Best return trajectory from the Mun

[Nibb31]

One thing I have trouble with is getting an optimized trajectory to return from the Munar. Basically, what I want is to burn from Munar orbit so that when I enter Kernin\'s SOI, my Periapsis reenters Kerbin or at least put\'s me in something like a 200km orbit.

I\'ve tried firing from above the Mun\'s prograde point (there must be a term in orbital physics for that) or at the point where Kerbin rises over the horizon or straight to Kerbin. I\'ve tried burning into high or low Munar orbits. Most of the time I end up in something like a 2Mx8M orbit, which requires a costly burn to lower the periapsis for reentry.

There must be a better way!

[Kosmo-not]

It should look something like in this video:

KSP tutorial: Mission to the Mun and Back

[The_Duck]

You want to burn directly opposite the Mun\'s velocity. The correct way to think about the situation is that by being on the Mun you are in orbit around Kerbin, and you need to perform a deorbit burn like you would from any other orbit. The Mun\'s orbital velocity is around 550 m/s so you might think you should burn till you reach about that speed relative to the Mun, but in fact the Mun will slow you down some, so you need to start out faster. I usually burn till I reach 850 m/s directed opposite the Mun\'s orbital velocity. The correct speed may vary depending what altitude munar orbit you start from; I usually skip entering munar orbit and start the TKI burn directly from the munar surface.

[Trekkin]

I usually skip entering munar orbit and start the TKI burn directly from the munar surface.

I do this as well, and make up for the increased fuel cost by deorbiting Kerbin via aerobraking.

[Kosmo-not]

I do this as well, and make up for the increased fuel cost by deorbiting Kerbin via aerobraking.

You don\'t need to aerobrake. A PE of 30km will bring you down with a 2G descent.