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If planet X exists and is a planetary mass PBH it could unlock the universe in many ways. We could use it as a gravitational slingshot to fire probes at signifi
by api 1y ago
If planet X exists and is a planetary mass PBH it could unlock the universe in many ways. We could use it as a gravitational slingshot to fire probes at significant fractions of the speed of light out for flyby surveys of other solar systems.
- BriggyDwiggs42 1y agoProbably a dumb question but at those energies would we be risking de-orbiting the black hole with such a maneuver?
- adgjlsfhk1 1y agono. if it has the mass of a planet, it has the inertia of a planet
- dtech 1y agoNo, for the same reason slingshotting on a planetary body now has no significant effect on it. The mass difference is too enormous.
- api 1y agoIt’s hard to visualize how weird and extreme black holes are. A black hole with the mass of the Moon would be smaller than a BB but would have the mass and inertia of the Moon. It would be basically immovable as far as we are concerned. Chuck stuff at it all day and its trajectory change would be so small we probably wouldn’t be able to measure it.
- BriggyDwiggs42 1y agoThat makes sense, thanks!
- dwaltrip 1y agoIt would make a better slingshot than a planet of the same mass?
- adgjlsfhk1 1y agoyes. you can get a lot closer to it.
- positron26 1y agoAnd you can pick how strong you want the gravity to be up to the event horizon
- perihelions 1y agoWhat's a plausible mechanism for that? There's no net change in speed in a two-body interaction. The conventional slingshot mechanism is a three-body interaction that involves a massive planet's rotation around the sun, but that's a very low speed for Planet 9—much slower than i.e. Jupiter.
- api 1y agoOberth effect is one: https://en.m.wikipedia.org/wiki/Oberth_effect https://en.m.wikipedia.org/wiki/Oberth_effect Fire a super high thrust engine during flyby. If the PBH were in orbit around the Sun I don’t see why a conventional gravity assist would not work, but an Oberth effect maneuver would be more powerful.
- perihelions 1y agoWhen you have a conventional gravity assist, the speed (magnitude) is unchanged in the coordinate frame of the planet that's providing the assist. All that happens is the velocity vector is rotated in that frame. Thus the usefulness hinges on arriving with a large relative velocity, to start with—a large vector to rotate, allows for a large velocity change. There's no heliocentric velocity in a slow-moving outer planet.