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.

[Bill Harris]

Mike,

This has been a good discussion of the chemistry of Titan's atmosphere. A lot of food for thought.

I'm not a chemist (except for a smattering of geo-chem), but this is my view of Titanian (??) atmospheric chemistry:

The atmosphere is at a higher pressure, and since the gravity of Titan is less, this density varies less with altitude.

The atmospheric temperature of -95*K or so also gives an effectively dense atmosphere with small distances between molecules.

At this low temperature chemcal reactions take a very long time to occur and even intermediate compounds that are unstable under Earthly conditions are stable for subsequent reactions on Titan. We've probably not even thought of the catalysts that can be created.

With no magnetic field of it's own, Titan's atmosphere bears the full brunt of the solar wind, as well as cosmic radiation which add enough energy with that ionizing radiation to initiate some reactions.

Titan's atmosphere is a reaction vessel of, uh titanic proportions, under unearthly conditions.

And at the surface of Titan, with water/ice and methane, nitrogen and ammonia there are undoubtedly clathrates/hydrates under unearthly conditions.

--Bill