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
Davide Sulcanese, Camilla Cioria, Osip Kokin, Giuseppe Mitri, Monica Pondrelli, Gianluca Chiarolanza
Summary: The surface of Triton is shaped by various endogenic processes like tectonism, volcanism, diapirism, and geyser-like eruptions. A geological analysis of the Monad Regio area was conducted to understand how these processes have influenced the surface. By analyzing Voyager images, a digital elevation model, and a roughness map, a geomorphological map was created to accurately identify known and new landforms. The study also revealed a sequence of endogenic and exogenic processes, including depositional and erosional events involving ice and liquid nitrogen flow.
Article
Geosciences, Multidisciplinary
Rui Wang, Jimmy C. H. Fung, Alexis K. H. Lau
Summary: Precise and timely rainfall nowcasting is crucial for ensuring public safety during heavy precipitation-induced disasters. However, the effectiveness of deep-learning models in nowcasting is still hindered by limited forecasting skill, insufficient training data, and escalating blurriness in forecasts. To address these challenges, we propose the Synthetic-data Task-segmented Generative Model (STGM), which demonstrates promising skill for precipitation forecasts up to six hours and significantly reduces the blurriness of predicted images.
GEOPHYSICAL RESEARCH LETTERS
(2023)
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
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.
Article
Astronomy & Astrophysics
Alice A. Le Gall, Lea E. Bonnefoy, Robin Sultana, Cedric Leyrat, Michael. A. Janssen, Stephen Wall, Emmanuel Lellouch
Summary: Through the distant observations of the Cassini spacecraft's RADAR, the purity and maturity of Saturn's icy moons' regoliths were investigated. The study found that Enceladus has the cleanest regolith, while the regoliths of other moons become less pure as they move outward from Enceladus. The variations in microwave signatures are primarily attributed to the different levels of contamination in the regolith.
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
Geosciences, Multidisciplinary
Philip D. Gingerich
Summary: Rates are widely used in geological sciences to characterize processes, with the numerator representing change or difference and the denominator corresponding to an interval of time. Temporal scaling examines the relationship between differences, rates, and their associated time intervals, often analyzed on logarithmic axes. Geological studies commonly involve rates dependent on denominators due to observed changes being constrained to a narrower range compared to the longer spans of geological time. When rates are dependent on denominators, comparisons must be made on a common scale of time.
EARTH-SCIENCE REVIEWS
(2021)
Article
Astronomy & Astrophysics
Jason C. Cook, Silvia Protopapa, Cristina M. Dalle Ore, Dale P. Cruikshank, William M. Grundy, Carey M. Lisse, Bernard Schmitt, Anne Verbiscer, Kelsi N. Singer, John Spencer, S. Alan Stern, Harold A. Weaver
Summary: In this study, we examined the 2.21-mu m band of Charon using data obtained by New Horizons/LEISA. We found no significant variation in this band as Charon rotates. The 2.21-mu m band on Charon is several times weaker than on other moons, and we attribute it to NH4Cl based on the appearance of a weaker band at 2.24-mu m. Additionally, we observed two never-before-reported absorption features in Charon's spectrum at 1.60 and 1.63-mu m, which may also be explained by the presence of NH4Cl. If NH3-H2O ice mixtures are present on Charon, they must be a small fraction of the overall composition.
Article
Engineering, Aerospace
S. Prabu, P. Hancock, X. Zhang, S. J. Tingay, T. Hodgson, B. Crosse, M. Johnston-Hollitt
Summary: In this paper, two methods, namely shift-stacking and phase correction, are demonstrated to improve the detection sensitivity of the Murchison Widefield Array (MWA) in the Low Earth Orbit (LEO) environment. These methods have been successfully tested in previous observations and an observation of the International Space Station (ISS) pass. The paper also discusses the expected sensitivity improvement from the MWA Phase 3 correlator upgrade and the future integration of MWA technologies into dedicated Space Domain Awareness (SDA) systems.
ADVANCES IN SPACE RESEARCH
(2022)
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)
Editorial Material
Geochemistry & Geophysics
Ralph D. Lorenz
Summary: New analysis of Cassini radar altimeter data reveals the depth and composition of Moray Sinus, an inlet at the northern margin of Titan's largest sea, Kraken Mare. The absence of a bottom echo on Kraken Mare suggests it may be very deep, ethane-rich, or both. This research provides insight into Titan's seas and climate.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2021)
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
D. Takir, M. Matsuoka, A. Waiters, H. Kaluna, T. Usui
Summary: By measuring the near-infrared reflectance spectra of Phobos and Deimos, this study aims to investigate their surface composition and mineralogical absorption signatures. Evidence of hydration was found in Deimos' LXD spectra, possibly attributed to exogenic or endogenic sources. However, no absorption signatures of mafic silicates, organics, or carbonates were observed in the prism and LXD spectra of Phobos and Deimos.
Article
Geochemistry & Geophysics
Nazzareno Pierdicca, Marco Brogioni, Fabio Fascetti, Jeffrey D. Ouellette, Leila Guerriero
Summary: Bistatic and multistatic radar observations focus on exploiting both signal phase and amplitude, aiming to improve the accuracy of inverse problem resolution by combining independent observations. Suitable geometrical configurations of passive satellite radar flying in convoy with an active spaceborne SAR at L-band can enhance retrieval performances for soil moisture and vegetation biomass estimation. By combining monostatic and bistatic measurements in geometric configurations requiring large baselines, the scattering mechanisms involved in different geometries lead to improved retrieval performances compared to monostatic acquisitions.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2022)
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
Astronomy & Astrophysics
Thierry Fouchet, Jean-Michel Reess, Franck Montmessin, Rafik Hassen-Khodja, Napoleon Nguyen-Tuong, Olivier Humeau, Sophie Jacquinod, Laurent Lapauw, Jerome Parisot, Marion Bonafous, Pernelle Bernardi, Frederic Chapron, Alexandre Jeanneau, Claude Collin, Didier Zeganadin, Patricia Nibert, Sadok Abbaki, Christophe Montaron, Cyrille Blanchard, Vartan Arslanyan, Ourdya Achelhi, Claudine Colon, Clement Royer, Vincent Hamm, Mehdi Beuzit, Francois Poulet, Cedric Pilorget, Lucia Mandon, Olivier Forni, Agnes Cousin, Olivier Gasnault, Paolo Pilleri, Bruno Dubois, Cathy Quantin, Pierre Beck, Olivier Beyssac, Stephane Le Mouelic, Jeffrey R. Johnsson, Timothy H. McConnochie, Sylvestre Maurice, Roger C. Wiens
Summary: This article presents the Infrared spectrometer of SuperCam Instrument Suite, which allows the Mars 2020 Perseverance Rover to study Martian mineralogy in the Jezero crater remotely. The SuperCam IR spectrometer is designed to acquire spectra in the 1.3-2.6 μm range with high spectral resolution. It works in conjunction with other remote sensing techniques to explore the mineral diversity and guide the sampling tasks of the Perseverance Rover.
Article
Geochemistry & Geophysics
C. Perrin, A. Jacob, A. Lucas, R. Myhill, E. Hauber, A. Batov, T. Gudkova, S. Rodriguez, P. Lognonne, J. Stevanovi, M. Drilleau, N. Fuji
Summary: The NASA InSight mission to Mars has successfully landed on the planet and has provided valuable information about seismic activity and the internal structure. Detailed mapping of the Cerberus Fossae region has revealed important morphological features related to tectonic activity, contributing to a better understanding of the geological processes on Mars.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2022)
Article
Geosciences, Multidisciplinary
Ping Lu, Clement Narteau, Zhibao Dong, Philippe Claudin, Sebastien Rodriguez, Zhishan An, Cyril Gadal, Sylvain Courrech du Pont
Summary: In this study, landscape-scale experiments conducted at the edge of the Gobi desert demonstrate the simultaneous development of various dune types under natural wind conditions. The researchers also found that the same wind regime can lead to two different dune orientations depending on sand availability, suggesting two independent dune growth mechanisms. The experimental field observations support existing theoretical models of dune dynamics, boosting confidence in their ability to predict dune evolution under different wind regimes and bed conditions.
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
Geochemistry & Geophysics
Patrick J. J. Gasda, Jade Comellas, Ari Essunfeld, Debarati Das, Alexander B. B. Bryk, Erwin Dehouck, Susanne P. P. Schwenzer, Laura Crossey, Kenneth Herkenhoff, Jeffrey R. R. Johnson, Horton Newsom, Nina L. L. Lanza, William Rapin, Walter Goetz, Pierre-Yves Meslin, John C. C. Bridges, Ryan Anderson, Gael David, Stuart M. R. Turner, Michael T. T. Thorpe, Linda Kah, Jens Frydenvang, Rachel Kronyak, Gwenael Caravaca, Ann Ollila, Stephane Le Mouelic, Matthew Nellessen, Megan Hoffman, Deirdra Fey, Anges Cousin, Roger C. C. Wiens, Samuel M. M. Clegg, Sylvestre Maurice, Olivier Gasnault, Dorothea Delapp, Adriana Reyes-Newell
Summary: Researchers analyzed diagenetic features in the clay-rich Glen Torridon region of Mars' Gale crater, finding evidence for multiple generations of fluids and a wide range of chemical reactions. These discoveries provide strong evidence for habitability of groundwater in Gale crater and have implications for prebiotic chemistry in early Mars.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2022)
Article
Geochemistry & Geophysics
Erwin Dehouck, Agnes Cousin, Nicolas Mangold, Jens Frydenvang, Olivier Gasnault, Olivier Forni, William Rapin, Patrick J. Gasda, Gwenael Caravaca, Gael David, Candice C. Bedford, Jeremie Lasue, Pierre-Yves Meslin, Kristin Rammelkamp, Marine Desjardins, Stephane Le Mouelic, Michael T. Thorpe, Valerie K. Fox, Kristen A. Bennett, Alexander B. Bryk, Nina L. Lanza, Sylvestre Maurice, Roger C. Wiens
Summary: Glen Torridon is a topographic trough on Mars with relatively strong spectral signatures of clay minerals. The Curiosity rover explored the area for over 700 Martian days to understand the geologic context of clay mineral formation and determine the intensity of aqueous alteration. Analysis of the bedrock's major-element geochemistry reveals distinct chemical compositions and mineralogical interpretations. Overall, the alteration in Glen Torridon shows elevated Chemical Index of Alteration values, suggesting the formation of clay minerals through open-system weathering.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2022)
Article
Geochemistry & Geophysics
C. Royer, T. Fouchet, L. Mandon, F. Montmessin, F. Poulet, O. Forni, J. R. Johnson, C. Legett, S. Le Mouelic, O. Gasnault, C. Quantin-Nataf, P. Beck, E. Dehouck, E. Clave, A. M. Ollila, C. Pilorget, P. Bernardi, J. -M. Reess, P. Pilleri, A. Brown, R. T. Newell, E. Cloutis, S. Maurice, R. C. Wiens
Summary: The Mars 2020 Perseverance rover successfully landed on the Jezero crater, where it will search for evidence of past Martian life. The SuperCam instrument, an international collaboration, will play a crucial role in this mission by providing high-quality mineralogy, chemistry, and color imaging data. The instrument's infrared spectrometer has been calibrated using observations of the Aluwhite SuperCam Calibration Target, allowing scientists to study the 2.5 μm absorption band associated with phyllosilicates-carbonates mixtures in the Seitah unit.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
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
Geochemistry & Geophysics
L. Mandon, C. Quantin-Nataf, C. Royer, P. Beck, T. Fouchet, J. R. Johnson, E. Dehouck, S. Le Mouelic, F. Poulet, F. Montmessin, C. Pilorget, O. Gasnault, O. Forni, L. E. Mayhew, O. Beyssac, T. Bertrand, E. Clave, P. Pinet, A. J. Brown, C. Legett, J. Tarnas, E. A. Cloutis, G. Poggiali, T. Fornaro, S. Maurice, R. C. Wiens, SuperCam Team
Summary: The Perseverance rover examined the mineralogy of the rocks, regolith, and dust in the Jezero crater on Mars. It found that the bedrock contains olivine-bearing rocks at the bottom and high-Ca pyroxene-bearing rocks at the top, suggesting an igneous origin. Aqueous alteration was detected in most of the rocks, indicating widespread but limited alteration of the crater floor. The diverse mineralogy suggests at least two stages of aqueous alteration, forming phyllosilicates and oxyhydroxides, and later sulfates.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Astronomy & Astrophysics
M. Es-sayeh, S. Rodriguez, M. Coutelier, P. Rannou, B. Bezard, L. Maltagliati, T. Cornet, B. Grieger, E. Karkoschka, S. Le Mouelic, A. Le Gall, C. Neish, S. MacKenzie, A. Solomonidou, C. Sotin, A. Coustenis
Summary: This study analyzed data from the Cassini spacecraft's Visual and Infrared Mapping Spectrometer (VIMS) to study the surface composition and landscape formation of the Selk crater region on Titan. The results suggest that the mountainous terrains in the area are likely dominated by fine grains of organic sediment, which may be transported to the lowlands by rivers and deposited as sand particles. These findings are important for the preparation of the Dragonfly mission and future exploration of Titan's surface composition and geology.
PLANETARY SCIENCE JOURNAL
(2023)
Article
Geochemistry & Geophysics
Allan H. Treiman, Nina L. Lanza, Scott VanBommel, Jeff Berger, Roger Wiens, Thomas Bristow, Jeffrey Johnson, Melissa Rice, Reginald Hart, Amy McAdam, Patrick Gasda, Pierre-Yves Meslin, Albert Yen, Amy J. Williams, Ashwin Vasavada, David Vaniman, Valerie Tu, Michael Thorpe, Elizabeth D. Swanner, Christina Seeger, Susanne P. Schwenzer, Susanne Schroeder, Elizabeth Rampe, William Rapin, Silas J. Ralston, Tanya Peretyazhko, Horton Newsom, Richard V. Morris, Douglas Ming, Matteo Loche, Stephane Le Mouelic, Christopher House, Robert Hazen, John P. Grotzinger, Ralf Gellert, Olivier Gasnault, Woodward W. Fischer, Ari Essunfeld, Robert T. Downs, Gordon W. Downs, Erwin Dehouck, Laura J. Crossey, Agnes Cousin, Jade M. Comellas, Joanna V. Clark, Benton Clark III, Steve Chipera, Gwenael Caravaca, John Bridges, David F. Blake, Ryan Anderson
Summary: The MSL Curiosity rover discovered manganese-phosphorus nodules on Mars, which were formed from vivianite and went through mineralogical transformations to laueite/strunzite and eventually to hematite and pyrolusite.
Article
Astronomy & Astrophysics
N. W. Kutsop, A. G. Hayes, P. M. Corlies, S. Le Mouelic, J. I. Lunine, C. A. Nixon, P. Rannou, S. Rodriguez, M. T. Roman, C. Sotin, T. Tokano
Summary: We analyzed data from the Cassini spacecraft to understand the characteristics and changes of the circumglobal annuli in the stratosphere of Titan. The annuli were observed at different latitudes, with dark and bright regions. We also observed the presence of a south polar annulus, although it was not detected by the Cassini spacecraft. The stratosphere appears to rotate around the north pole or a point slightly offset from the solid-body rotation axis.
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.