The electrical properties of Titan’s surface at the Huygens landing site measured with the PWA-HASI Mutual Impedance Probe. New approach and new findings

Michel Hamelin (1) , Anthony Lethuillier (1) , Alice Le Gall (1) , Réjean Grard (2) , Christian Béghin (3) , Konrad Schwingenschuh (4) , Irmgard Jernej (4) , José-Juan López-Moreno (5) , Vic Brown (5) , Ralph D. Lorenz (6) , Francesca Ferri (7) , Valérie Ciarletti (1)

1 PLANETO - LATMOS
2 RSSD - Research and Scientific Support Department, ESTEC
3 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
4 IWF - Space Research Institute of Austrian Academy of Sciences
5 IAA - Instituto de Astrofísica de Andalucía
6 APL - Johns Hopkins University Applied Physics Laboratory [Laurel, MD]
7 CISAS - Centro di Ateneo di Studi e Attività Spaziali “Giuseppe Colombo”

Ten years after the successful landing of the Huygens Probe on the surface of Titan, we reassess the derivation of ground complex permittivity using the PWA-MIP/HASI measurements (Permittivity, Waves and Altimetry-Mutual Impedance Probe/Huygens Atmospheric Structure Instrument) at the frequencies 45, 90 and 360 Hz. For this purpose, we have developed a numerical method, namely “the capacity-influence matrix method”, able to account for new insights on the Huygens probe attitude at its final resting position. We find that the surface of Titan at the landing site has a dielectric constant of 2.5±0.3 and a conductivity of 1.2±0.6 nS/m, in agreement with previously published results but with much more reliable error estimates. These values speak in favour of a photochemical origin of the material in the first meter of the subsurface. We also propose, for the first time, a plausible explanation for the sudden change observed by PWA-MIP ∼11 min after landing: this change corresponds to a drop in the ground conductivity, probably due to the removal of a superficial conductive layer in association with the release of volatile materials warmed by the Huygens Probe.

Mots clés: Titan; Titan surface; Satellite surfaces; Data reduction techniques

Domaines: Planétologie et astrophysique de la terre [astro-ph.EP]; Instrumentation et méthodes pour l'astrophysique [astro-ph.IM]; Astrophysique stellaire et solaire [astro-ph.SR]; Electromagnétisme

Michel Hamelin, Anthony Lethuillier, Alice Le Gall, Réjean Grard, Christian Béghin, et al.. The electrical properties of Titan’s surface at the Huygens landing site measured with the PWA-HASI Mutual Impedance Probe. New approach and new findings. Icarus, 2016, 270, pp.272-290. ⟨10.1016/j.icarus.2015.11.035⟩. ⟨insu-01244880⟩