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Astronomy & Astrophysics
Meir Shimon
Summary: In the standard cosmological model, the similarity between the densities of dark energy and nonrelativistic matter at the present time poses a cosmic coincidence problem. This study suggests that this coincidence can be explained as an observational selection effect and proposes a probability distribution function to describe it.
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Astronomy & Astrophysics
Jun Ge, Hong-Yun Nie, Kai-Ge Liu, Hao Li, Hai-Guan Lin, Tao Zhang, Hong-Wei Sun, Hong-Feng Yan, Jian-Wu Yang, Jin-Lian Zhou, Yan Cui
Summary: The study found that Kupffer cells (KCs) are sensitive to simulated microgravity (SMG). After 3 days of SMG treatment, transcriptome sequencing showed that 631 genes were upregulated while 801 genes were downregulated in KCs. GO analysis indicated that the proliferation of KCs was affected by SMG exposure for 3 days. CCK-8 assay confirmed that KC proliferation was inhibited on the third day under SMG. Furthermore, 8 key genes and 2 transcription factors that regulate these genes were identified.
LIFE SCIENCES IN SPACE RESEARCH
(2024)
Article
Astronomy & Astrophysics
M. Z. Bhatti, M. Yousaf, Z. Yousaf
Summary: The cut and paste approach is applied to construct static thin-shell wormhole models for a specific f(R, T) function. The stability and instability of the models are examined through theoretical and graphical approaches.
Article
Astronomy & Astrophysics
Bingcheng Suo, A. C. Quillen, Max Neiderbach, Luke O'Brient, Abobakar Sediq Miakhel, Nathan Skerrett, Jeremy Couturier, Victor Lherm, Jiaxin Wang, Hesam Askari, Esteban Wright, Paul Sanchez
Summary: In this study, oblique impacts into a granular medium (sand) at a velocity of 104 m/s were conducted. The impact craters showed nearly round rims even at a grazing angle of about 10 degrees. However, the strength of seismic pulses excited by the impact was found to be dependent on the impact angle, with the ratio between uprange and downrange velocity peaks reaching as high as 5.
Article
Astronomy & Astrophysics
Aster G. Taylor, Davide Farnocchia, David Vokrouhlicky, Darryl Z. Seligman, Jordan K. Stecklofff, Marco Micheli
Summary: Significant nonradial and nongravitational accelerations, which cannot be explained by radiation-driven effects, have been observed in seven photometrically inactive near-Earth objects. The study proposes that these accelerations can be explained by anisotropic outgassing resulting from differential heating on the nucleus of these objects. This explanation, although lacking confirmation of spin axes, provides a plausible mechanism for the observed accelerations and accurately perturbs the heliocentric motions of most of these objects.
Article
Astronomy & Astrophysics
Wendy K. Caldwell, Abigail Hunter, Catherine S. Plesko
Summary: Asteroid 16 Psyche, the largest metallic main belt asteroid, is the subject of research to determine its composition and porosity.
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
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
Atal Tewari, Vikrant Jain, Nitin Khanna
Summary: This research proposes a novel estimation and refinement-based approach to tackle the challenges of crater shape annotation and missing craters. By learning crater segmentation maps and refining them using deep learning networks, the method achieves better performance in crater detection.
Article
Astronomy & Astrophysics
V. Santiago Quinteros, Thomas Dylan Mikesell, Luke Griffiths, Alex X. Jerves
Summary: This study presents a comprehensive program of geotechnical index tests performed on two regolith simulants, providing detailed testing methodologies and comparing the results with existing data in the literature. The spread on the index tests results is explained by the indiscriminate use of different procedures and methodologies across different laboratories, highlighting the importance and urgency of agreeing on best practices in geotechnical testing of regolith and extra-terrestrial simulants.
Article
Astronomy & Astrophysics
Alexey A. Pankine, Nicholas G. Heavens, J. Michael Battalio, Corwin J. Wright
Summary: Gravity waves in the lower atmosphere of Mars play a crucial role in the planet's atmospheric dynamics and energy balance. Statistical analysis of observed brightness temperatures allows for the study of global gravity wave activity on Mars. Using data from the Mars Global Surveyor's Thermal Emission Spectrometer, researchers explore the spatial and seasonal variability of gravity wave activity at different scales. Results show that topography and seasons influence gravity wave activity, with a decrease in activity at higher altitudes and during global dust storms.
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.
Article
Astronomy & Astrophysics
Liliane M. L. Burkhard, Emily S. Costello, Bridget R. Smith-Konter, Marissa E. Cameron, Geoffrey C. Collins, Robert T. Pappalardo
Summary: Observations and investigations of the Nippur/Philus Sulci region on Ganymede reveal varying degrees of tectonic deformation and suggest that past higher eccentricity may have played a role in the formation of certain features. However, the en echelon folds found in a younger geologic unit may have formed through a different process.
Article
Astronomy & Astrophysics
Neha Panwar, Neeraj Srivastava
Summary: This study provides evidence for the influence of the proposed Australe North Basin on the local geology in the Scaliger Crater region. Late-stage volcanism has also been reported in this region, suggesting prolonged volcanic activity inside an obscured pre-Nectarian basin.
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
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
Zhiguo Meng, Hanning Sun, Zhaoran Wei, Yongzhi Wang, Xuan Feng, Yongchun Zheng, Zhanchuan Cai, Xiaoping Zhang, Alexander Gusev
Summary: This paper assesses the thermophysical properties of surface deposits in the Tsiolkovskiy crater using data from the Chang'E-2 mission. The results provide insights into the influence of topography on brightness temperature, suggest higher substrate temperatures in the southwest portion of the crater, identify two distinct episodes of mare deposits, and indicate the presence of centimeter-scale rocks beyond the crater.
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
B. Palmaerts, D. Grodent, B. Bonfond, Z. H. Yao, R. L. Guo, J. -c. Gerard, K. Haewsantati, G. R. Gladstone, T. K. Greathouse, V. Hue, J. D. Nichols
Summary: During the period between February and September 2019, the Hubble Space Telescope conducted a large-scale campaign to observe Jupiter's ultraviolet aurorae. The observations revealed the dynamic nature and complex structures of the aurorae, with the help of data from the Juno spacecraft and high-resolution images from HST.
Article
Astronomy & Astrophysics
Iraklis Giannakis, Anshuman Bhardwaj, Lydia Sam, Georgios Leontidis
Summary: Craters are important features in planetary exploration and can be automatically detected and estimated using machine learning and computer vision. However, existing models are limited to specific types of data and may not be reliable with data from different sources and setups. This paper presents a flexible crater detection scheme based on the Segment Anything Model (SAM), which can effectively identify and measure craters in various types of data and setups.
