If I understand correctly, the Penrose process as such (i.e., actually extracting energy from the black hole’s rotation) only works if your exhaust is expelled fast enough, relative to you, that is is put on a negative energy orbit, which necessarily falls into the black hole. I’m not sure how you could perform a retrograde burn in which your exhaust somehow enters the black hole but you don’t, since in a retrograde burn your exhaust is getting extra orbital velocity.
I am still really curious whether it helps to execute the retrograde Oberth maneuver within the ergosphere of a Kerr black hole, and if so whether it is better or worse, or even possible, if you approach on an initially retrograde orbit. Of course the approach orbit is probably steeply inclined because you don’t want to spend any longer than necessary flying at 0.8c through the galactic disc.
Yeah, perhaps one could use the Penrose process in reverse to slow down instead?
If I understand correctly, the Penrose process as such (i.e., actually extracting energy from the black hole’s rotation) only works if your exhaust is expelled fast enough, relative to you, that is is put on a negative energy orbit, which necessarily falls into the black hole. I’m not sure how you could perform a retrograde burn in which your exhaust somehow enters the black hole but you don’t, since in a retrograde burn your exhaust is getting extra orbital velocity.
I am still really curious whether it helps to execute the retrograde Oberth maneuver within the ergosphere of a Kerr black hole, and if so whether it is better or worse, or even possible, if you approach on an initially retrograde orbit. Of course the approach orbit is probably steeply inclined because you don’t want to spend any longer than necessary flying at 0.8c through the galactic disc.