Search Publications
Multi-instrument analysis of electron populations in Saturn's magnetosphere
Schippers, P.; André, N.; Gurnett, D. A. +10 more
We analyze the radial distribution of electron populations inside 20 Rs in Saturn's magnetosphere, and we calculate moments for these populations by a forward modeling method using composite spectra produced by the CAPS/ELS (0.6 eV to 26 keV) and the MIMI/LEMMS (15 keV to 10 MeV) instruments on board Cassini. We first calculate and harm…
Electron temperature anisotropy constraints in the solar wind
Maksimovic, Milan; Marsch, Eckart; Scime, Earl E. +3 more
We have performed a statistical study of a substantial amount of electron data acquired in the solar wind to understand the constraints on electron temperature anisotropy by plasma instabilities and Coulomb collisions. We use a large data set of electron measurements from three different spacecraft (Helios I, Cluster II, and Ulysses) collected in …
Turbulence transport throughout the heliosphere
Matthaeus, W. H.; Bieber, J. W.; Smith, C. W. +4 more
We employ a turbulence transport model to compute distributions of turbulence throughout the heliosphere. The model determines the radial dependence of three (coupled) quantities that characterize interplanetary turbulence, the energy per unit mass, the cross helicity or Alfvénicity, and a similarity length scale. A fourth integrated quantity, the…
Electron density estimations derived from spacecraft potential measurements on Cluster in tenuous plasma regions
Sauvaud, J. -A.; Dandouras, I.; André, M. +13 more
Spacecraft potential measurements by the EFW electric field experiment on the Cluster satellites can be used to obtain plasma density estimates in regions barely accessible to other type of plasma experiments. Direct calibrations of the plasma density as a function of the measured potential difference between the spacecraft and the probes can be c…
An update to a Saturnian longitude system based on kilometric radio emissions
Gurnett, D. A.; Kurth, W. S.; Averkamp, T. F. +2 more
The period of Saturn kilometric radiation modulation as determined by Voyager forms the basis for a longitude system (SLS) recognized by the International Astronomical Union. However, Ulysses and Cassini observations have shown that this modulation period varies by the order of one percent on timescales of a few years and, hence, does not represen…
Warping of Saturn's magnetospheric and magnetotail current sheets
Coates, A. J.; Russell, C. T.; Dougherty, M. K. +5 more
The magnetotails of Jupiter and Earth are known to be hinged so that their orientation is controlled by the magnetic field of the planet at small distances and asymptotically approach the direction of the flow of the solar wind at large distances. In this paper we present Cassini observations showing that Saturn's magnetosphere is also similarly h…
Variation of the Martian ionospheric electron density from Mars Express radar soundings
Gurnett, D. A.; Morgan, D. D.; Plaut, J. J. +3 more
The Mars Advanced Radar for Subsurface and Ionospheric Sounding aboard Mars Express has been in operation for over 2 years. Between 14 August 2005 and 31 July 2007, we obtain 34,492 ionospheric traces, of which 14,060 yield electron density profiles and 12,291 yield acceptable fits to the Chapman ionospheric model. These results are used to study …
Properties of magnetosheath mirror modes observed by Cluster and their response to changes in plasma parameters
Dandouras, Iannis; Lucek, Elizabeth; Soucek, Jan
Mirror modes are large amplitude nonpropagating compressive structures frequently observed in the magnetosheath. They appear in the form of quasi-sinusoidal oscillations in the magnetic field, profound magnetic decreases (dips) or magnetic enhancements (peaks), accompanied by a corresponding anticorrelated signature in plasma density. In this stud…
Cassini plasma spectrometer thermal ion measurements in Saturn's inner magnetosphere
Thomsen, M. F.; Wilson, R. J.; Tokar, R. L. +3 more
Plasma data from the Cassini Plasma Spectrometer experiment are analyzed using a robust forward modeling technique for dayside equatorial orbits within the range 5.5 to 11 Saturn radii (1 RS = 60,268 km). It is assumed the measured ion data may be represented by two anisotropic Maxwellian distributed species, H+ and a water g…
Origin of Saturn's aurora: Simultaneous observations by Cassini and the Hubble Space Telescope
Coates, A. J.; Dougherty, M. K.; Nichols, J. D. +9 more
Outer planet auroras have been imaged for more than a decade, yet understanding their physical origin requires simultaneous remote and in situ observations. The first such measurements at Saturn were obtained in January 2007, when the Hubble Space Telescope imaged the ultraviolet aurora, while the Cassini spacecraft crossed field lines connected t…