[X] My Assistant

[Michael Capobian...]

As we approach Iapetus for this close fly-by, I thought it might be fun to try and predict if, after we see the close up images of the transition region and Voyager Mountains, the source of the dark material will be obviously endogenic or exogenic, or there will still be no obvious explanation.

I'll go for the longshot, endogenic.

Michael

[nprev]

Great question, GS, though I don't think that we know how thick it is (much less its composition and therefore molar mass, assuming it's homogeneous) to figure that out yet. The other big issues associated with this idea are:

1. Why aren't all the icy moons coated in smutz, if Titan is the source? See no obvious reason why this stuff should preferentially migrate outward from Saturn, unless Hyperion's irregular orbit helps to pump it out somehow (and assuming that Hyperion has enough mass to make a difference).

2. What the hell is smutz if it exists, anyhow? Complex, heavy organic molecules presumably do not escape from Titan at any great rate; most effluents must be very light (mostly H2, in fact). Shooting from the hip, here, I'd guess that propane (C3H8) might be close to the upper limit of molecular weight for escaping compounds.

3. Given #2, there must be a significant amount of decomposition of compounds due to solar radiation while they're drifting around in the TST awaiting Iapetus impact, decreasing yield.

4. Once they're on the surface, then additional reactions must be postulated in order to generate the dark material, unless it's just elemental carbon.

Playing devil's advocate here for a theory I personally support...please feel free to kick holes in all this!

[Del Palmer]

1. Why aren't all the icy moons coated in smutz, if Titan is the source?

Perhaps they are, but Enceladus is continuously re-coating them. After all, Enceladus spewings touch at least 11 other moons...