First results from the Cassini radio occultations of the Titan ionosphere

Kliore, A. J.; Nagy, Andrew F.; Marouf, E. A.; French, R. G.; Flasar, F. M.; Rappaport, N. J.; Anabttawi, Aseel; Asmar, S. W.; Kahann, Daniel S.; Barbinis, E.; Goltz, G.; Fleischman, D.; Rochblatt, D.

doi:10.1029/2007ja012965

Cited by 65 publications

(79 citation statements)

References 40 publications

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“…This shows for the first time an integrated computation from 0 to 1600 km due to three different sources with a coupling through the secondary electron transport. Although this curve cannot be compared in terms of intensity to the nightside measured electron density profiles published in Kliore et al (2008) (because the effective coefficient rate varies with altitude), the global shape can still be compared. At night, the measurements show a layer around about 500 km.…”

Section: Full Height Profile and Comparison With Datamentioning

confidence: 99%

“…The radio experiment onboard Cassini allowed retrieval of the ion densities down to 200 km (Kliore et al 2008). Computing the ion densities from the ion production necessitates a full chemistry code, which is not available in the present work.…”

Section: Full Height Profile and Comparison With Datamentioning

confidence: 99%

“…We study the conditions of the T14 fly-by of Cassini in detail as described in Kliore et al (2008). Because we did not have particle precipitation fluxes, we tried to reproduce them from the data.…”

Section: Reproducing Datamentioning

confidence: 99%

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Ionization processes in the atmosphere of Titan

Gronoff¹,

Lilensten²,

Desorgher

et al. 2009

A&A

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Context. The Cassini probe regularly passes in the vicinity of Titan, revealing new insights into particle precipitation thanks to the electron and proton spectrometer. Moreover, the Huygens probe has revealed an ionized layer at 65 km induced by cosmic rays. The impact of these different particles on the chemistry of Titan is probably very strong. Aims. In this article, we compute the whole ionization in the atmosphere of Titan: from the cosmic rays near the ground to the EUV in the upper atmosphere. The meteoritic layer is not taken into account. Methods. We used the transTitan model to compute the electron and EUV impact, and the planetocosmics code to compute the influence of protons and oxygen ions. We coupled the two models to study the influence of the secondary electrons obtained by planetocosmics through the transTitan code. The resulting model improves the accuracy of the calculation through the transport of electrons in the atmosphere. Results. The whole ionization is computed and studied in details. During the day, the cosmic ray ionization peak is as strong as the UV-EUV one. Electrons and protons are very important depending the precipitation conditions. Protons can create a layer at 500 km, while electrons tend to ionize near 800 km. The oxygen ion impact is near 900 km. The results shows few differences to precedent models for the nightside T5 fly-by of Cassini, and can highlight the sources of the different ion layers detected by radio measurements. Conclusions. The new model successfully computes the ion production in the atmosphere of Titan. For the first time, a full electron and ion profile has been computed from 0 to 1600 km, which compares qualitatively with measurements. This result can be used by chemical models.

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Section: Full Height Profile and Comparison With Datamentioning

confidence: 99%

Section: Full Height Profile and Comparison With Datamentioning

confidence: 99%

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Ionization processes in the atmosphere of Titan

Gronoff¹,

Lilensten²,

Desorgher

et al. 2009

A&A

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“…Atreya 1986; Gan et al 1992;Cravens et al 2008 and references therein) and it has also been suggested as a source of the ionosphere observed by Cassini during T5 (Cravens et al 2006;Agren et al 2007). Cravens et al (2008) also suggested that precipitation of energetic protons and oxygen ions from Saturn's magnetosphere into the atmosphere is an important source at lower altitudes (≈ 500 -800 km) and might explain the ionosphere observed at these altitudes by the Cassini Radio Science (RSS) experiment (Kliore et al 2008).…”

Section: Introductionmentioning

confidence: 99%

“…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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Interferometric meteor head echo observations using the Southern Argentina Agile Meteor Radar

et al. 2014

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A radar meteor echo is the radar scattering signature from the free electrons generated by the entry of extraterrestrial particles into the atmosphere. Three categories of scattering mechanisms exist: specular, nonspecular trails, and head echoes. Generally, there are two types of radars utilized to detect meteors. Traditional VHF all‐sky meteor radars primarily detect the specular trails, while high‐power, large‐aperture (HPLA) radars efficiently detect meteor head echoes and, in some cases, nonspecular trails. The fact that head echo measurements can be performed only with HPLA radars limits these studies in several ways. HPLA radars are sensitive instruments constraining the studies to the lower masses, and these observations cannot be performed continuously because they take place at national observatories with limited allocated observing time. These drawbacks can be addressed by developing head echo observing techniques with modified all‐sky meteor radars. Such systems would also permit simultaneous detection of all different scattering mechanisms using the same instrument, rather than requiring assorted different classes of radars, which can help clarify observed differences between the different methodologies. In this study, we demonstrate that such concurrent observations are now possible, enabled by the enhanced design of the Southern Argentina Agile Meteor Radar (SAAMER). The results presented here are derived from observations performed over a period of 12 days in August 2011 and include meteoroid dynamical parameter distributions, radiants, and estimated masses. Overall, the SAAMER's head echo detections appear to be produced by larger particles than those which have been studied thus far using this technique.

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First results from the Cassini radio occultations of the Titan ionosphere

Cited by 65 publications

References 40 publications

Ionization processes in the atmosphere of Titan

Ionization processes in the atmosphere of Titan

Model-data comparisons for Titan's nightside ionosphere

Interferometric meteor head echo observations using the Southern Argentina Agile Meteor Radar

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