Electrical properties of tholins and derived constraints on the Huygens landing site composition at the surface of Titan - Archive ouverte HAL Access content directly
Journal Articles Journal of Geophysical Research. Planets Year : 2018

Electrical properties of tholins and derived constraints on the Huygens landing site composition at the surface of Titan

(1) , (1) , (1) , (2) , (1) , (1) , (1) , (1) , (3) , (4) , (5) , (6)
1
2
3
4
5
6
Anthony Lethuillier
Alice Le Gall
Michel Hamelin
  • Function : Author
  • PersonId : 932681
Francis Schreiber
  • Function : Author
  • PersonId : 1032412
Nathalie Carrasco
Guy Cernogora
  • Function : Author
  • PersonId : 968719
Cyril Szopa
Yann Brouet
  • Function : Author
  • PersonId : 989028

Abstract

In 2005, the complex permittivity of the surface of Saturn's moon Titan was measured by the PWA-MIP/HASI (Permittivity Wave Altimetry-Mutual Impedance Probe/Huygens Atmospheric Structure Instrument) experiment on board the Huygens probe. The analysis of these measurements was recently refined but could not be interpreted in terms of composition due to the lack of knowledge on the low-frequency/low-temperature electrical properties of Titan's organic material, a likely key ingredient of the surface composition. In order to fill that gap, we developed a dedicated measurement bench and investigated the complex permittivity of analogs of Titan's organic aerosols called "tholins". These laboratory measurements, together with those performed in the microwave domain, are then used to derive constraints on the composition of Titan's first meter below the surface based on both the PWA-MIP/HASI and the Cassini Radar observations. Assuming a ternary mixture of water-ice, tholin-like dust and pores (filled or not with liquid methane), we find that at least 10% of water ice and 15% of porosity are required to explain observations. On the other hand, there should be at most 50-60% of organic dust. PWA-MIP/HASI measurements also suggest the presence of a thin conductive superficial layer at the Huygens landing site. Using accurate numerical simulations, we put constraints on the electrical conductivity of this layer as a function of its thickness (e.g., in the range 7-40 nS/m for a 7-mm thick layer). Potential candidates for the composition of this layer are discussed.
Fichier principal
Vignette du fichier
Anthony_Tholins_sans marque.pdf (1.34 Mo) Télécharger le fichier
Origin : Files produced by the author(s)

Dates and versions

insu-01721981 , version 1 (29-06-2018)

Identifiers

Cite

Anthony Lethuillier, Alice Le Gall, Michel Hamelin, Sylvain Caujolle-Bert, Francis Schreiber, et al.. Electrical properties of tholins and derived constraints on the Huygens landing site composition at the surface of Titan. Journal of Geophysical Research. Planets, 2018, 123 (4), pp.807-822. ⟨10.1002/2017JE005416⟩. ⟨insu-01721981⟩
263 View
162 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More