Search Publications
Discovery of heavy negative ions in Titan's ionosphere
Lewis, G. R.; Coates, A. J.; Sittler, E. C. +3 more
Titan's ionosphere contains a rich positive ion population including organic molecules. Here, using CAPS electron spectrometer data from sixteen Titan encounters, we reveal the existence of negative ions. These ions, with densities up to ~100 cm-3, are in mass groups of 10-30, 30-50, 50-80, 80-110, 110-200 and 200+ amu/charge. During on…
Electron acceleration in the Van Allen radiation belts by fast magnetosonic waves
Meredith, Nigel P.; Horne, Richard B.; Glauert, Sarah A. +3 more
Local acceleration is required to explain electron flux increases in the outer Van Allen radiation belt during magnetic storms. Here we show that fast magnetosonic waves, detected by Cluster 3, can accelerate electrons between ∼10 keV and a few MeV inside the outer radiation belt. Acceleration occurs via electron Landau resonance, and not Doppler …
Evolution of the solar wind proton temperature anisotropy from 0.3 to 2.5 AU
Maksimovic, Milan; Landi, Simone; Hellinger, Petr +5 more
We report an analysis of the proton temperature anisotropy evolution from 0.3 to 2.5 AU based on the Helios and Ulysses observations. With increasing distance the fast wind data show a path in the parameter space (β $\parallel$ p , T $\perp$ p /T $\parallel$ p ). The first part of the trajectory is well describe…
Ultralow frequency modulation of energetic particles in the dayside magnetosphere
Balogh, A.; Zong, Q. -G.; Baker, D. N. +8 more
Energetic electron and ion (electrons: 30 keV to 500 keV, protons: 30 keV to 1.5 MeV) flux variations associated with ultralow frequency (ULF) waves in the dayside magnetosphere were observed during the CLUSTER's perigee pass near 0900 MLT on Oct. 31, 2003. The ULF modulation terminated where higher frequency fluctuations appeared, as the CLUSTER …
Pressurized oceans and the eruption of liquid water on Europa and Enceladus
Manga, M.; Wang, C. -Y.
It is difficult for liquid water to erupt onto the surface of icy satellites, such as Europa and Enceladus, because liquid water is more dense than ice. If the ice shell thickens, the volume expansion of ice upon freezing increases pressure in the subsurface ocean. The excess pressure is determined by a balance between compression of ocean water a…
Estimation of the total electron content of the Martian ionosphere using radar sounder surface echoes
Gim, Yonggyu; Kofman, Wlodek; Herique, Alain +5 more
The Martian ionosphere's local total electron content (TEC) and the neutral atmosphere scale height can be derived from radar echoes reflected from the surface of the planet. We report the global distribution of the TEC by analyzing more than 750,000 echoes of the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS). This is the fi…
A Saturnian longitude system based on a variable kilometric radiation period
Gurnett, D. A.; Kurth, W. S.; Averkamp, T. F. +2 more
This paper describes a longitude system for Saturn which is locked to the period of Saturn kilometric radiation. Because the apparent radio emission period varies with time, the period used in the system is allowed to vary. The resulting system results in the 'diurnal' peak of the radio emission occurring when the subsolar longitude is 100°, as wa…
Evidence for magnetic reconnection initiated in the magnetosheath
Eastwood, J. P.; Lucek, E. A.; Rème, H. +6 more
We report Cluster spacecraft 1 observations of a reconnection exhaust embedded in the magnetosheath flow. The reconnection evidence consists of (1) accelerated plasma outflows, (2) interpenetrating ion beams, (3) reconnection inflows and (4) the associated tangential reconnection electric field. Furthermore, Hall magnetic fields were observed with…
Nonstationarity and reformation of high-Mach-number quasiperpendicular shocks: Cluster observations
Dunlop, M.; Schwartz, S. J.; Krasnoselskikh, V. V. +3 more
A set of experimental data is presented for a high-Mach-number (M f = 5) quasiperpendicular ($\theta$ Bn = 81°) bow shock layer crossed by Cluster spacecraft on 24 January 2001 at 07:05-07:09 UT. The measurements of magnetic field, spectra of electric field fluctuations, and ion distributions reveal that the shock is high…
Strong rapid dipolarizations in Saturn's magnetotail: In situ evidence of reconnection
Russell, C. T.; Dougherty, M. K.; Jackman, C. M. +3 more
The oppositely directed magnetic field in the kronian magnetic tail is expected eventually to reconnect across the current sheet, allowing plasma to escape in an anti-solar direction down the tail. This reconnection process accelerates ions and electrons both toward and away from the planet, allowing the magnetotail to relax to a more dipolar conf…