Which way takes less fuel?

[WobblyRocketsAreAnnoying]

When entering Duna's (or any other planet) SOI, should I plan to do my capture burn on the bright side of the planet or the dark side? I think one of them is more efficient but I forgot which one.

[Socraticat]

It's not about which side, it's about which direction.

If you go against the celestial's rotation it's more expensive to land and take off since you are also adding the celestial's rotational velocity at the surface to your maneuver cost.

It is so much better to land, dock, or do anything else on the bright side of a planet though, so it's nice to keep both the celestial's rotation and bright side in mind when planning.

 

[WobblyRocketsAreAnnoying]

Thanks for the help!

[RevanX_LSR]

the bright side is usually the way that takes less fuel if you do a normal transfer.