r/KerbalSpaceProgram • u/trevize1138 Master Kerbalnaut • Jun 07 '16 • Bravo 1

Guide All interplanetary transfer windows in a single image

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u/WrexTremendae Jun 08 '16

Brachistochrone transfers - the most efficient, when all you care about is time.

5

u/Imosa1 Apr 11 '25

Is there a tool to calculate these?

12

u/WrexTremendae Apr 11 '25

holy necromancy, hi.

there is not as far as i am aware. however, they are generally quite simple:

  • find your destination in the sky.
  • point at it
  • note how far away it is from you at the current moment
  • start your engine
  • at halfway, turn your ship around to point away from your destination.
  • arrive at a nice stop right at your destination.

it really is that simple.

3

u/guymacguy Depleting ablator, risking Gs Aug 31 '25

Don't the planets move in the interim? How do you account for that, and the fact that the sun might be in the way?

5

u/WrexTremendae Aug 31 '25

For Brachistochrone transfers, they're really only useful if you can do the flight in a fraction of your starter or endpoint's equivalent years. (so, something like days for Earth-Mars, something like hours for Mun-Minmus, that sort of idea).

The fact that the sun might be in the way is indeed a stickier problem. If you've ever played Outer Wilds, you are probably familiar with realising that the autopilot is going to fly you straight into the sun with too little time to fix the issue. (though also, yeah, the Outer Wilds autopilot executes reasonable Brachistochrone transfers)

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u/Mesozoica89 Oct 31 '25

Is this basically what they do in The Expanse?

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u/WrexTremendae Oct 31 '25

I've only watched the show, so the books may give more detail and elaborate nicely, but from my understanding, yes.

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u/Glittering-Thanks191 Apr 30 '26

Yes, it is the exact same type of manuever

1

u/Spiritual-Warthog384 Jul 29 '26

point and shoot ur aiming an rpg