Article
Astronomy & Astrophysics
D. Yan, R. C. Qiao, H. Y. Zhang, Y. Yu
Summary: In this study, the astrometric positions of the seven main satellites of Saturn were obtained and compared to theoretical positions. The results show small differences among the three planetary ephemerides.
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
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
D. M. Weigt, W. R. Dunn, C. M. Jackman, R. Kraft, G. Branduardi-Raymont, J. D. Nichols, A. D. Wibisono, M. F. Vogt, G. R. Gladstone
Summary: In this study, X-ray observations of Saturn were conducted by Chandra to analyze the magnetospheric response of Saturn during its passage through Jupiter's 'flapping' magnetotail. No significant detection of Saturn's auroral or disc emissions was found, with implications discussed on the importance of future X-ray telescopes with improved resolution and sensitivity for further investigation into Saturn's elusive X-ray auroras.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
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
M. Yu. Khovritchev, V. Robert, N. V. Narizhnaya, T. A. Vasilyeva, A. A. Apetyan, D. A. Bikulova
Summary: Old photographic plates were reprocessed to obtain positions of Saturnian moons in the Gaia DR2 system with unprecedented accuracy. The digitized astronegatives were calibrated and analyzed, revealing faint systematic effects in satellite motion theories.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
D. A. Patthoff, R. T. Pappalardo, M. Golombek, H. Chilton, E. Crow-Willard, P. C. Thomas
Summary: Several large ridges on Saturn's icy moon Enceladus suggest that they may have been formed through processes similar to those on terrestrial planets. The ridges are possibly thrust blocks and show signs of recent high heat flow.
Article
Astronomy & Astrophysics
Alice C. Quillen, Fatima Zaidouni, Miki Nakajima, Esteban Wright
Summary: The study explores scenarios for the formation of ornamental ridges on Saturn's moons Pan, Atlas, and Daphnis, suggesting that complex-shaped ridges, such as sloped and lobed ridges, may form due to changes in the moon's shape during accretion. Additionally, the possibility of accretion from asymmetric gaps in the rings is considered, which could lead to the formation of multiple lobes on the moons.
Article
Astronomy & Astrophysics
L. A. Sromovsky, K. H. Baines, P. M. Fry
Summary: Saturn's north polar region experienced significant changes between 2012 and 2017, particularly in the color shift from dark blue/green to gold in the hexagon region, which can be attributed to alterations in aerosol layers. Spectral observations also revealed the presence of small bright cloud features in the ammonia cloud layer, with varying aerosol optical depths in different areas.
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
K. Dapre, J. C. E. Irving
Summary: This study investigates the effects of ice shell and ocean thickness, as well as core structure and composition, on the waveforms recorded by a single seismometer for three 1D models of Enceladus. The results suggest that core-transmitted and -reflected phases can be observed even at low epicentral distances, providing constraints on ocean depth and core structure.
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
S. G. Jarmak, T. M. Becker, J. E. Colwell, R. G. Jerousek, L. W. Esposito
Summary: This article presents a dataset and high-level data products from the UVIS instrument on the Cassini spacecraft, which observed solar and stellar occultations to study Saturn's rings. The products include light curves, optical depth profiles, and provide insights into the properties of Saturn's rings.
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
Shea N. Thorne, Catherine L. Johnson, Anna Mittelholz, Benoit Langlais, Ralph Lorenz, Naomi Murdoch, Aymeric Spiga, Suzanne E. Smrekar, W. Bruce Banerdt
Summary: The NASA InSight lander has recorded pressure drops attributed to convective vortices. However, dust-carrying vortices have not been observed in InSight images. The study examines if magnetic signals are associated with daytime vortices and finds a small proportion of pressure drop events showing significant magnetic field signals, with no clear correlation.
PLANETARY AND SPACE SCIENCE
(2022)
Article
Geosciences, Multidisciplinary
Baptiste Chide, Tanguy Bertrand, Ralph D. Lorenz, Asier Munguira, Ricardo Hueso, Agustin Sanchez-Lavega, German Martinez, Aymeric Spiga, Xavier Jacob, Manuel de la Torre Juarez, Mark T. Lemmon, Don Banfield, Claire E. Newman, Naomi Murdoch, Alexander Stott, Daniel Viudez-Moreiras, Jorge Pla-Garcia, Carene Larmat, Nina L. Lanza, Jose Antonio Rodriguez-Manfredi, Roger C. Wiens
Summary: Acoustic measurements on Mars reveal previously unreported rapid fluctuations in atmospheric temperatures, indicating the presence of turbulence in the lower part of the planetary boundary layer.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Review
Geochemistry & Geophysics
J. Judson Wynne, John E. Mylroie, Timothy N. Titus, Michael J. Malaska, Debra L. Buczkowski, Peter B. Buhler, Paul K. Byrne, Glen E. Cushing, Ashley Gerard Davies, Amos Frumkin, Candice Hansen-Koharcheck, Victoria Hiatt, Jason D. Hofgartner, Trudi Hoogenboom, Ulyana Horodyskyj, Kynan Hughson, Laura Kerber, Margaret Landis, Erin J. Leonard, Elodie Lesage, Alice Lucchetti, Matteo Massironi, Karl L. Mitchell, Luca Penasa, Cynthia B. Phillips, Riccardo Pozzobon, Jani Radebaugh, Francesco Sauro, Robert V. Wagner, Thomas R. Watters
Summary: This article provides a comprehensive overview of speleogenic processes and features across the solar system. By examining 15 solar system bodies, six different types of cave-forming processes were identified, and 3,545 subsurface access points (SAPs) were identified on 11 planetary bodies and four additional bodies. The majority of knowledge on extraterrestrial SAPs is based on global databases for the Moon and Mars, with high-resolution imagery and other data available. Future research will require acquiring high-resolution imagery to further characterize features beyond the Moon 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
Aaron A. Morrison, Alan G. Whittington, Karl L. Mitchell
Summary: Cryovolcanism is proposed as an explanation for features observed on icy bodies, with similarities to volcanic features on Earth. The existing models from volcanology and hydrology do not fully capture the flow emplacement of cryolava. A new model was developed in this study to track the evolution of a hypothetical H2O-NaCl flow on an Europa-like body, which provides insights into the physical, chemical, and thermal states of cryolava flow.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Astronomy & Astrophysics
Richard H. Chen, Roger J. Michaelides, Yuhuan Zhao, Lingcao Huang, Elizabeth Wig, Taylor D. Sullivan, Andrew D. Parsekian, Howard A. Zebker, Mahta Moghaddam, Kevin M. Schaefer
Summary: Seasonal subsidence induced by ground ice melt can provide valuable information about active layer thickness (ALT) in permafrost regions. This study combined L-band InSAR subsidence and P-band PolSAR backscatter to simultaneously estimate ALT and soil moisture profile. The joint retrieval approach has been applied to SAR data acquired during the 2017 Arctic-Boreal Vulnerability Experiment, providing regional estimates of ALT and soil moisture profile for the ABoVE study domain.
EARTH 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)
Meeting Abstract
Acoustics
Louise L. Zhuang, Jeremy Dahl, Howard Zebker, Marko Jakovljevic
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA
(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
Engineering, Electrical & Electronic
Stacey A. Huang, Howard A. Zebker
Summary: Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) is a remote sensing technique that accurately maps patterns of crustal deformation. This study introduces a novel PS detector (NG detector) that accounts for the non-Gaussian nature of radar backscatter, and demonstrates its superior performance compared to traditional Gaussian models with two case studies. The NG detector identifies more persistent scatterers in both areas and accurately tracks deformation measured by GPS in the Central Valley.
IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING
(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.