Atmospheric Chemistry of Titan Options

[Juramike]

Here is a "Benzene-O-Vision" graphic showing the amount of benzene and phenyl radicals at high altitudes on Titan. This is based on detections of benzene and phenyl radical (which recombined in the sample chamber to make benzene) using the INMS instrument during closest approach. The numbers are normalized to constant pressure altitude, roughly 1000 km.



The data was taken from Table 1 in: Vuitton et al, Journal of Geophysical Research 113 (2008) E05007. "Formation and distribution of benzene on Titan". doi: 10.1029/2007JE002997 [EDIT 5/24/10: Article freely available here] and overlaid on a map of Titan.

The authors mentioned that the errors in these measurements are 20%.

These detections are well above the detached haze layer. Most are at the same sun azimuth angle. (T23 observation had the lowest angle.) Assuming that the temporal difference is minimal (each dot is from a different flyby), there doesn't appear to be an obvious correlation with latitude.

This graphic does show that benzene is present even waaaay up in the thermosphere and ionosphere.

[Juramike]

H2 is the key reagent that shunts the pathway to the CH5+ intermediate. Atmospheres with large amounts of H2 will generate CH5+ and thus give low yields of saturated organics, while planetary atmospheres with N2 as the diluant will have a richer organic chemistry via the CH3+ intermediate.



CH5+ (H2 present, boring chemistry): Jupiter, Saturn, Uranus, Neptune
CH3+ (N2 diluant – little H2, exciting chemistry): Titan, Pluto, Triton

Working out the full atmospheric chemistry of Titan will also help understand and be a possible preview for some of the chemistry that could occur on Triton and Pluto. It also provides a more complicated example of the carbon-based chemistry that could be happening on Jupiter and the other gas giants. It will also help shed light on processes that can occur on moons and planets and moons outside our solar system that have methane, and atmospheres with either H2 or N2/Ar.