Re: Tag-team orbits and tidal locking

Logan Kearsley wrote:

> two really big moons in a tag-team orbit... close
> enough that a single body in that position (between
> the upper and lower orbits) would be tide-locked,
> what happens?

Huh. That's a really really good question, especially as it might
apply to the co-orbital moons already known, Epimetheus & Janus.
According to a brief Google, they have synchronous rotations (I assume
with Saturn). Notice that if they have a mutual close encounter every
four years or so, their orbital periods (and therefore rotational
periods if locked) must differ by only about 1 part in 2,100 - it may
simply not be measured to that accuracy. So much for (quick!) empirical
solutions.
In theory, hmm... my first instinct is tidelocked 1:1 as if both
bodies are at the "mean distance". But thinking about it more, it might
be that these two bodies tidelock to *each other*, in the lowest
resonant state that comes closest to a 1:1 average lock with the parent
planet/body as well. What I mean is that the maximum tidal torques
these bodies experience are *not* due Saturn, but due to each other at
closest mutual approach. And tidal torques are STRONGLY dependant on
distance. So one possibility might be a resonant rotation coupling
between them, with a weaker constraint of as close to a 1:1 coupling to
the primary as possible.
The longer answer is to do some actual research... I'll let you know
when I've pulled 4.9 Mb across my little phoneline & digest the result
;-).

--
Brian Davis

.

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