Composition of Titan's ionosphere

T. E. Cravens, I. P. Robertson, Jr H. Waite, Roger Yelle, W. T. Kasprzak, C. N. Keller, S. A. Ledvina, H. B. Niemann, J. G. Luhmann, R. L. McNutt, W. H. Ip, V. De La Haye, I. Mueller-Wodarg, J. E. Wahlund, V. G. Anicich, V. Vuitton

Research output: Contribution to journalArticle

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Abstract

We present Cassini Ion and Neutral Mass Spectrometer (INMS) measurements of ion densities on the nightside of Titan from April 16, 2005, and show that a substantial ionosphere exists on the nightside and that complex ion chemistry is operating there. The total ionospheric densities measured both by the INMS and the Cassini Radio and Plasma Wave (RPWS) experiments on Cassini suggest that precipitation from the magnetosphere into the atmosphere of electrons with energies ranging from 25 eV up to about 2 keV is taking place. The absence of ionospheric composition measurements has been a major obstacle to understanding the ionosphere. Seven "families" of ion species, separated in mass-to-charge ratio by 12 Daltons (i.e., the mass of carbon), were observed and establish the importance of hydrocarbon and nitrile chains in the upper atmosphere. Several of the ion species measured by the INMS were predicted by models (e.g., HCNH+ and C2H5+). But the INMS also saw high densities at mass numbers not predicted by models, including mass 18, which we suggest will be ammonium ions (NH4+) produced by reaction of other ion species with neutral ammonia.

Original languageEnglish (US)
Article numberL07105
JournalGeophysical Research Letters
Volume33
Issue number7
DOIs
StatePublished - Apr 16 2006

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Titan
ionospheres
ionosphere
ion
ions
mass spectrometers
spectrometer
ionospheric composition
radio waves
nitriles
upper atmosphere
plasma waves
magnetospheres
ionospherics
ammonia
magnetosphere
hydrocarbons
ammonium
chemistry
atmospheres

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)

Cite this

Cravens, T. E., Robertson, I. P., Waite, J. H., Yelle, R., Kasprzak, W. T., Keller, C. N., ... Vuitton, V. (2006). Composition of Titan's ionosphere. Geophysical Research Letters, 33(7), [L07105]. https://doi.org/10.1029/2005GL025575

Composition of Titan's ionosphere. / Cravens, T. E.; Robertson, I. P.; Waite, Jr H.; Yelle, Roger; Kasprzak, W. T.; Keller, C. N.; Ledvina, S. A.; Niemann, H. B.; Luhmann, J. G.; McNutt, R. L.; Ip, W. H.; De La Haye, V.; Mueller-Wodarg, I.; Wahlund, J. E.; Anicich, V. G.; Vuitton, V.

In: Geophysical Research Letters, Vol. 33, No. 7, L07105, 16.04.2006.

Research output: Contribution to journalArticle

Cravens, TE, Robertson, IP, Waite, JH, Yelle, R, Kasprzak, WT, Keller, CN, Ledvina, SA, Niemann, HB, Luhmann, JG, McNutt, RL, Ip, WH, De La Haye, V, Mueller-Wodarg, I, Wahlund, JE, Anicich, VG & Vuitton, V 2006, 'Composition of Titan's ionosphere', Geophysical Research Letters, vol. 33, no. 7, L07105. https://doi.org/10.1029/2005GL025575
Cravens TE, Robertson IP, Waite JH, Yelle R, Kasprzak WT, Keller CN et al. Composition of Titan's ionosphere. Geophysical Research Letters. 2006 Apr 16;33(7). L07105. https://doi.org/10.1029/2005GL025575
Cravens, T. E. ; Robertson, I. P. ; Waite, Jr H. ; Yelle, Roger ; Kasprzak, W. T. ; Keller, C. N. ; Ledvina, S. A. ; Niemann, H. B. ; Luhmann, J. G. ; McNutt, R. L. ; Ip, W. H. ; De La Haye, V. ; Mueller-Wodarg, I. ; Wahlund, J. E. ; Anicich, V. G. ; Vuitton, V. / Composition of Titan's ionosphere. In: Geophysical Research Letters. 2006 ; Vol. 33, No. 7.
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