Estimation and Modeling of Enceladus Plume Jet Density Using Reaction Wheel Control Data

Lee, Allan Y.; Wang, Eric K.; Pilinski, Emily; Macala, Glenn A.; Feldman, Antonette

doi:10.2514/6.2010-7563

Cited by 2 publications

(2 citation statements)

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“…According to our simulations, if plume #4 had a base density comparable to those of plumes #5 and 6 the time interval of the flow deceleration would have been longer than that observed by CAPS. Large variations in neutral gas plume densities associated with different source regions (Alexandria, Cairo and Damascus) have been reported by Lee et al [2010] during the E3 encounter.…”

Section: Discussionmentioning

confidence: 95%

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Flow stagnation at Enceladus: The effects of neutral gas and charged dust

et al. 2012

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[1] Enceladus is one of Saturn's most active moons. It ejects neutral gas and dust particles from its southern plumes with velocities of hundreds of meters per second. The interaction between the ejected material and the corotating plasma in Saturn's magnetosphere leads to flow deceleration in ways that remain to be understood. The most effective mechanism for the interaction between the corotating plasma and the neutral gas is charge exchange which replaces the hotter corotating ions with nearly stationary cold ions that are subsequently accelerated by the motional electric field. Dust particles in the plume can become electrically charged through electron absorption and couple to the plasma through the motional electric field. The objective of this study is to determine the level of flow deceleration associated with each of these processes using Cassini RPWS dust impact rates, Cassini Plasma Spectrometer (CAPS) plasma data, and 3-D electromagnetic hybrid (kinetic ions, fluid electrons) simulations. Hybrid simulations show that the degree of flow deceleration by charged dust varies considerably with the spatial distribution of dust particles. Based on the RPWS observations of dust impacts during the E7 Cassini flyby of Enceladus, we have constructed a dust model consisting of multiple plumes. Using this model in the hybrid simulation shows that when the dust density is high enough for complete absorption of electrons at the point of maximum dust density, the corotating flow is decelerated by only a few km/s. This is not sufficient to account for the CAPS observation of flow stagnation in the interaction region. On the other hand, charge exchange with neutral gas plumes similar to the modeled dust plumes but with base (plume opening) densities of $10 9 cm À3 result in flow deceleration similar to that observed by CAPS. The results indicate that charge exchange with neutral gas is the dominant mechanism for flow deceleration at Enceladus.

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Section: Discussionmentioning

confidence: 95%

“…In addition, allows for a variety of radial profiles for the dust particles through the choice of parameter ‘n’. The use of multiple plumes is well justified by Cassini images of Enceladus' southern polar region [see e.g., Lee et al , 2010, Figure 1].…”

Section: Model Descriptionmentioning

confidence: 99%