[X] My Assistant

[Decepticon]

Here's what extrapolating the current SPICE kernels yields:

IAPETUS 2005 NOV 12 14:34:49 185078153 415,451 km arcmin=12.1
IAPETUS 2006 JAN 25 21:13:08 191495653 873,345 km arcmin=5.7

IAPETUS 2006 APR 11 17:16:28 198047853 602,419 km arcmin=8.3
IAPETUS 2007 SEP 10 12:31:28 242699553 1,259 km arcmin=2186.8

Posted by jmknapp

This time a little further out.

Jan. 2006 - 879,000 km - 5.3 km/pixel - eastern Cassini Region and transition zone, part ofthe "moat" posted by VP


If anyone has made a animation of the encounter please post it!

[elakdawalla]

I listened to a couple of talks at DPS that had bearing on this subject. Here are the notes, from my blog:

Tilmann Denk performed some color mapping of Hyperion and Iapetus. He found interesting patterns of colors on Iapetus' surface. While the dark terrain is generally on Iapetus' leading side, it does also wrap around to trailing side. He found that the leading side dark material is redder than the trailing side, which is relatively greener in color. He suggested that the greenish stuff could be "primordial," endogenous to Iapetus, while the dark red material on the leading side is exogenous. And he wondered out loud whether there may be as many as "three more or less independent processes responsible for the formation of the extreme hemispheric albedo asymmetry on Iapetus?"

John Spencer used CIRS maps to study Iapetus. Because of the dark material and the very long day, Iapetus is "probably warmer than any other surface in the Saturnian system," John said. While Iapetus has a thermal inertia very similar to Phoebe's, the thermal wave from each daytime round of heating penetrates much deeper into Iapetus' skin than it does on Phoebe because of the longer day, 3 centimeters on Iapetus as opposed to 2 millimeters on Phoebe. John covered the usual arguments for why the shape of the albedo dichotomy is strange: "most simple exogenic models [that is, models in which the dark stuff comes from outside Iapetus] darken the leading hemisphere, but Iapetus' bright material extends over the poles, dark stuff extends around the equator [to the trailing side], and pole-facing slopes are bright." So John created a model in which all of Iapetus is covered in a very thin layer of typically dirty ice. The warm days on Iapetus will sublimate some of the ice, which will eventually refreeze -- preferentially so at cooler spots, like the poles. Then, he said, in his model he darkened the leading side symetrically about the apex, which is what you would get from ballistic emplacement of exogenous material. If he runs the model forward in time, "in only about 10,000 years you start to burn off frost on the leading side. In 100 million years you start to burn stuff off on the trailing side. You can actually make this look pretty similar to the current albedo pattern. If you try to do it with a thicker frost it doesn't work."