Search Publications
A nightside source of Saturn's kilometric radiation: Evidence for an inner magnetosphere energy driver
Gurnett, D. A.; Kurth, W. S.; Cecconi, B. +5 more
During Cassini's orbit insertion about Saturn, the spacecraft passed within 1.4 Rs of the planet passing from dayside into the nightside region. During this nightside passage, the onboard Radio and Plasma Wave (RPWS) instrument surprisingly detected Saturn kilometric radiation (SKR). Prior to this encounter, it was believed that SKR ori…
Cluster electron observations of the separatrix layer during traveling compression regions
Balogh, A.; Fazakerley, A. N.; Owen, C. J. +2 more
We present Cluster 4-point observations of electrons during traveling compression regions (TCRs) on 19 September 2001. The electron and |B| signatures vary with distance from the plasma sheet, confirming that transient plasma sheet bulges propagate past Cluster. TCRs with |B| increases have either no electron signature, or unidirectional ~1 keV el…
Variability in Saturn's bow shock and magnetopause from Pioneer and Voyager: Probabilistic predictions and initial observations by Cassini
Russell, C. T.; Dougherty, M. K.; Neubauer, F. M. +2 more
Probability distributions for the location of the Saturnian bow shock and magnetopause have been derived by extrapolating observations of dynamic solar wind pressures to the position of Saturn's orbit. These observations are those made by the Pioneer 11, Voyager 1 and 2 spacecraft near Saturn's orbit and by the Ulysses spacecraft near its aphelion…
Ion composition variations in the plasma sheet observed by Cluster/RAPID
Zong, Q. -G.; Daly, P. W.; Ruan, P. +5 more
Based on the energetic particle measurements obtained by Cluster/RAPID (Research with Adaptive Particle Imaging Detectors), ion composition variations in the plasma sheet have been investigated. By comparing observations during quiet and storm intervals, it is found that, in addition to the enhanced energy density for all ion species, the ratio of…
Relating near-Earth observations of an interplanetary coronal mass ejection to the conditions at its site of origin in the solar corona
Balogh, A.; van Driel-Gesztelyi, L.; Lucek, E. +7 more
A halo coronal mass ejection (CME) was detected on January 20, 2004. We use solar remote sensing data (SOHO, Culgoora) and near-Earth in situ data (Cluster) to identify the CME source event and show that it was a long duration flare in which a magnetic flux rope was ejected, carrying overlying coronal arcade material along with it. We demonstrate …
Interplanetary shocks unconnected with earthbound coronal mass ejections
Tappin, S. J.; Howard, T. A.
An associated study by Howard and Tappin (2005) identified 7 Earthbound forward shocks (of which 3 were geoeffective) which were not connected with any detectable coronal mass ejection activity along the Sun-Earth line. This largely unexplored result lends evidence to the fact that some large interplanetary transients are not detected by coronagra…
Detecting sub-glacial aquifers in the north polar layered deposits with Mars Express/MARSIS
Gurnett, D. A.; Farrell, W. M.; Plaut, J. J. +1 more
The penetration of the MARSIS radar signal into the polar ice mass is modeled to determine the capability of the instrument to locate sub-glacial aquifers. As a ground penetrating radar, the orbiting MARSIS transmits a signal >1 W between 1-5 MHz. In this work we will investigate the effect of ice reflective and conductive losses on the radar-d…
Drifting field-aligned density structures in the night-side polar cap
Gurnett, D. A.; Persoon, A. M.; Pickett, J. S. +5 more
Spatio-temporal properties of density irregularities in the night-side polar cap are inferred from multi-point observations of auroral hiss at a radial distance of 5 Earth radii. In this case study, we use high resolution data of the wave instruments onboard the four Cluster spacecraft to estimate the local plasma density, obtaining values close t…
Interferometric identification of ion acoustic broadband waves in the auroral region: CLUSTER observations
André, M.; Vaivads, A.; Fazakerley, A. +2 more
We determine the phase velocity and k vector for parallel and oblique broadband extremely low frequency, ELF, waves on nightside auroral magnetic field lines at altitudes around 4.6 RE. We use internal burst mode data from the EFW electric field and wave instrument onboard the Cluster spacecraft to retrieve phase differences between the…
Ion cyclotron waves in the Saturnian magnetosphere associated with Cassini's engine exhaust
Russell, C. T.; Dougherty, M. K.; Khurana, K. K. +3 more
Five hours after the orbit insertion maneuver that placed Cassini into orbit about Saturn, a long (90 minute) burst of ion cyclotron waves were seen, very different than any waves on the inbound leg of the orbit or on succeeding orbits. The ion cyclotron waves were left-hand elliptically polarized and propagating at a moderately large angle to the…