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Microwave dielectric constant of liquid hydrocarbons: Application to the depth estimation of Titan's lakes
Author(s) -
Paillou Philippe,
Mitchell Karl,
Wall Stephen,
Ruffié Gilles,
Wood Charles,
Lorenz Ralph,
Stofan Ellen,
Lunine Jonathan,
Lopes Rosaly,
Encrenaz Pierre
Publication year - 2008
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl032515
Subject(s) - titan (rocket family) , radar , impact crater , methane , geology , microwave , dielectric , attenuation , volcano , scattering , remote sensing , environmental science , mineralogy , astrobiology , materials science , optics , physics , seismology , chemistry , aerospace engineering , optoelectronics , quantum mechanics , organic chemistry , engineering
Cassini RADAR reveals the surface of Titan since flyby Ta acquired on October 2004. The RADAR instrument discovered volcanic structures, craters, dunes, channels, lakes and seas. In particular, flyby T16 realized in July 2006 imaged tens of radar‐dark features close to Titan's north pole. They are interpreted as lakes filled with liquid hydrocarbons – mainly methane, a key material in the geologic and climatic history of Titan. In order to perform quantitative analysis and modeling of the radar response of Titan's lakes, the dielectric constant of liquid hydrocarbons is a crucial parameter, in particular to estimate the radar wave attenuation. We present here first measurements of the dielectric constant of LNG (Liquefied Natural Gas), mainly composed of methane, at Ku‐band (10–13 GHz): we obtained a value ɛ = 1.75 – 0.002j. This value is used to model the radar backscattering of lakes observed during T16 flyby. Using a two‐layer scattering model, we derive a relationship that is used to estimate a minimum depth for Titan's lakes. The proposed relationship is also coherent with the observation that the larger and then the deeper lakes are also the darker in radar images.