The Binding Energetics of Methane on Water Ice Surfaces
EMSL Project ID
24814
Abstract
New observations of Saturn's moon Titan by the Cassini-Huygens mission have revealed a world strangely Earth-like in nature. In January 2005, the Huygens probe descended through Titan's atmosphere, returning detailed data on the composition of the atmosphere, and high resolution views of the surface. [1] These images revealed the presence of dark channels cutting into bright terrain, with patterns both dendritic (consistent with rainfall drainage channels) and stubby (consistent with spring-fed channels) in nature. [2] Given Titan's low surface temperature - 94 K - such features could not be formed by liquid water, which persists as a solid bedrock. The atmosphere, though, contains an appreciable amount of methane (1.6% in the stratosphere, increasing to 5% at the surface [3]). Methane can condense in Titan's atmosphere, and would exist as a liquid on its surface. Images taken by the RADAR instrument on Cassini have seen evidence for lakes at the north pole [4], and data from the GCMS instrument on the Huygens probe suggest that the probe landed in a soil saturated in methane [3]. Methane is thus the primary candidate for a working fluid on Titan's surface.If we wish to better understand the "methanological system" on Titan - how methane flows through solid ice or organic soils - it is necessary to understand how methane interacts with these solids. Specifically, we would like to know whether liquid methane will "wet" solid ice or solid organics (if methane will form a contact angle less than 90 degrees at the solid/liquid interface).
We propose to measure the methane/ice and methane/methane binding energies using molecular beam and surface science techniques. Though at temperatures much lower than those encountered on Titan, these data will give us a first clue as to whether methane wets water ice.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2007-05-31
End Date
2008-04-18
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members