Cassini Magnetometer Observations During Saturn Orbit Insertion

Dougherty, M. K.; Achilleos, N.; André, Nicolas; Arridge, C. S.; Balogh, A.; Bertucci, C.; Burton, M. E.; Cowley, S. W. H.; Erdö́s, G.; Giampieri, G.; Glaßmeier, Karl‐Heinz; Khurana, K. K.; Leisner, J. S.; Neubauer, F. M.; Russell, C. T.; Smith, E. J.; Southwood, D. J.; Tsurutani, B. T.

doi:10.1126/science.1106098

Cited by 216 publications

(243 citation statements)

References 20 publications

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“…Figures 6b-6g show magnetic field data obtained by the Cassini fluxgate magnetometer [Dougherty et al, 2004], specifically three pairs of panels showing residual and filtered data for each of the radial (r), colatitudinal (θ), and azimuthal (φ) spherical polar field components referenced to Saturn's spin and magnetic axis. The upper panel of each pair shows 1 min residual field data with the internal field of the planet subtracted using the "Cassini SOI" model [Dougherty et al, 2005]. The lower panel of each pair shows the filtered residual data, where we have used band-pass filters between periods of 5 and 20 h. It is from the ELS data, in conjunction with the magnetic field data, that we have identified the different plasma regimes.…”

Section: 1002/2015ja021642mentioning

confidence: 99%

Planetary period oscillations in Saturn's magnetosphere: Examining the relationship between abrupt changes in behavior and solar wind‐induced magnetospheric compressions and expansions

et al. 2015

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We examine planetary period oscillations (PPOs) observed in Saturn's magnetospheric magnetic field data from the time of Saturn's equinox in 2009. In particular, we focus on the time period commencing February 2011, when the oscillations started to display sudden and unexpected changes in behavior at ~100–200 day intervals. These were characterized by large simultaneous changes in the amplitude of the northern and southern PPO systems, together with small changes in period and jumps in phase. Nine significant abrupt changes have been observed in the postequinox interval to date, commencing as the Sun started to emerge from a long extended solar minimum. We perform a statistical study to determine whether these modulations in PPO behavior were associated with changes in the solar and/or upstream solar wind conditions. We report that the upstream solar wind conditions show elevated values of solar wind dynamic pressure and density around the time of PPO behavioral transitions, as opposed to before and after these times. We suggest that abrupt changes in PPO behavior may be related to significant changes in the size of the Saturnian magnetosphere in response to varying solar wind conditions.

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Section: 1002/2015ja021642mentioning

confidence: 99%

Planetary period oscillations in Saturn's magnetosphere: Examining the relationship between abrupt changes in behavior and solar wind‐induced magnetospheric compressions and expansions

et al. 2015

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“…In a 4 He magnetometer, a weak electric discharge excites helium atoms to the metastable 2 3 S 1 state, and optical pumping with a 4 He discharge lamp is employed to polarize and detect spin precession of atoms in the metastable state. Such instruments typically have sensitivity on the order of 1 − 10 pT/ √ Hz and have been successfully flown on Ulysses [78] and Cassini [79,80] missions, recently providing new information about magnetospheres of Saturn [81] and its moon Enceladus [82]. Laser-pumped 4 He magnetometers are presently being developed and have demonstrated sensitivity of 200 fT √ Hz [83] while their fundamental sensitivity limit is estimated to be about 5 fT √ Hz [84].…”

Section: Measuring Magnetic Fields In Spacementioning

confidence: 99%

Optical magnetometry

2007

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Some of the most sensitive methods of measuring magnetic fields utilize interactions of resonant light with atomic vapor. Recent developments in this vibrant field are improving magnetometers in many traditional areas such as measurement of geomagnetic anomalies and magnetic fields in space, and are opening the door to new ones, including, dynamical measurements of bio-magnetic fields, detection of nuclear magnetic resonance (NMR), magnetic-resonance imaging (MRI), inertialrotation sensing, magnetic microscopy with cold atoms, and tests of fundamental symmetries of Nature.

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“…A similar body of information is currently being gathered at Saturn by the Cassini orbiter (e.g. Bunce et al, 2005;Dougherty et al, 2005;Gurnett et al, 2005;Young et al, 2005), now also including energetic neutral atom imaging of magnetospheric dynamics (e.g. Krimigis et al, 2005;Paranicas et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Significance of Dungey-cycle flows in Jupiter's and Saturn's magnetospheres, and their identification on closed equatorial field lines

2007

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Abstract. We consider the contribution of the solar winddriven Dungey-cycle to flux transport in Jupiter's and Saturn's magnetospheres, the associated voltages being based on estimates of the magnetopause reconnection rates recently derived from observations of the interplanetary medium in the vicinity of the corresponding planetary orbits. At Jupiter, the reconnection voltages are estimated to be ∼150 kV during several-day weak-field rarefaction regions, increasing to ∼1 MV during few-day strong-field compression regions.The corresponding values at Saturn are ∼25 kV for rarefaction regions, increasing to ∼150 kV for compressions. These values are compared with the voltages associated with the flows driven by planetary rotation. Estimates of the rotational flux transport in the "middle" and "outer" magnetosphere regions are shown to yield voltages of several MV and several hundred kV at Jupiter and Saturn respectively, thus being of the same order as the estimated peak Dungeycycle voltages. We conclude that under such circumstances the Dungey-cycle "return" flow will make a significant contribution to the flux transport in the outer magnetospheric regions. The "return" Dungey-cycle flows are then expected to form layers which are a few planetary radii wide inside the dawn and morning magnetopause. In the absence of significant cross-field plasma diffusion, these layers will be characterized by the presence of hot light ions originating from either the planetary ionosphere or the solar wind, while the inner layers associated with the Vasyliunas-cycle and middle magnetosphere transport will be dominated by hot heavy ions originating from internal moon/ring plasma sources. The temperature of these ions is estimated to be of the order of a few keV at Saturn and a few tens of keV at Jupiter, in both layers.

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Cassini Magnetometer Observations During Saturn Orbit Insertion

Cited by 216 publications

References 20 publications

Planetary period oscillations in Saturn's magnetosphere: Examining the relationship between abrupt changes in behavior and solar wind‐induced magnetospheric compressions and expansions

Planetary period oscillations in Saturn's magnetosphere: Examining the relationship between abrupt changes in behavior and solar wind‐induced magnetospheric compressions and expansions

Optical magnetometry

Significance of Dungey-cycle flows in Jupiter's and Saturn's magnetospheres, and their identification on closed equatorial field lines

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