Structure of Titan's ionosphere

Model comparisons with Cassini data

I. P. Robertson, T. E. Cravens, J. H. Waite, Roger Yelle, V. Vuitton, A. J. Coates, J. E. Wahlund, K. Ågren, K. Mandt, B. Magee, M. S. Richard, E. Fattig

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

Solar extreme ultraviolet 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. New insights into Titan's ionosphere are being facilitated by data from several instruments onboard the Cassini Orbiter, although the Ion and Neutral Mass Spectrometer (INMS) measurements will be emphasized here. We present dayside ionosphere models and compare the results with both Radio and Plasma Wave-Langmuir Probe (RPWS/LP) and INMS data, exploring the sensitivity of models to ionospheric chemistry schemes and solar flux variations. Modeled electron densities for the dayside leg of T18 and all of T17 (dayside) had reasonable agreement with the measured RPWS electron densities and INMS total ion densities. Magnetospheric inputs make at best minor contributions to the ionosphere for these flybys, at least for altitudes above about 1000 km. At lower (<1100 km) altitudes, the total ion densities measured by the INMS are less than the electron densities measured by the RPWS/LP which could be due to heavy (>100 daltons) ions, which the INMS is not able to detect. Qualitatively, INMS spectra exhibit the same ion species and 12 amu family separations for the dayside ionospheres of T17 and T18 as were seen in the mass spectra measured during T5 (nightside). However, the relative abundance of high-mass (m>50) ion species is about 10 times less for the dayside T17 and T18 passes than it was for the polar nightside T5 flyby, which can perhaps be explained in several ways including differences in neutral composition, less dissociative recombination on the nightside than on the dayside (due to lower electron densities and affecting heavier ion species more than lighter ones), and transport of longer-lived high-mass species from day-to-night.

Original languageEnglish (US)
Pages (from-to)1834-1846
Number of pages13
JournalPlanetary and Space Science
Volume57
Issue number14-15
DOIs
StatePublished - Dec 2009

Fingerprint

Titan
ionospheres
ionosphere
ion
mass spectrometers
ions
spectrometer
electron density
upper atmosphere
solar flux
comparison
radio waves
Saturn
electrostatic probes
plasma waves
plasma
magnetospheres
night
ionospherics
mass spectra

Keywords

  • Atmospheres
  • Chemistry
  • Composition
  • Dayside
  • Ionospheres
  • Titan

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Robertson, I. P., Cravens, T. E., Waite, J. H., Yelle, R., Vuitton, V., Coates, A. J., ... Fattig, E. (2009). Structure of Titan's ionosphere: Model comparisons with Cassini data. Planetary and Space Science, 57(14-15), 1834-1846. https://doi.org/10.1016/j.pss.2009.07.011

Structure of Titan's ionosphere : Model comparisons with Cassini data. / Robertson, I. P.; Cravens, T. E.; Waite, J. H.; Yelle, Roger; Vuitton, V.; Coates, A. J.; Wahlund, J. E.; Ågren, K.; Mandt, K.; Magee, B.; Richard, M. S.; Fattig, E.

In: Planetary and Space Science, Vol. 57, No. 14-15, 12.2009, p. 1834-1846.

Research output: Contribution to journalArticle

Robertson, IP, Cravens, TE, Waite, JH, Yelle, R, Vuitton, V, Coates, AJ, Wahlund, JE, Ågren, K, Mandt, K, Magee, B, Richard, MS & Fattig, E 2009, 'Structure of Titan's ionosphere: Model comparisons with Cassini data', Planetary and Space Science, vol. 57, no. 14-15, pp. 1834-1846. https://doi.org/10.1016/j.pss.2009.07.011
Robertson IP, Cravens TE, Waite JH, Yelle R, Vuitton V, Coates AJ et al. Structure of Titan's ionosphere: Model comparisons with Cassini data. Planetary and Space Science. 2009 Dec;57(14-15):1834-1846. https://doi.org/10.1016/j.pss.2009.07.011
Robertson, I. P. ; Cravens, T. E. ; Waite, J. H. ; Yelle, Roger ; Vuitton, V. ; Coates, A. J. ; Wahlund, J. E. ; Ågren, K. ; Mandt, K. ; Magee, B. ; Richard, M. S. ; Fattig, E. / Structure of Titan's ionosphere : Model comparisons with Cassini data. In: Planetary and Space Science. 2009 ; Vol. 57, No. 14-15. pp. 1834-1846.
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