Why we have to make retrograde orbit for planets closer to kerbol?

[kiwiak]

Why we have to make retrograde orbit for planets closer to kerbol?

And prograde for planets beyond kerbin orbit.

I dont really get it.

[Skorpychan]

Because it saves DeltaV. You're exiting Kerbin the other way, so you're not getting rid of the extra 2.5k you spent getting into orbit.

[Taki117]

We donthis because to drop our solar periapsis we have to slow our orbit, by burning retrograde. the opposite is true for planets further out from Kerbin. there we need to raise our apoapsis by burning prograde relative to our solar orbit (which when you are orbiting Kerbin is the same as kerbins orbit)

[Monkeh]

I am no expert in orbital mechanics, however, keep in mind 'escape velocity', the faster you go, the higher you go, (weirdly the fastest part of an orbit is the closest as well, so that messes with your mind), so if you want to get closer to the sun you have to slow down your orbital velocity so the sun can grab you in it's gravity more effectively and drag you closer.

Think of a boat on the edge of a vortex spinning into the depths, if the boat speeds up, (burns prograde), it may get away and survive. If the boat slows down, (burns retrograde), it will hurtle into the vortex faster.

I understand my very technical language is a huge barrier, but I hope you got the point.

[Tokay Gris]

That's the counterintuitive part of orbital mechanics.

To make an orbit bigger, you need to speed up. To make it smaller, you need to slow down.

The orbits of the inner planets are smaller, so you need to slow down, i.e. burn retrograde (while in Kerbols orbit) or burn retrograde relativ to Kerbins orbit around Kerbol. So you exit Kerbins SOI behind its orbit around Kerbol.

For the outer planets, you need to burn prograde , i.e. speed up your orbit around Kerbol or burn prograd relativ to Kerbins orbit around Kerbol. So you exit Kerbins SOI in front of its orbit around Kerbol.

The resulting orbit is counterclockwise either way. There is no such thing as "retrograde orbit" or "prograde orbit". It is just "smaller orbit" or "bigger orbit".

[Eric S]

Are you talking which way you launch into Kerbin orbit, or which way you leave Kerbin to travel to the planet? All these answers apply to the latter. For the former, you don't actually have to, that was a mistake early on on one explanitory page that never got completely cleaned up. For highest efficiency, you can still launch into a prograde orbit of Kerbin, you just do your ejection burn early on the day side of Kerbin instead of early on the night side.

[DMagic]

You don't have to orbit retrograde (that would mean turning west instead of east during takeoff), you just have to burn retrograde.

A retrograde orbit is easy to get into, either by launching into one, or making the transfer to set it up that way. You end up orbiting the planet/moon in the direction opposite of the direction the planet/moon is orbiting (your orbit is clockwise while the moon is orbiting its host planet counter-clockwise). But that doesn't really have any effect on burning prograde or retrograde to reach a different planet.

[JiWint]

It's like jumping from a car.If you jump from car front,you will be moving forward faster.If you will be jumping away from car back,you will be way slower than the car.

Kinda...