Article
Geochemistry & Geophysics
Michael A. Calkins, Ryan J. Orvedahl, Nicholas A. Featherstone
Summary: The dynamics of convection-driven dynamos in a spherical shell, relevant to the geodynamo, were analyzed using numerical simulation data and asymptotic theory. The results showed that the Lorentz force is weaker than the mean buoyancy force across different Ekman numbers and thermal forcings, with a relative difference in forces of O(Ek(1/6)) within the investigated parameter space. The study also found that the mean zonal velocity scales as O(Ek(-1/3)), while the meridional circulation is asymptotically smaller by a factor of O(Ek(1/6)).
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
A. E. Stott, R. F. Garcia, A. Chedozeau, A. Spiga, N. Murdoch, B. Pinot, D. Mimoun, C. Charalambous, A. Horleston, S. D. King, T. Kawamura, N. Dahmen, S. Barkaoui, P. Lognonne, W. B. Banerdt
Summary: The SEIS experiment on the NASA InSight mission uses machine learning methods to analyze the relationship between weather data and seismic energy on Mars, detecting previously undetected marsquakes.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
Irene Bonati, Marine Lasbleis, Lena Noack
Summary: Research shows that the iron content of planets has a significant impact on core structure, evolution, and magnetic field lifetimes. Planets with high iron content may develop large solid inner cores, while massive planets with intermediate iron inventories have the longest dynamo lifetimes.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2021)
Article
Geochemistry & Geophysics
M. Puica, V Dehant, M. Folgueira, T. Van Hoolst, J. Rekier
Summary: The Earth's rotation is affected by gravitational torques from the Sun and the Moon, as well as angular momentum exchange with the atmosphere and hydrosphere. This study focuses on the influence of topography at the core-mantle boundary on variations in the length-of-day (LOD). Using an analytical approach, the researchers identify resonance frequencies and degrees of topographic coefficients that amplify tidal effects on LOD variations.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geosciences, Multidisciplinary
C. A. Denton, A. R. Rhoden
Summary: This article investigates the geology and internal evolution of Mimas, revealing the possibility of a liquid ocean and studying the formation of its major impact basin through simulations.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
C. Adeene Denton, Brandon C. Johnson, Shigeru Wakita, Andrew M. Freed, H. Jay Melosh, S. Alan Stern
Summary: Through simulating the impact that formed Sputnik Planitia, it was found that Pluto's interior may have included a subsurface ocean over 150 km thick and a hydrated core at the time of impact. The observed lineations antipodal to Sputnik Planitia may have been caused by significant deformation resulting from the impact.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Geochemistry & Geophysics
Sander Goossens, David E. Smith
Summary: The relationship between the degree of a spherical harmonic model of the gravitational field and the depth of a source expressed as a density contrast can be used to study the structure of features. The gravitational acceleration per spherical harmonic degree of a constant density source has an extremum dependent on source depth. The authors derive a degree-depth relationship using the spherical harmonics expansion for a point mass source and validate it with synthetic models.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Astronomy & Astrophysics
L. Affolter, C. Mordasini, A. V. Oza, D. Kubyshkina, L. Fossati
Summary: This study compares the results of an X-ray and extreme-ultraviolet (XUV)-driven energy-limited escape model with a direct hydrodynamic model. The hydrodynamic model, which includes more realistic treatment of cooling mechanisms, better reproduces the observed slope of the evaporation valley. The authors conclude that including boil-off and considering cooling effects is important for escape models. Overall, this study is significant for understanding atmospheric escape processes.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Geochemistry & Geophysics
H. C. F. C. Hay, I. Matsuyama, R. T. Pappalardo
Summary: This article investigates the tidal response model of Europa and Ganymede, considering ocean dynamics and the coupling effect with the ice shell. High-frequency tidal deformation is resonantly amplified by ocean dynamics, providing a unique determination of ocean thickness. This study is of great importance for understanding the thermal/orbital evolution of the moons.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2022)
Article
Astronomy & Astrophysics
J-M Hure
Summary: This article discusses the equilibrium conditions for a body made of two homogeneous components separated by oblate spheroidal surfaces and in relative motion. Exact solutions are not allowed for rigid rotation unless a specific ambient pressure is present, but approximations can be obtained for configurations involving a small confocal parameter. The problem has two families of solutions, depending on the pressure along the common interface. The analytical approach compares well with numerical solutions obtained from the self-consistent-field method and practical formulas are derived for slowly rotating star/planet interiors.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Environmental Sciences
Nancy J. Chanover, James M. Bauer, John J. Blalock, Mitchell K. Gordon, Lyle F. Huber, Mia J. T. Mace, Lynn D. V. Neakrase, Matthew S. Tiscareno, Raymond J. Walker
Summary: While fewer missions have been conducted to the outer Solar System compared to the inner Solar System, these missions to the giant planets have provided valuable data that continue to shape our understanding of these complex systems. The data are stored in national and international planetary archives and can be accessed through the NASA Planetary Data System (PDS). The PDS will serve as the main repository for future missions' data and support research on the interpretation of the existing data.
Article
Geochemistry & Geophysics
B. Thomas, H. Samuel, C. G. Farnetani, J. Aubert, C. Chauvel
Summary: This study investigates the efficiency of convective mixing in the Earth's mantle during the early molten and solid-state stages. By computing finite-time Lyapunov exponents, it is found that in a fully liquid magma ocean, the mixing time is short, suggesting that early mantle heterogeneities cannot survive.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Astronomy & Astrophysics
L. Allibert, S. Charnoz, J. Siebert, S. A. Jacobson, S. N. Raymond
Summary: This passage discusses the impact of collisional erosion on the composition of Earth and how it can provide information on the dynamical context of its formation. The composition of Earth's primitive mantle should be strictly chondritic, but there may be an excess of certain elements due to collisional erosion.
Article
Astronomy & Astrophysics
Hiroyuki Kurokawa, Yayoi N. Miura, Seiji Sugita, Yuichiro Cho, Francois Leblanc, Naoki Terada, Hiromu Nakagawa
Summary: Martian atmospheric neon can reflect the volatile content of the interior, with recent studies suggesting active volcanism on Mars and a much higher abundance of neon in the mantle compared to Earth. These findings provide important constraints on the abundance of other volatile elements in Mars' interior and its accretion history.
Article
Geochemistry & Geophysics
N. Compaire, L. Margerin, M. Monnereau, R. F. Garcia, L. Lange, M. Calvet, N. L. Dahmen, S. C. Staehler, N. Mueller, M. Grott, P. Lognonne, T. Spohn, W. B. Banerdt
Summary: This study investigates the seasonal variation of the near-surface properties on Mars using the SEIS seismometer. By analyzing background vibrations and high-frequency seismic events, the researchers found that the observed velocity changes can be adequately modeled by the thermoelastic response of the Martian regolith. Different seasons lead to different waveform characteristics.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)