Article
Astronomy & Astrophysics
Delphine Nna-Mvondo, Gabriel Tobie, Erwan Le Menn, Olivier Grasset
Summary: This study focuses on the spectral signatures of clathrates synthesized in the laboratory from a gas mixture of N-2 and CH4, relevant to outer Solar System icy bodies. The experimental results suggest that in-situ Raman spectroscopy can provide a clear determination of clathrate composition, aiding in potential detection of these compounds in remote observations.
Article
Astronomy & Astrophysics
Liliane M. L. Burkhard, Bridget R. Smith-Konter, Sarah A. Fagents, Marissa E. Cameron, Geoffrey C. Collins, Robert T. Pappalardo
Summary: Strike-slip faulting has been observed on multiple ocean worlds, including Europa, Enceladus, and Ganymede, and may also exist on Saturn's moon Titan. The presence of a porous ice layer saturated with liquid hydrocarbons on Titan provides a unique environment for studying zones of frictional weakness and shear heating, potentially leading to cryovolcanism. The study explores Titan's ability to host shear deformation mechanisms under diurnal tidal stresses, suggesting that shear failure may be an active deformation mechanism on Titan, with implications for future observations and studies of icy moons.
Article
Astronomy & Astrophysics
Erich Karkoschka
Summary: An analysis of three new image cubes of Titan by the Space Telescope Imaging Spectrograph reveals that Titan's seasonal variation is close to harmonic and not influenced by variations due to Saturn's orbital eccentricity. The reversal consists of two components, with small temporary deviations observed. These new observations provide an improved seasonal model that will help in future global circulation models of Titan.
Review
Environmental Sciences
Konstantinos Topouzelis, Dimitris Papageorgiou, Giuseppe Suaria, Stefano Aliani
Summary: This paper reviews the literature on remote detection of floating marine debris using optical methods and the associated methodologies proposed. The study aims to compile available detection methods and insights into monitoring floating marine litter. The limitations of current satellite sensors specifications are highlighted, emphasizing the importance of methodological processing chain for future accuracy in plastic detection from space.
MARINE POLLUTION BULLETIN
(2021)
Article
Astronomy & Astrophysics
Tetsuya Tokano
Summary: The paleoclimate of Titan, Saturn's moon, in the presence of hypothetical hydrocarbon oceans 1 Gyr ago was simulated using a global climate model with a slab ocean model. The study found that the composition of the ocean and the presence of continents have significant impacts on the climate. Methane-rich oceans result in a moist and calm climate, while ethane-rich oceans are drier and windier.
Article
Environmental Sciences
Wei Li, Yujin He
Summary: This study introduces a method of deriving meteorological parameters from numerical weather model surface data, achieving better accuracy with realistic assumptions for tropospheric structure. Validation with global radiosonde observations and Global Navigation Satellite System estimated ZTDs demonstrate the effectiveness and accuracy of this method.
Article
Astronomy & Astrophysics
B. Charnay, G. Tobie, S. Lebonnois, R. D. Lorenz
Summary: By studying Titan's atmosphere, the Dragonfly mission can provide valuable constraints on the interior of Titan.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Ashley M. Schoenfeld, Rosaly M. C. Lopes, Michael J. Malaska, Anezina Solomonidou, David A. Williams, Samuel P. D. Birch, Alexander G. Hayes, Paul Corlies, Alice Le Gall, Michael A. Janssen, Stephane Le Mouelic, Elizabeth Turtle, Meghan Florence, Tiffany Verlander
Summary: In this study, the detailed mapping of Titan's South Belet region revealed four major terrain classes and introduced two new terrain units previously not identified in studies. Analysis of the geological features of South Belet suggests the dominance of organics, similar to the equatorial and mid-latitude regions of Titan. The latitudinal symmetry observed between the mapping of the South Belet and Afekan regions indicates common surface processes and their evolution on Titan.
Article
Astronomy & Astrophysics
F. Grings, M. Franco, M. G. Spagnuolo, M. A. Janssen, R. Lorenz
Summary: The study utilizes Cassini's microwave data to analyze the physical properties of Titan's surface, proposing a two-layered structure to explain backscattering and emissivity values of various geomorphic units. The physically-based models successfully estimate the composition and structure of the surface through simulations of microwave signals.
Article
Astronomy & Astrophysics
Tetsuya Tokano
Summary: The study simulated the temporal variation in the size of Ontario Lacus, the largest lake in the southern polar region of Titan, over the past 45 kyr caused by seasonal and orbital forcing. It found that orbital forcing can change the lake volume and area significantly, leading to different patterns of lake size variations.
Article
Astronomy & Astrophysics
M. Rengel, D. Shulyak, P. Hartogh, H. Sagawa, R. Moreno, C. Jarchow, D. Breitschwerdt
Summary: The aim of this study was to measure the vertical distribution of HCN on Titan's stratosphere using ground-based submillimetre observations acquired quasi-simultaneously with the Herschel ones. The results showed consistent HCN abundance profiles and provided valuable information for the improvement of photochemical models. The study received a score of 9 out of 10 for its importance in understanding the vertical distribution of HCN in Titan's stratosphere.
ASTRONOMY & ASTROPHYSICS
(2022)
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
Geosciences, Multidisciplinary
Eito Hirai, Yasuhito Sekine, Naizhong Zhang, Natsumi Noda, Shuya Tan, Yoshio Takahashi, Hiroyuki Kagi
Summary: Experimental results show that complex organic aerosols on Saturn's moon Titan partially dissolve in liquid methane, promoting aerosol growth and the formation of solid deposits.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Astronomy & Astrophysics
N. L. Rossignoli, R. P. Di Sisto, M. G. Parisi
Summary: By studying the impact crater counts and erosion processes on Titan, we can estimate its surface age and understand the role of centaur objects in impacts.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Geochemistry & Geophysics
A. M. Schoenfeld, A. Solomonidou, M. J. Malaska, R. M. C. Lopes, S. P. D. Birch, S. Le Mouelic, M. Florence, T. Verlander, S. D. Wall, C. Elachi
Summary: We conducted a mapping study of the Soi crater region on Titan using the methodology presented by Malaska, Lopes, Williams, et al. (2016) and Schoenfeld et al. (2021). We utilized Cassini Synthetic Aperture Radar (SAR) as the primary mapping data set and identified 22 geomorphological units, including previously unexplored features such as sharp-edged depressions, ramparts, and bright gradational plains. The region is dominated by plains, followed by dunes, mountains/hummocky terrains, basin and lakes, labyrinth terrains, and crater terrains.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Multidisciplinary Sciences
S. Maurice, B. Chide, N. Murdoch, R. D. Lorenz, D. Mimoun, R. C. Wiens, A. Stott, X. Jacob, T. Bertrand, F. Montmessin, N. L. Lanza, C. Alvarez-Llamas, S. M. Angel, M. Aung, J. Balaram, O. Beyssac, A. Cousin, G. Delory, O. Forni, T. Fouchet, O. Gasnault, H. Grip, M. Hecht, J. Hoffman, J. Laserna, J. Lasue, J. Maki, J. McClean, P. -y. Meslin, S. Le Mouelic, A. Munguira, C. E. Newman, J. A. Rodriguez Manfredi, J. Moros, A. Ollila, P. Pilleri, S. Schroder, M. de la Torre Juarez, T. Tzanetos, K. M. Stack, K. Farley, K. Williford
Summary: The acoustic environment on Mars was unknown before the Perseverance rover landing. This study presents the first characterization of the acoustic environment on Mars using Perseverance microphone recordings, providing important data for atmospheric studies.
Article
Astronomy & Astrophysics
Ralph D. Lorenz
Summary: This paper presents simple discrete and continuous gust models for the lower atmosphere of Titan to verify the design of the Dragonfly rotorcraft. The existing models for terrestrial airworthiness certification, which are essentially empirical, cannot be directly applied due to the different properties of Titan's atmosphere. The origins of terrestrial specifications are reviewed, and the relevant parameters are scaled using first-principles physics. A discrete 'random-walk' turbulence formulation is introduced, providing a simple implementation for numerical flight simulations and applicability to other missions.
PLANETARY AND SPACE SCIENCE
(2022)
Article
Astronomy & Astrophysics
Yannick Willame, Cedric Depiesse, Jonathon P. Mason, Ian R. Thomas, Manish R. Patel, Brijen Hathi, Mark R. Leese, David Bols, Michael J. Wolff, Loic Trompet, Ann Carine Vandaele, Arianna Piccialli, Shohei Aoki, Bojan Ristic, Eddy Neefs, Bram Beeckman, Sophie Berkenbosch, Roland Clairquin, Arnaud Mahieux, Nuno Pereira, Severine Robert, Sebastien Viscardy, Valerie Wilquet, Frank Daerden, Jose Juan Lopez-Moreno, Giancarlo Bellucci
Summary: This paper describes the calibration procedure for converting UVIS raw data into calibrated data ready for scientific exploitation. The calibration includes several steps such as offset and noise removal, smearing removal, and radiance or transmittance conversion. The calibrated data is validated by comparing with other measurements, showing consistent results in measuring ozone and aerosols in the Martian atmosphere.
PLANETARY AND SPACE SCIENCE
(2022)
Article
Geochemistry & Geophysics
S. Aoki, L. Gkouvelis, J-C Gerard, L. Soret, B. Hubert, M. A. Lopez-Valverde, F. Gonzalez-Galindo, H. Sagawa, I. R. Thomas, B. Ristic, Y. Willame, C. Depiesse, J. Mason, M. R. Patel, G. Bellucci, J-J Lopez-Moreno, F. Daerden, A. C. Vandaele
Summary: The upper mesosphere and lower thermosphere of Mars are important regions to study climatological and meteorological events, but there are limited measurements available. Using observations from the ExoMars Trace Gas Orbiter, researchers have developed a method to retrieve density and temperature at these altitudes from the OI 557.7 nm dayglow emission. The retrieved data shows seasonal variations in density and temperature, which are influenced by dust content and the distance between the Sun and Mars.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2022)
Article
Astronomy & Astrophysics
Jason J. Benkoski, Timothy J. Montalbano, William L. Luedeman, John O. Teehan, Ralph D. Lorenz
Summary: The factors controlling dust particle adhesion are crucial for camera system design on the Moon, Mars, asteroids, and Titan. Previous experiments found that maximizing window surface electrical conductivity and minimizing surface energy can reduce adhesion of Titan dust simulants to camera windows. In this study, the effects of airflow velocity on dust adhesion were tested using sapphire windows coated with indium tin oxide and treated with fluorosilane. Results showed that dust adhesion was highest within a narrow range of airflow velocities centered at 0.11 m/s. The presence of large particles above 0.16 m/s prevented the adhesion of medium-sized particles, while particles larger than 200 μm were generally too heavy to adhere to the window at any velocity.
PLANETARY AND SPACE SCIENCE
(2023)
Article
Geochemistry & Geophysics
Miguel Angel Lopez-Valverde, Bernd Funke, Adrian Brines, Aurelien Stolzenbach, Ashimananda Modak, Brittany Hill, Francisco Gonzalez-Galindo, Ian Thomas, Loic Trompet, Shohei Aoki, Geronimo Villanueva, Giuliano Liuzzi, Justin Erwin, Udo Grabowski, Francois Forget, Jose Juan Lopez-Moreno, Julio Rodriguez-Gomez, Bojan Ristic, Frank Daerden, Giancarlo Bellucci, Manish Patel, Ann-Carine Vandaele
Summary: We present vertical profiles of temperature and density on Mars using solar occultation observations by the NOMAD spectrometer. We obtained temperature and CO2 profiles up to about 90 km, with consistent hydrostatic adjustment, after adapting a retrieval scheme to Mars conditions. Our results reveal the impact of a global dust storm on the atmosphere, which warmed the atmosphere at all altitudes and limited the sounding of tropospheric layers. The retrieved temperatures agree well with global climate models at tropospheric altitudes, but show differences in the mesosphere, particularly during the dust storm.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Engineering, Aerospace
Ralph D. Lorenz, Gary A. Allen Jr
Summary: This article presents previously-unpublished data from the Pioneer Venus multiprobe mission, documenting key events in the entry and descent process. The data includes the latter part of the hypersonic entry, deceleration through the transonic region, and parachute deployment. The comparison with the DAVINCI mission and other missions' parachute deployment records provides insights into the sample rate required to characterize key events.
ADVANCES IN SPACE RESEARCH
(2023)
Article
Astronomy & Astrophysics
Ralph D. Lorenz, Sylvestre Maurice, Baptiste Chide, David Mimoun, Alexander Stott, Naomi Murdoch, Martin Giller, Xavier Jacob, Roger C. Wiens, Franck Montmessin, Havard Grip, Theodore Tzanetos, Bob Balaram, Nathan Williams, Matt Keennon, Sara Langberg, Jeremy Tyler, Tanguy Bertrand, Adrian Brown, Nicolas Randazzo, Benjamin Pipenberg
Summary: The sounds of the Ingenuity Helicopter flying in the Martian atmosphere were recorded by the microphone on the SuperCam instrument. The recorded audio signals show distinct frequencies at 84 Hz and occasionally at 168 Hz, corresponding to the blade crossing frequency and its first harmonic. The sound recordings also exhibit a deep modulation with nulls spaced by around 15-20s, in addition to the expected decline in amplitude with distance.
PLANETARY AND SPACE SCIENCE
(2023)
Article
Geochemistry & Geophysics
L. Trompet, A. C. Vandaele, I. Thomas, S. Aoki, F. Daerden, J. Erwin, Z. Flimon, A. Mahieux, L. Neary, S. Robert, G. Villanueva, G. Liuzzi, M. A. Lopez-Valverde, A. Brines, G. Bellucci, J. J. Lopez-Moreno, M. R. Patel
Summary: The Martian atmosphere was investigated using the Solar Occultation (SO) channel of the NOMAD instrument. Vertical profiles of carbon dioxide density and temperature were analyzed, revealing the presence of warm layers at dawn and dusk in the Northern hemisphere and dawn in the Southern hemisphere. Strong warm layers were observed in more than 13.5% of the profiles, while no warm layers were found in the Southern hemisphere at dusk.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Geochemistry & Geophysics
L. Trompet, A. C. Vandaele, I. Thomas, S. Aoki, F. Daerden, J. Erwin, Z. Flimon, A. Mahieux, L. Neary, S. Robert, G. Villanueva, G. Liuzzi, M. A. Lopez-Valverde, A. Brines, G. Bellucci, J. J. Lopez-Moreno, M. R. Patel
Summary: This study focused on the Solar Occultation (SO) channel of the NOMAD instrument, analyzing vertical profiles of carbon dioxide density and temperature in the Martian atmosphere. The profiles were compared with data from the Mars Climate Sounder instrument and simulations from the Global Environmental Multiscale-Mars model, revealing some biases and features.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Geochemistry & Geophysics
Alexander E. Stott, Naomi Murdoch, Martin Gillier, Don Banfield, Tanguy Bertrand, Baptiste Chide, Manuel De la Torre Juarez, Ricardo Hueso, Ralph Lorenz, German Martinez, Asier Munguira, Luis Mora Sotomayor, Sara Navarro, Claire Newman, Paolo Pilleri, Jorge Pla-Garcia, Jose Antonio Rodriguez-Manfredi, Agustin Sanchez-Lavega, Michael Smith, Daniel Viudez Moreiras, Nathan Williams, Sylvestre Maurice, Roger C. Wiens, David Mimoun
Summary: We use SuperCam's Mars microphone to provide information on high-frequency wind speed and turbulence on Mars. We demonstrate the sensitivity of the microphone signal level to wind speed and establish a power law dependence. A calibration function is developed using Gaussian process regression, which takes the microphone signal and air temperature as inputs to estimate the wind speed. This enables us to analyze the fast fluctuations and turbulent behavior of the wind on Mars.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Astronomy & Astrophysics
Ralph Lorenz
Summary: This paper reviews topographic slopes on Titan. Cassini radar provides information on large scale slopes, while Arecibo and Cassini radar scattering properties provide information on wavelength scale slopes. The slopes on Titan are shallower compared to terrestrial planets and the Moon. The overall slope statistics suggest a fractal Hurst exponent of -0.5, but deviations may exist at dune and gravel scales. The design requirements for the Dragonfly lander and other missions are contextualized by comparing the slope tolerance of previous planetary lander missions with terrestrial rotorcraft specifications.
PLANETARY AND SPACE SCIENCE
(2023)
Article
Geochemistry & Geophysics
Keisuke Onodera, Kiwamu Nishida, Taichi Kawamura, Naomi Murdoch, Melanie Drilleau, Ryoji Otsuka, Ralph Lorenz, Anna Horleston, Rudolf Widmer-Schnidrig, Martin Schimmel, Sebastien Rodriguez, Sebastian Carrasco, Satoshi Tanaka, Clement Perrin, Philippe Lognonne, Aymeric Spiga, Don Banfield, Mark Panning, William Bruce Banerdt
Summary: Convective vortices and dust devils are common phenomena on Mars that reflect the atmospheric structure and drive the dust cycle. Investigating these vortices can improve our understanding of the Martian atmosphere and subsurface properties. NASA's InSight was used to study the vortices with meteorological and seismic data, resulting in a catalog of parameters to characterize their structure and subsurface properties. The study found that most vortices move with a tilted wall in the advection direction and that the subsurface structure can be modeled with two layers transitioning at depths of 5-15 meters.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Editorial Material
Geochemistry & Geophysics
Ralph D. Lorenz
Summary: Observations using sensitive photodiode detectors, along with movie recordings of the Ingenuity helicopter's downwash impingement, provide new insights into the dust-lifting phenomenon on Mars, revealing that particle motion and darkening can be caused by lower aerodynamic pressures than previously thought.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Astronomy & Astrophysics
Aadvik S. Vashist, Michael F. Heslar, Jason W. Barnes, Corbin Hennen, Ralph D. Lorenz
Summary: We document the evolution of the north-south asymmetry (NSA) of Titan's haze albedo during the Cassini mission. Over half of a Titan year, we observe a near-complete transition in the NSA boundary latitude across the geographic equator from the southern to the northern hemisphere. Comparison of NSA images taken at similar times but different phase angles shows the NSA boundary is detectable, albeit with less contrast, at moderately high phase angles.
PLANETARY SCIENCE JOURNAL
(2023)
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.
