Search Publications
Understanding the escape of water from Enceladus
Johnson, R. E.; Sittler, E. C.; Smith, H. T. +3 more
On 14 July 2005, Cassini passed within 175 km of Enceladus' surface enabling a direct in situ measurement of water escaping from the surface by the Ion and Neutral Mass Spectrometer (INMS) and the observation of a stellar occultation by the Ultraviolet Spectrometer (UVIS). We have developed a three-dimensional, Monte Carlo neutral model to simulta…
Thinning and stretching of the plasma sheet
Petrukovich, A. A.; Balogh, A.; RèMe, H. +3 more
With Cluster observations in the magnetotail we study dynamics of plasma sheet thinning and stretching during 39 intervals associated with substorm growth phases. The cross-tail current density and normal magnetic field generally scale as Bn ∼ TpNp1/2/J0, but with frequent transient variations…
Electron sources in Saturn's magnetosphere
André, N.; Coates, A. J.; Dougherty, M. K. +11 more
We investigate the sources of two different electron components in Saturn's inner magnetosphere (5 < L < 12 Rs) by performing phase space density (f(v)) analyses of electron measurements made by the Cassini CAPS instrument (1 eV to 28 keV). Because pitch angle distributions indicate that the traditional single particle invariants of gyration…
Response of Jupiter's UV auroras to interplanetary conditions as observed by the Hubble Space Telescope during the Cassini flyby campaign
Nichols, J. D.; Clarke, J. T.; Cowley, S. W. H. +4 more
We provide a first detailed discussion of the relation between the set of Jovian UV auroral images observed by the Hubble Space Telescope (HST) in December 2000 to January 2001 and simultaneous interplanetary data obtained by Cassini during its Jupiter flyby. Examination of the interplanetary data surrounding all seven HST observation intervals sh…
Spontaneous axisymmetry breaking of the external magnetic field at Saturn
Goldreich, Peter; Farmer, Alison J.
Saturn's magnetic field is remarkably axisymmetric. Early evidence for nonaxisymmetry came from the periodicity of Saturn's kilometric radio bursts (SKR). Subsequently, percent-level variations of the SKR period were found to occur on timescales of years. A recent breakthrough has been the direct detection of a nonaxisymmetric component of the fie…
Electron microdiffusion in the Saturnian radiation belts: Cassini MIMI/LEMMS observations of energetic electron absorption by the icy moons
Krupp, N.; Woch, J.; Dougherty, M. K. +7 more
Since Saturn orbit insertion (SOI), Cassini has performed numerous crossings of Saturn's inner moons' L shells. The Low-Energy Magnetospheric Measurement System (LEMMS) has detected a large number of microsignatures in its lowest-energy electron channels (20-100 keV) as well as in the MeV energy range. We have catalogued and analyzed more than 70 …
Magnetic field rotation analysis and the applications
Lucek, E.; Dunlop, M.; Liu, Z. X. +4 more
An analysis technique, termed MRA (magnetic rotation analysis), has been designed to probe three-dimensional magnetic field topology. It is based on estimating the gradient tensor of four-point measurements of the magnetic field which have been taken by the Cluster mission. The method first constructs the symmetrical magnetic rotation tensor and i…
Mass loading of Saturn's magnetosphere near Enceladus
Dougherty, Michele K.; Russell, Christopher T.; Khurana, Krishan K. +1 more
The Cassini spacecraft has made three close flybys of Enceladus. The magnetic field from the first flyby clearly showed that Enceladus acts as an obstacle to the magnetized flow resulting in field line draping. The second flyby confirmed the draping pattern but hinted that the effective source must be located below Enceladus and demonstrated that …
Three-dimensional global simulation of interplanetary coronal mass ejection propagation from the Sun to the heliosphere: Solar event of 12 May 1997
Wu, S. T.; Dryer, M.; Fry, C. D. +2 more
A newly developed hybrid code, HAFv.2+3DMHD, that combines two simulation codes, Hakamada-Akasofu-Fry code version 2 (HAFv.2) and a fully three-dimensional (3-D), time-dependent MHD simulation code, is used to study the global interplanetary coronal mass ejection (ICME) from the 12 May 1997 solar event. The solar wind structure is first simulated …
Charged particle periodicities in Saturn's outer magnetosphere
Krupp, N.; Krimigis, S. M.; Mitchell, D. G. +2 more
A Lomb periodogram analysis is applied to charged particle data from the LEMMS/CHEMS instruments on the Cassini spacecraft. The data represent count rates, averaged within 30 min bins, from electrons (28-330 keV) and protons and oxygen ions (2.8-236 keV) during 350 days in 2005 and all 365 days in 2006. Sun effects, spacecraft maneuvers, and measu…