Descending Node Normal or Anti-Normal?

[arkie87]

Has anyone else noticed that sometimes when you are passing a descending node, and you want to burn to zero out ascending/descending nodes, you should always have to burn normal, but sometimes, when i try burning normal without using a maneuver node first (because I'm lazy) i find that it is reverse-- i need to burn anti-normal.

What's going on? Is this a glitch with the definition of normal/anti-normal, or is something else happening that I'm not noticing?

Edited December 24, 2014 by arkie87

[Anquietas314]

You burn normal at a descending node in a prograde orbit, and anti-normal in a retrograde one to zero out the inclination difference.

[arkie87]

You burn normal at a descending node in a prograde orbit, and anti-normal in a retrograde one to zero out the inclination difference.

I was just thinking this. I assume by prograde you mean counter-clockwise when viewed from north? This would make sense since normal is defined using the cross product of radial vector and velocity vector

[Anquietas314]

I was just thinking this. I assume by prograde you mean counter-clockwise when viewed from north? This would make sense since normal is defined using the cross product of radial vector and velocity vector

Well, sort of. It should actually be counter-clockwise when viewed from the "normal" direction of the target orbit (which, in the case of a "prograde" orbit, is north or close to it). Prograde really just means "in the same direction as" - in the case of a target orbit, the same direction as the orbit, and in the case of just a "prograde orbit", the same direction as the rotation of the planet/star/... you're orbiting. I should probably have been clearer in my previous post.

[arkie87]

Well, sort of. It should actually be counter-clockwise when viewed from the "normal" direction of the target orbit (which, in the case of a "prograde" orbit, is north or close to it). Prograde really just means "in the same direction as" - in the case of a target orbit, the same direction as the orbit, and in the case of just a "prograde orbit", the same direction as the rotation of the planet/star/... you're orbiting. I should probably have been clearer in my previous post.

Yeah, ive heard people say prograde orbit and the only way to interpret that is in the same direction as the planets rotation. But just thought i'd clarify.

And "normal" direction is defined such that when looking at orbit from normal, orbit is going counter-clockwise always, even in a "retrograde" orbit.

[Anquietas314]

And "normal" direction is defined such that when looking at orbit from normal, orbit is going counter-clockwise always, even in a "retrograde" orbit.

You should read what I said again: I said it (referring to your orbit) should be counter-clockwise when viewed from normal of the target orbit, not yours.

[arkie87]

You should read what I said again: I said it (referring to your orbit) should be counter-clockwise when viewed from normal of the target orbit, not yours.

Oh, my bad sorry!

[Anquietas314]

Oh, my bad sorry!

No problem