Detection of Titan's Ionosphere from Voyager 1 Radio Occultation Observations

Bird, M. K.; Dutta-Roy, R.; Asmar, S. W.; Rebold, T. A.

doi:10.1006/icar.1997.5831

Cited by 114 publications

(60 citation statements)

References 22 publications

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“…The Voyager 1 fly-by of Titan was able to determine an ionospheric peak of 2400 ± 1100 cm −3 at 1180 ± 150 km (Bird et al 1997), and did not provide any information from below the peak. Therefore, Voyager did not show any evidence for meteoroids effects in its atmosphere.…”

Section: Titanmentioning

confidence: 99%

Meteoric Layers in Planetary Atmospheres

2008

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Metallic ions coming from the ablation of extraterrestrial dust, play a significant role in the distribution of ions in the Earth's ionosphere. Ions of magnesium and iron, and to a lesser extent, sodium, aluminium, calcium and nickel, are a permanent feature of the lower E-region. The presence of interplanetary dust at long distances from the Sun has been confirmed by the measurements obtained by several spacecrafts. As on Earth, the flux of interplanetary meteoroids can affect the ionospheric structure of other planets. The electron density of many planets show multiple narrow layers below the main ionospheric peak which are similar, in magnitude, to the upper ones. These layers could be due to long-lived metallic ions supplied by interplanetary dust and/or their satellites. In the case of Mars, the presence of a non-permanent ionospheric layer at altitudes ranging from 65 to 110 km has been confirmed and the ion Mg + ·CO 2 identified. Here we present a review of the present status of observed low ionospheric layers in Venus, Mars, Jupiter, Saturn and Neptune together with meteoroid based models to explain the observations. Meteoroids could also affect the ionospheric structure of Titan, the largest Saturnian moon, and produce an ionospheric layer at around 700 km that could be investigated by Cassini.

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Section: Titanmentioning

confidence: 99%

Meteoric Layers in Planetary Atmospheres

2008

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“…No intrinsic magnetic field was found at Titan (Ness et al, 1982). Titan was found to have an extensive ionosphere that interacts directly with Saturn's magnetospheric plasma and fields (Hartle et al, 1982;Bird et al, 1997). The interaction leads to Saturn's magnetic field piling up and draping around Titan forming an induced magnetosphere (Ness et al, 1982).…”

Section: Introductionmentioning

confidence: 99%

The orientation of Titan’s dayside ionosphere and its effects on Titan’s plasma interaction

Ledvina

Brecht²,

Cravens

2012

Earth Planet Sp

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A hybrid particle code has been used to examine how Titan's interaction with Saturn's magnetosphere is effected by the orientation of the dayside ionosphere with respect to the incident magnetospheric flow. The hybrid code self-consistently includes a version of Titan's ionosphere represented by 7 generic ion species, over 40 ionneutral chemical reactions, ion-neutral collisions and Hall and Pederson conductivities. Emphasis is placed on what effects the orientation angle has on the ion loss rates, ion densities, and the electric and magnetic fields. The results are analyzed and regardless of the orientation angle the ionosphere is found to be within photochemical equilibrium below 1200 km altitude. The ion loss rates and field structures also show little dependence on the orientation of the dayside ionosphere. It is found to first order illumination angle does not have a significant effect on these features of the Titan interaction.

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“…Solar radiation and energetic plasma from Saturn's magnetosphere ionizes the neutral molecules in Titan's ionosphere, creating an ionosphere at altitudes above about 400 km (Bird et al 1997;Wahlund et al 2005;Young et al 2005;Keller et al 1992;Gan et al 1992;Galand et al 1999;Banaskiewicz et al 2000;Molina-Cuberos et al 2001;Lilensten et al 2005a;Agren et al 2007;Cravens et al 2008, Kliore et al, 2008). Titan's neutral atmosphere consists mainly of molecular nitrogen and methane but the relatively minor amounts of many hydrocarbon and nitrogen-bearing species play an important role in the upper atmosphere and ionosphere Vuitton et al 2006Vuitton et al , 2007Fox and Yelle 1997;Keller et al 1998;Waite et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Model-data comparisons for Titan's nightside ionosphere

Cravens

Robertson

Waite

et al. 2009

Icarus

112

144

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Solar and x-ray radiation and energetic plasma from Saturn's magnetosphere interact with the upper atmosphere producing an ionosphere at Titan. The highly coupled ionosphere and upper atmosphere system mediates the interaction between Titan and the external environment.A model of Titan's nightside ionosphere will be described and the results compared with data from the Ion and Neutral Mass Spectrometer (INMS) and the Langmuir probe (LP) part of the Radio and Plasma Wave (RPWS) experiment for the T5 and T21 nightside encounters of the Cassini Orbiter with Titan.Electron impact ionization associated with the precipitation of magnetospheric electrons into the upper atmosphere is assumed to be the source of the nightside ionosphere, at least for altitudes above 1000 km. Magnetospheric electron fluxes measured by the Cassini electron spectrometer (CAPS ELS) are used as an input for the model. The model is used to interpret the observed composition and structure of the T5 and T21 ionospheres. The densities of many ion species (e.g., CH 5 + and C 2 H 5 + ) measured during T5 exhibit temporal and/or spatial variations apparently associated with variations in the fluxes of energetic electrons that precipitate into the atmosphere from Saturn's magnetosphere.

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Detection of Titan's Ionosphere from Voyager 1 Radio Occultation Observations

Cited by 114 publications

References 22 publications

Meteoric Layers in Planetary Atmospheres

Meteoric Layers in Planetary Atmospheres

The orientation of Titan’s dayside ionosphere and its effects on Titan’s plasma interaction

Model-data comparisons for Titan's nightside ionosphere

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