Determining ascending / descending nodes?

[Meithan]

I have a simple question. Suppose I'm orbiting a planet and I want to change my orbital inclination. Is there a way to determine the position of the ascending and descending nodes of my orbit without using mods? I can't target the planet I'm currently orbiting. On Kerbin, I can use the Mun since its orbital plane coincides with Kerbin's equator, but is there another way that works in general?

Edited October 2, 2013 by Meithan

[Geschosskopf]

If you refuse to use mods, then you're stuck with eyeballing it.

Finding the nodes is easy enough. Just put your map view focus on the planet (double-click it) and then move the camera up/down until the planet's orbit appears as a flat horizontal line. Then rotate the view left/right until your orbit crosses the planet's orbit right in the center of the screen. Click there to add a maneuver node to mark the spot (you might not actually use it) and rotate the view vertically so you're looking down from above on your orbit. The maneuver node is at 1 of the ascending/descending nodes and an imaginary vertical line from it through the planet to the other side of your orbit marks the other ascending/descending node. The node you want to use is the one furthest from the planet (less fuel).

Now, using the ascending/descending nodes is a bit tricky if the planet's own orbit is inclined. This is because AFAIK the polar axis of all planets points straight up instead of leaning over like Earth's does. Thus, the planets' equators are usually at slight angles to their orbital paths. Thus, to get a zero inclination orbit relative to the planet, you don't want to quite match its orbital plane. So, you have to go back to the map and move the view so your maneuver node (which is at the ascending or descending node) is in the center of the screen and the planet's equator is horizontal. Then you can tweak the maneuver node until your orbit is parallel with the equator.

[Meithan]

If you refuse to use mods, then you're stuck with eyeballing it.

Oh, I have no problem with using mods, and I'm aware that MechJeb gives this information. My question was more out of interest and to see what clever methods players have devised.

Finding the nodes is easy enough. <snip>

See? This kind of clever method is exactly what I meant! Makes a lot of sense, thanks for the tip.

Now, using the ascending/descending nodes is a bit tricky if the planet's own orbit is inclined. This is because AFAIK the polar axis of all planets points straight up instead of leaning over like Earth's does. Thus, the planets' equators are usually at slight angles to their orbital paths.

But then this would be just like the Earth, whose rotation axis is not perpendicular to the orbital plane. So planets in KSP that have an inclined orbit do have seasons after all (unlike Kerbin).

[Geschosskopf]

Oh, I have no problem with using mods, and I'm aware that MechJeb gives this information. My question was more out of interest and to see what clever methods players have devised.

MJ doesn't make the ascending/descending nodes appear on the map but it does know where they are and will create maneuver nodes at them to change your inclination if you tell it to.

The somewhat irksome thing about this is that KSP definitely knows where ascending/descending nodes are but only draws them when you're doing an intercept instead of always showing them like it does the Pe and Ap.

[Specialist290]

The somewhat irksome thing about this is that KSP definitely knows where ascending/descending nodes are but only draws them when you're doing an intercept instead of always showing them like it does the Pe and Ap.

Agreed. I'd like to see these displayed for the body you're in orbit around whenever you don't have anything targeted, as well as more orbital information in general. Ah well, if wishes were horses...