[X] My Assistant

[TritonAntares]

Hi,
let me open this thread on the closest Iapetus flyby on September 10th later this year.
Hopefully we'll get some more clues to solve the mysteries of this odd moon, like the origin of the equatorial ridge and the brightness differance...

First, some new infos given by Tilmann Denk from FU Berlin:
CASSINI will pass Iapetus in roughly 1600 km.
An UVIS star occultation of sigma Sagitarii will now occur about 1 hour before closest approach - instead of during it.
This will now allow an additional window for high resolved pics of the highest known parts of the equatorial ridge at 160°
(phase between ~140° and ~30°) now, apparently a decisive approvement of this encounter.
Detailed planing can be started soon...



Bye.

[tasp]

Regarding the dimensions and 'spin down' of Iapetus, I have noted (although I don't have the precise figures handy) that Iapetus deviates from the expected triaxial ellipsoid shape somewhat.

Could we be seeing the effects of one more factor in generating the observed shape of Iapetus ?? As it spun down and cooled and locked in it's polar flattened shape, would proximity of Iapetus to a secondary orbiting body explain the discrepency ??

If we have a 'squashed' Iapetus, we rightly infer freezing then spin down preserving it's primordial form. If in this era we note a 'deformity' in the form of Iapetus, perhaps we are seeing the signature of a 'submoon' frozen in it's form too.

Not sure how accurately the distortion can be characterized, but with a few assumptions regarding distance to the secondary perhaps we could generate a range of expected masses for it.