[X] My Assistant

[Decepticon]

Should be a good one. Less than 2 weeks away.

[elakdawalla]

JPL has posted their usual mission description preview PDF (link to the document is in the box at right of that page), and I posted my usual preview, with some additional comments from Amanda Hendrix. JPL's preview is lacking a couple of the tables of information that's usually contained in these things -- a summary of the science plan and a timeline with distances, lat/lon positions, and phase angles, unfortunately.

Although Cassini will be passing close to Mimas and Prometheus, the packed schedule doesn't allow observations of either. And the observations of Calypso will be some time before its closest approach to that moon. On the plus side, in amongst all the optical remote sensing of Hyperion there'll be 2 periods of radio science to pin down its mass.

--Emily

[Gsnorgathon]

... I posted my usual preview, with some additional comments from Amanda Hendrix.  ...

--Emily

So, Hyperion's rotation isn't chaotic, it's meta-chaotic?!

[jmknapp]

So, Hyperion's rotation isn't chaotic, it's meta-chaotic?!

Strictly speaking, wouldn't that be true of Earth and other planets too, which may also have experienced large axis changes over the last billions of years? For example, http://www.gps.caltech.edu/~devans/iitpw/iitpwpr.html

As for astronomical evidence that such a phenomenon can occur, the authors point to Mars. Along the equator of the Red Planet is a gigantic volcanic region known as Tharsis, which is known to be the largest gravity anomaly in the solar system. Tharsis could have formed on the equator, but more likely formed elsewhere on the planet and then migrated to the equator via true polar wander because of rotational torques on its excess mass. Something similar may have happened to Earth, says Kirschvink. At about 550 million years ago, 20 million years before the evolutionary burst, one or more major subduction zones in the ancient oceans closed down during the final stages of assembly of the supercontinent of Gondwanaland, leading to a major reorganization of plate tectonic boundaries.