Search Publications
Saturn's Deep Atmospheric Flows Revealed by the Cassini Grand Finale Gravity Measurements
Iess, L.; Guillot, T.; Miguel, Y. +4 more
How deep do Saturn's zonal winds penetrate below the cloud level has been a decades-long question, with important implications not only for the atmospheric dynamics but also for the interior density structure, composition, magnetic field, and core mass. The Cassini Grand Finale gravity experiment enables answering this question for the first time,…
Energy Range of Electron Rolling Pin Distribution Behind Dipolarization Front
Xu, Y.; Fu, H. S.; Burch, J. L. +4 more
The electron rolling pin distribution, showing electron pitch angles primarily at 0°, 90°, and 180°, has recently been observed behind dipolarization fronts (DFs) and explained using an analytical model. However, the energy range of such distribution has been unknown so far, owing to the low-resolution data in previous spacecraft missions. Here us…
The Onset and Growth of the 2018 Martian Global Dust Storm
Sánchez-Lavega, A.; Delcroix, M.; Hernández-Bernal, J. +1 more
We analyze the onset and initial expansion of the 2018 Martian Global Dust Storm (GDS 2018) using ground-based images in the visual range. This is the first case of a confirmed GDS initiating in the Northern Hemisphere. A dusty area extending about 1.4×105 km2 and centered at latitude +31.7°±1.8° and west longitude 18°±5°W in…
Effects of Ducting on Whistler Mode Chorus or Exohiss in the Outer Radiation Belt
Hanzelka, Miroslav; Santolík, Ondřej
Previously published statistics based on Cluster spacecraft measurements surprisingly show that in the outer radiation belt, lower band whistler mode waves predominantly propagate unattenuated parallel to the magnetic field lines up to midlatitudes, where ray tracing simulations indicated highly attenuated waves with oblique wave vectors. We expla…
Detection of Rotational Acceleration of Bennu Using HST Light Curve Observations
Emery, J. P.; Chesley, S. R.; Noll, K. S. +7 more
We observed the near-Earth asteroid (101955) Bennu from the ground in 1999 and 2005, and with the Hubble Space Telescope (HST) in 2012, to constrain its rotation rate. The data reveal an acceleration of 2.64 ± 1.05 × 10-6 deg/day2, which could be due to a change in the moment of inertia of Bennu or to spin up from the Yarkovs…
Plasma Pressures in the Heliosheath From Cassini ENA and Voyager 2 Measurements: Validation by the Voyager 2 Heliopause Crossing
Krimigis, Stamatios M.; Mitchell, Donald G.; Dialynas, Konstantinos +1 more
We report "ground truth," 28- to 3,500-keV in situ ion and 5.2- to 55-keV remotely sensed ENA measurements from Voyager 2/Low Energy Charged Particle detector and Cassini/Ion and Neutral Camera, respectively, that assess the components of the ion pressure in the heliosheath. In this process, we predict an interstellar neutral hydrogen density of ∼…
Multispacecraft Analysis of Electron Holes
Russell, C. T.; Vaivads, A.; Khotyaintsev, Yu. V. +4 more
Electron holes (EHs) are nonlinear electrostatic structures in plasmas. Most previous in situ studies of EHs have been limited to single- and two-spacecraft methods. We present statistics of EHs observed by Magnetospheric Multiscale on the magnetospheric side of the magnetopause during October 2016 when the spacecraft separation was around 6 km. E…
Combined Scattering of Radiation Belt Electrons Caused by Landau and Bounce Resonant Interactions With Magnetosonic Waves
Fu, Song; Ni, Binbin; Gu, Xudong +2 more
We develop a full relativistic test particle code to model the combined electron scattering effect of Landau and bounce resonances with magnetosonic waves. Test particle simulations of magnetosonic wave-electron interactions indicate that the two resonances coexist to affect radiation belt electrons at different energies and pitch angles, and the …
The Effects of Solar Wind Dynamic Pressure on the Structure of the Topside Ionosphere of Mars
Gurnett, D. A.; Morgan, D. D.; Kopf, A. J. +3 more
We use Mars Atmosphere and Volatile EvolutioN observations of the upstream solar wind, and Mars Express observations of ionospheric electron densities and magnetic fields, to study how the topside ionosphere (>320 km) of Mars is affected by variations in solar wind dynamic pressure. We find that high solar wind dynamic pressures result in the t…
Evidence of Magnetic Nulls in the Reconnection at Bow Shock
Wang, Z.; Xu, Y.; Fu, H. S. +2 more
Magnetic nulls are believed to play important roles in the energy dissipation during reconnection. Such nulls have been observed in reconnection at the magnetopause, magnetosheath, and magnetotail but have never been observed in reconnection at the bow shock. Recently, four reconnection events were reported at the terrestrial bow shock, by utilizi…