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
Lauren R. Schurmeier, Andrew J. Dombard, Michael J. Malaska, Sarah A. Fagents, Jani Radebaugh, Daniel E. Lalich
Summary: Titan's labyrinth terrains are elevated, organic-rich landforms that hold clues about Titan's history and crust composition. One subtype, the radially networked labyrinth terrains, are dome-shaped features with radial drainage patterns, likely formed by cryomagmatic laccoliths. The intrusions would flex the lithosphere and sedimentary layers, resulting in dome-shaped, highly dissected terrain. The thickness of the methane clathrate crust is crucial for the formation of these features.
Article
Astronomy & Astrophysics
Kristen M. Luchsinger, Nancy J. Chanover, Paul D. Strycker
Summary: The LCROSS mission observed water ice in the Cabeus crater and obtained constraints on the mass and concentration of this ice through ground-based observations. The study suggests that a mixture of ice with increasing concentration and other materials could produce the impact cloud model consistent with ground-based observations.
Article
Astronomy & Astrophysics
H. M. Brown, A. K. Boyd, B. W. Denevi, M. R. Henriksen, M. R. Manheim, M. S. Robinson, E. J. Speyerer, R. Wagner
Summary: The lunar polar regions contain permanently shadowed regions that can cold-trap volatile materials in the form of ice, which are important resources for exploration. This study compiles observations to estimate the locations and mass of water ice deposits in PSRs.
Article
Astronomy & Astrophysics
Reggie L. Hudson
Summary: This study compares the infrared spectroscopic results on benzene ices from two recent papers and discusses the qualitative and quantitative differences between them. It identifies errors in one paper that, once corrected, could align the results with the other paper. A solution is provided for an unexplained disagreement with previous literature. The study concludes that the most accurate and extensive set of IR absorption coefficients, band strengths, and optical constants for amorphous and crystalline benzene is presented in the recent publications by the authors. Suggestions are made for future work to address this issue.
Article
Astronomy & Astrophysics
Yukiko Y. Yarnall, Reggie L. Hudson
Summary: This paper presents the results of density measurements on twenty-nine crystalline ices applicable to the outer Solar System and the interstellar medium. The study reveals a strong positive correlation between densities obtained from micrometer-size crystalline ice samples prepared by vapor-phase deposition and the larger crystals used in diffraction work.
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
Geochemistry & Geophysics
J. Mouzay, I. Couturier-Tamburelli, N. Pietri, T. Chiavassa
Summary: Laboratory experiments were conducted to study the photochemical evolution induced by long-UV irradiation of benzene ices in Titan's atmosphere. The formation of volatile photo-products and residue dominated by nu CH IR features from UV photolysis of benzene ices were observed, providing insights into the composition of Titan's stratospheric haze layer. Additionally, the characterization of benzene-containing aerosol analogs induced by long-UV will contribute to Titan's surface organics layer and future Dragonfly space mission.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2021)
Article
Astronomy & Astrophysics
J. Mouzay, K. Henry, I Couturier-Tamburelli, G. Danger, N. Pietri, T. Chiavassa
Summary: A massive noxious stratospheric cloud has been detected on Titan's south pole since 2015, with an experimental simulation showing the presence of nitriles formed through photo-processing. These results are crucial for the upcoming Dragonfly mission on Titan, shedding light on the potential organic compounds present in the stratospheric cloud.
Article
Astronomy & Astrophysics
Reggie L. Hudson, Perry A. Gerakines, Yukiko Y. Yarnall, Ryan T. Coones
Summary: The study presents new IR spectra of hydrocarbon ices C3H8, C3H6, and C3H4, and reports measurements of ice density and refractive index for calculating IR absorption coefficients. Suggestions and interpretations on the multiple crystalline forms of propane and propylene are offered, along with descriptions of applications and extensions.
Article
Astronomy & Astrophysics
Reggie L. Hudson, Yukiko Y. Yarnall
Summary: The infrared spectra of benzene and pyridine in their amorphous and crystalline states were recorded. Measurements of density and refractive index were conducted to calculate the IR intensities and optical constants for laboratory experiments and astronomical observations. These measurements, made in a single laboratory, are the first to determine the density, refractive index, and spectra of these compounds at temperatures relevant to the outer solar system and interstellar medium. The results were used to determine the IR band strengths and optical constants of benzene and pyridine ices in their amorphous and crystalline forms. Comparisons were also made between the IR absorbance of benzene in samples with H2O-ice and anhydrous amorphous benzene.
Article
Astronomy & Astrophysics
M. Angrisani, E. Palomba, A. Longobardo, A. Raponi, F. Dirri, C. Gisellu
Summary: In this study, the composition and particle size of V-type asteroids were investigated through spectroscopic analysis. The researchers found possible chronological links between impact events on Vesta and the formation of V-type families. The results also suggest the presence of other basaltic parent bodies apart from Vesta.
Article
Astronomy & Astrophysics
Scot C. R. Rafkin, Juan M. Lora, Alejandro Soto, J. Michael Battalio
Summary: The deep convective cloud-environment feedback loop is crucial for understanding Titan's global methane, energy, and momentum cycles. This study uses cloud resolving modeling to quantify the effects of deep convective methane storms on their environment and improve parameterizations in global models.
Editorial Material
Microbiology
Elizabeth R. Ballou, Rebecca A. Drummond
Summary: In this study, a fungal morphotype uniquely adapted for extrapulmonary dissemination was identified, contributing to invasive infection and evasion of host immune responses.
CELL HOST & MICROBE
(2022)
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
Astronomy & Astrophysics
Sebastien Rodriguez, Sandrine Vinatier, Daniel Cordier, Gabriel Tobie, Richard K. Achterberg, Carrie M. Anderson, Sarah Badman, Jason W. Barnes, Erika L. Barth, Bruno Bezard, Nathalie Carrasco, Benjamin Charnay, Roger N. Clark, Patrice Coll, Thomas Cornet, Athena Coustenis, Isabelle Couturier-Tamburelli, Michel Dobrijevic, F. Michael Flasar, Remco de Kok, Caroline Freissinet, Marina Galand, Thomas Gautier, Wolf D. Geppert, Caitlin A. Griffith, Murthy S. Gudipati, Lina Z. Hadid, Alexander G. Hayes, Amanda R. Hendrix, Ralf Jaumann, Donald E. Jennings, Antoine Jolly, Klara Kalousova, Tommi T. Koskinen, Panayotis Lavvas, Sebastien Lebonnois, Jean-Pierre Lebreton, Alice Le Gall, Emmanuel Lellouch, Stephane Le Mouelic, Rosaly M. C. Lopes, Juan M. Lora, Ralph D. Lorenz, Antoine Lucas, Shannon MacKenzie, Michael J. Malaska, Kathleen Mandt, Marco Mastrogiuseppe, Claire E. Newman, Conor A. Nixon, Jani Radebaugh, Scot C. Rafkin, Pascal Rannou, Ella M. Sciamma-O'Brien, Jason M. Soderblom, Anezina Solomonidou, Christophe Sotin, Katrin Stephan, Darrell Strobel, Cyril Szopa, Nicholas A. Teanby, Elizabeth P. Turtle, Veronique Vuitton, Robert A. West
Summary: In response to ESA's Voyage 2050 announcement, the proposed POSEIDON mission aims to explore Saturn's largest moon, Titan, through joint orbital and in situ investigations. The mission aims to exceed the accomplishments of the Cassini-Huygens mission and explore Titan's northern latitudes in complement with NASA's upcoming Dragonfly mission. The ideal arrival time at Titan would be slightly before the next northern Spring equinox in 2039.
EXPERIMENTAL ASTRONOMY
(2022)
Article
Geosciences, Multidisciplinary
Ralph D. Lorenz
Summary: Saltation modeling by Comola et al. (2022) suggests smaller sand size and frequent sand transport on Titan, contradicting previous assumptions. The upcoming Dragonfly mission can test these predictions.
GEOPHYSICAL RESEARCH LETTERS
(2022)
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
Agata Rozek, Stephen C. Lowry, Benjamin Rozitis, Lord R. Dover, Patrick A. Taylor, Anne Virkki, Simon F. Green, Colin Snodgrass, Alan Fitzsimmons, Justyn Campbell-White, Sedighe Sajadian, Valerio Bozza, Martin J. Burgdorf, Martin Dominik, R. Figuera Jaimes, Tobias C. Hinse, Markus Hundertmark, Uffe G. Jorgensen, Penelope Longa-Pena, Markus Rabus, Sohrab Rahvar, Jesper Skottfelt, John Southworth
Summary: Between 2010 and 2017, new optical and radar observations of potentially hazardous asteroid (2102) Tantalus have been collected. The object appears to be nearly spherical with limited large-scale features. The spin-state is difficult to determine and the convex light curve-inversion model is more flattened. Radar measurements suggest possible variation in surface properties, while thermophysical analysis indicates a surface covered in fine-grained regolith. Further observations are needed to confirm these findings.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Review
Astronomy & Astrophysics
Andrew J. Ball, Thierry Blancquaert, Olivier Bayle, Leila Lorenzoni, Albert F. C. Haldemann
Summary: The Entry, Descent and Landing Demonstrator Module (EDM), part of the ESA-Roscosmos ExoMars 2016 mission, was a Mars lander that demonstrated various technologies. While the final touchdown and surface operation were not achieved, other aspects were successfully demonstrated through real-time telemetry data.
SPACE SCIENCE REVIEWS
(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
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
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
Lea E. Bonnefoy, Antoine Lucas, Alexander G. Hayes, Sebastien Rodriguez, Valerio Poggiali, Daniel E. Lalich, Ralph D. Lorenz, Alice Le Gall
Summary: This study utilizes radar imaging data from the Cassini spacecraft to map the Selk crater region on Titan. The results reveal variations in surface properties, indicating the exposure and fracturing of low-loss tangent materials, such as water-ice bedrock, due to impacts. The dunes and dark terrains are composed of smooth, uniform material with low dielectric constant, likely organic sand. This research provides valuable insights into the composition and geological history of Titan's surface.
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.