01:20 <queqiao-> ⟨nvv⟩ Okay I'm a little confused now, I think I'm missing something. What lan should I launch into if I want to get into the iss orbit (around 51 degree inclination) from cape canaveral?

01:21 <queqiao-> ⟨Al₂Me₆⟩ There is no 'the' ISS orbit; all LEO orbits exhibit nodal precession.

01:21 <queqiao-> If you don't have an ISS yet, just launch into an orbit of the right inclination. Otherwise use MJ launch to plane.

01:21 <queqiao-> ⟨Al₂Me₆⟩ * precession (except for a few very specific inclinations).

01:38 <queqiao-> ⟨nvv⟩ ⟪Al₂Me₆⟫ There is no 'the' ISS orbit; all LEO […] ⮪ I know, but I'm just assuming 51 degrees as an example. I'm just trying to do a practical launch, because I can't grasp the concept of LAN

01:40 <queqiao-> ⟨egg⟩ There is a one-parameter family of orbits with a given inclination; the longitude Ω of the ascending node is that parameter. https://upload.wikimedia.org/wikipedia/commons/thumb/e/eb/Orbit1.svg/555px-Orbit1.svg.png

01:41 <queqiao-> ⟨nvv⟩ I've seen it before, I'm just confused by the reference direction

01:42 <queqiao-> ⟨egg⟩ it’s some point on the crystal sphere holding the fixed stars. Its actual location is mostly unimportant.

01:43 <queqiao-> ⟨egg⟩ specifically, it’s the intersection of the 0° and 0 h lines here: https://upload.wikimedia.org/wikipedia/commons/thumb/2/21/Pisces_IAU.svg/596px-Pisces_IAU.svg.png

01:44 <queqiao-> ⟨Al₂Me₆⟩ Oof, Discord is not kind to transparent images.

01:46 <queqiao-> ⟨nvv⟩ Okay I'm a little confused now, I think […] ⮪ but how would I know what lan to launch to if I don't know the reference line? Sorry, I'm not sure how to phrase this.

01:47 <queqiao-> ⟨nvv⟩ Like, wouldn't just measuring from a longitude of 0 (on earth) be easier?

01:48 <queqiao-> ⟨egg⟩ The Earth has an annoying tendency to spin.

01:49 <queqiao-> ⟨egg⟩ While orbits precess, as a first approximation, the orbital plane doesn’t move much on the scale of a day. So if you want to talk about where it is, you need to do that with respect to something that likewise doesn’t move.

01:50 <queqiao-> ⟨egg⟩ (The term _longitude_ of ascending node is not great. This is sometimes called _right ascension_ of ascending node, which is clearer.)

01:57 <queqiao-> ⟨nvv⟩ so do I need to first check where 0 degrees on the celestial coordinates relative to my position?

01:59 <queqiao-> ⟨egg⟩ I still have no idea what you are trying to do, so that doesn’t help with figuring out what you might need to do.

02:10 <queqiao-> ⟨nvv⟩ Basically, how would I know what lan to launch into? Is there some more or less "general" procedure I can do to figure it out?

02:12 <queqiao-> ⟨egg⟩ > how would I know what lan to launch intoFor what purpose? What is it you are trying to achieve?

02:13 <queqiao-> ⟨nvv⟩ Okay I'm a little confused now, I think […] ⮪ For rendezvous. For example in this situation

02:13 <queqiao-> ⟨nvv⟩ * rendezvous or to simply match orbits.

02:13 <queqiao-> ⟨egg⟩ Then you should launch into the orbital plane of the target. So into an orbit which has the same inclination and longitude of the ascending node as your target, as these two parameters define the plane.

02:14 <queqiao-> ⟨egg⟩ * target’s orbit,

02:15 <queqiao-> ⟨egg⟩ Aside: this has nothing to do with Principia, it’s the same in stock; perhaps you’ll find more help in #ro-general or something.

02:15 <queqiao-> ⟨nvv⟩ Ai2Me6 said there's an option for that in mechjeb, but I can't find it

02:15 <queqiao-> ⟨egg⟩ off to #mechjeb-pvg you go, then

02:15 <queqiao-> ⟨nvv⟩ * nvm I'll take this to pvg

02:28 <queqiao-> ⟨nvv⟩ Okay after re reading, I figured it out, thank you so much for being patient with me. Also quick follow up question, if I'm in an orbit that is affected by nodal precession, I'd assume the lan constantly changes by some value, right?

02:29 <queqiao-> ⟨egg⟩ Mostly. You can look at the Principia orbit analyser to see what’s going on.