination of orbital and surface observations, this study investigates the vertical distribution of water vapor in the lower atmospheres of Mars. The findings suggest that the assumption of uniformly mixed water vapor in the boundary layer is not always consistent with observational constraints. The results provide important insights into the seasonal transport of water and the role of regolith-atmospheric exchange.