Ice – Hydrocarbon Interactions under Titan-like Conditions: Implications for the Carbon Cycle on Titan

Introduction: The Cassini spacecraft has been orbiting in the Saturn system since July 2004. Remote sensing instruments have discovered dunes, river beds, lakes, seas, impact craters, mountains and cryovolcanic features [e.g. 1 7]. Titan’s activity is somehow similar to that of Earth with methane and ethane playing the role of water and ice that of silicates. In Titan’s surface condition (P=1.5 bar, T=92-94 K), methane and ethane are in the liquid phase (Fig. 1). In addition, the Visual and Infrared Mapping Spectrometer (VIMS) acquired infrared spectra of Ontario Lacus, located in the south pole area, which are best explained if the lake is composed of a mixture of liquid ethane and methane [8]. As it is the case for water on Earth, the partial pressure of methane in Titan’s atmosphere is too low for it to remain in the liquid phase. The Cassini data raise several question that require laboratory experiments: • How hydrocarbons flow on and within an icy crust? • Do hydrocarbons react with ice and what compounds are formed? • What is the composition of Titan’s surface that can match the infrared spectra? These questions have led us to set up a Titan chamber where we can study the interaction between hydrocarbons and an icy substrate.