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Continuing the discussion on this thread:

Movie Interstellar - Question about Escape Velocity

The movie Interstellar shows people on a water planet where time is dilated so much that 1 hour is equal to 7 years back on Earth. Even though they lift off from Earth using a Saturn-V two stage rocket, the leave this water planet in a shuttle craft.

It has been pointed out that the consultant for the movie parked the ring in a stationary orbit 10 AU from a black hole that is 100 million solar masses while the shuttle craft travelled to a planet that was 1 AU from the mass. The shuttle then lifts off from this water planet and returns to the ring. On the planet, time is dilated by 60,000 times.

What velocity would you need to achieve to go from 1 AU in this scenario to 10 AU? Also, by my calculations, the planet is travelling at 99% the speed of light while the ring would be travelling at roughly 1/3 the speed of light. How exactly would you dissipate that much kinetic energy using just chemical engines?

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    $\begingroup$ As already pointed out, Kip Thorne says they don't just use chemical engines, his idea was that they use gravity assists from other smaller black holes orbiting the central supermassive black hole, which can potentially boost the speed of a ship passing close to one by a huge amount. Also, the planet would be traveling closer to 50% the speed of light in the Boyer-Lindquist coordinate system commonly used for Kerr black holes (the same one used to get the 1/3 figure for the larger ship at ~10 AU), where did you get 99% from? $\endgroup$
    – Hypnosifl
    Commented Nov 19, 2014 at 2:06
  • $\begingroup$ Thank you for the correction: 50%. I'm still having trouble with the geometry here. You mention a possible solution is to use an intermediate black hole at a distance of 1.1 AU to slingshot the shuttle in a retrograde direction. How does a black hole (let's assume 4 solar masses) at 1.1 AU not rip this planet out of it's orbit? I'm trying to imagine any mass large enough to provide a relativistic sling shot that still allowed for a stable orbit at 1 AU. $\endgroup$
    – user32023
    Commented Nov 19, 2014 at 2:58
  • $\begingroup$ If you put the IMBH far enough away that it doesn't disturb the orbit of the water planet, then we're back to the original problem: how do you get from the water planet to the IMBH (say at 5 AU to be generous) so you can use it as a slingshot? $\endgroup$
    – user32023
    Commented Nov 19, 2014 at 3:02
  • $\begingroup$ That's a good point about the orbits needing to not be too close or they would tend to have a disruptive gravitational effect, perhaps Thorne didn't consider that issue. As a last resort, one could imagine it was a fluke circumstance that an IMBH that hadn't previously been anywhere near the planet had very recently had its own orbit disrupted to move on a highly eccentric orbit that passed very near the event horizon, so there hadn't been enough time for it to disrupt the planet's orbit significantly. $\endgroup$
    – Hypnosifl
    Commented Nov 19, 2014 at 5:06
  • $\begingroup$ I'm not an expert in planetary mechanics, but an eccentric orbit of an IMBH of several solar masses would just make the system more unstable. Even at 10 AUs, a 4 solar mass BH (the absolute low end for a black hole), would disrupt an orbit of a planet the size of Earth. I can't see a scenario where they could land and climb back out in a matter of hours. $\endgroup$
    – user32023
    Commented Nov 19, 2014 at 13:02

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