Article
Geosciences, Multidisciplinary
M. A. Cordiner, G. L. Villanueva, H. Wiesemeyer, S. N. Milam, I. de Pater, A. Moullet, R. Aladro, C. A. Nixon, A. E. Thelen, S. B. Charnley, J. Stutzki, V. Kofman, S. Faggi, G. Liuzzi, R. Cosentino, B. A. McGuire
Summary: No evidence of atmospheric phosphine (PH3) was detected in the search for PH3 on Venus using the German REceiver for Astronomy at Terahertz Frequencies instrument.
GEOPHYSICAL RESEARCH LETTERS
(2022)
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.
Article
Astronomy & Astrophysics
Rohini S. Giles, Thomas K. Greathouse, Patrick G. J. Irwin, Therese Encrenaz, Amanda S. Brecht
Summary: High spectral resolution observations of Venus using the TEXES instrument revealed the vertical temperature profile and the three-dimensional structure of a planetary-scale thermal wave in Venus' atmosphere. These findings provide insights into the thermal tide propagation in the middle latitudes of Venus.
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
Yongliang Song, Xianyong Bai, Xu Yang, Wenda Cao, Han Uitenbroek, Yuanyong Deng, Xin Li, Xiao Yang, Mei Zhang
Summary: This study observed pores, quiet-Sun, and network magnetic field regions using CO 4.66μm lines and found the existence of CO cold bubbles. The role of magnetic fields in the generation of these cold bubbles was demonstrated through observations and simulations.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Roger Yelle, T. T. Koskinen, M. Y. Palmer
Summary: The study analyzed data from Titan's occultation of three stars in Orion's belt, revealing information on atmospheric composition, thermal structure, density distributions of different molecules, and aerosol extinction. Significant variations in latitude for certain molecules, aerosols, and temperature were found, providing insights into global circulation patterns. The inferred mole fractions of various molecules were consistent with photochemical model predictions, but with some overestimations and underestimations at different pressure levels.
Article
Astronomy & Astrophysics
J. Michael Battalio, Juan M. Lora, Scot Rafkin, Alejandro Soto
Summary: The influence of methane on the circulation of Titan is investigated using a simplified moist convection parameterization scheme. The results show that the reference relative humidity has a significant impact on convective instability and precipitation, while the relaxation timescale of convection has minor effects. The behavior of convection varies with the relative humidity, with infrequent and intense events at low relative humidity and near-continuous precipitation at high relative humidity during summer. Intermediate relative humidity values result in frequent events of moderate intensity.
Article
Geosciences, Multidisciplinary
F. Comola, J. F. Kok, J. M. Lora, K. Cohanim, X. Yu, C. He, P. McGuiggan, S. M. Horst, F. Turney
Summary: Titan, Saturn's largest moon, has huge linear dunes and an active dust cycle. Similar to Earth, these aeolian processes are caused by wind moving surface grains. However, it is still unclear how saltation can occur on Titan with its weak winds and potentially cohesive grains. This study suggests that saltation may occur on Titan through granular splash instead of aerodynamic lifting, and the prevailing circulation on Titan can generate significant yet intermittent saltation.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Engineering, Aerospace
Teyen Widdicombe, R. A. Borrelli
Summary: A pressure vessel was used to simulate the atmosphere of Titan and measure neutron attenuation. The results showed that the atmosphere and surface material have minimal impact on neutron measurements. This study confirms the accuracy of neutron modeling and concludes that neutrons from MMRTG are unlikely to affect Dragonfly's measurements on Titan's surface.
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
Darci Snowden, Alexandre Higgins
Summary: The study shows that Titan's induced magnetosphere is effective in shielding the atmosphere from thermal proton precipitation but only partially shields it from thermal oxygen precipitation. The energy deposited by thermal magnetospheric oxygen is lower than solar EUV input but similar to energy deposited by high energy neutral atoms and magnetospheric electrons.
Article
Environmental Sciences
Ruben Goncalves, Pedro Machado, Thomas Widemann, Francisco Brasil, Jose Ribeiro
Summary: Using Doppler velocimetry measurements, new insights into the horizontal wind velocities at Venus's cloud top were obtained, showing consistent zonal wind patterns and a stable meridional wind circulation structure.
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
Elise W. Knutsen, Geronimo L. Villanueva, Giuliano Liuzzi, Matteo M. J. Crismani, Michael J. Mumma, Michael D. Smith, Ann Carine Vandaele, Shohei Aoki, Ian R. Thomas, Frank Daerden, Sebastien Viscardy, Justin T. Erwin, Loic Trompet, Lori Neary, Bojan Ristic, Miguel Angel Lopez-Valverde, Jose Juan Lopez-Moreno, Manish R. Patel, Ozgur Karatekin, Giancarlo Bellucci
Summary: A comprehensive search for hydrocarbons in the Martian atmosphere conducted by the ExoMars Trace Gas Orbiter/NOMAD instrument from April 2018 to April 2019 did not yield any significant detections of organics, setting new stringent upper limits for global ethane and ethylene at 0.1 ppbv and 0.7 ppbv, respectively. No global background level of methane was observed, with an upper limit of 0.06 ppbv, in agreement with earlier findings. Dedicated searches for localized plumes at over 2000 locations also provided no positive detections, suggesting that methane release events, if they occur, are likely sporadic.
Article
Astronomy & Astrophysics
S. J. Kim, C. K. Sim, T. R. Geballe, Y. L. Yung, S. Miller, S. Lee, C. Tao
Summary: The 8-mu m CH4 north polar hot spot (8CNPHS) of Jupiter, detected in 1980, has been observed for four decades. Its shape and longevity are still not understood, but several mechanisms have been proposed. Recent observations suggest that the 8CNPHS is caused by transient and energetic magnetospheric particles that heat the hydrocarbon layers and energize the spot.
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.