Chris Peterson wrote: ↑Mon Jul 04, 2022 1:09 pm
MarkBour wrote: ↑Mon Jul 04, 2022 3:03 am
I wonder, if, as it approaches its Roche limit, will it perhaps begin to rotate?
Why would it? Once it starts to break up the individual pieces will assume their own rotations, with the total angular momentum conserved, of course.
I'm just looking at this image from the Wikipedia "Roche Limit" page and thinking about it intuitively (
As the object approaches the Roche limit, its inner chunks are wanting to orbit angularly more rapidly than the rest, and its outer chunks are wanting to orbit angularly more slowly than the rest. If there is a period of time in which this is appreciable, but during which the body can still "hold it together", then I think it would induce a rotational motion. You might even have some chunks breaking loose, but then rolling along the surface in that direction as well.
My intuition, which is certainly a poor guide here, is that for a fluid satellite, it would not happen. The fluid would just stretch into an ellipsoid and slightly rotate forward, but only less than a single visible rotation of the "body". and then it would begin to disperse (exactly like this image).
But for a rubble pile, I have even more trouble guessing.
I wonder if someone has recorded an experiment that has found a way to show the details at the end before disintegration, or if some numerical simulation has worked it out with satisfactory conclusiveness.
The only example observation I know of is Comet Shoemaker–Levy 9, also discussed in that same Wikipedia article, but not much could be concluded from that example in regard to the fate of Phobos. If someone had a lot of money, they could easily enough set this up orbiting a few small satellites around the Moon. Of course, I doubt anyone is going to do that as a purposeful experiment. But maybe, with lots of varied activity up there, some related observations will be part of life in cislunar space.
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