Titan's internal structure and the evolutionary consequences.
Planetary and Space Science
10 - 17.
Available under License : See the attached licence file.
Titan’s moment of inertia (MoI), estimated from the quadrupole gravity field measured by the Cassini spacecraft, is 0.342, which has been interpreted as evidence of a partially differentiated internal mass distribution. It is shown here that the observed MoI is equally consistent with a fully differentiated internal structure comprising a shell of water ice overlying a low-density silicate core; depending on the chemistry of Titan’s subsurface ocean, the core radius is between 1980 and 2120 km, and its uncompressed density is 2570–2460 kg m−3, suggestive of a hydrated CI carbonaceous chondrite mineralogy. Both the partially differentiated and fully differentiated hydrated core models constrain the deep interior to be several hundred degrees cooler than previously thought. I propose that Titan has a warm wet core below, or buffered at, the high-pressure dehydration temperature of its hydrous constituents, and that many of the gases evolved by thermochemical and radiogenic processes in the core (such as CH4 and 40Ar, respectively) diffuse into the icy mantle to form clathrate hydrates, which in turn may provide a comparatively impermeable barrier to further diffusion. Hence we should not necessarily expect to see a strong isotopic signature of serpentinization in Titan’s atmosphere.
|Title:||Titan's internal structure and the evolutionary consequences|
|Open access status:||An open access version is available from UCL Discovery|
|Additional information:||This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.|
|Keywords:||Titan, Satellite interiors, Serpentinization|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Earth Sciences|
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