Change in Inclination/Orbital Plane Increases Semi-Major Axis? Is This Normal?

5kinflute

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Good morning,

I am simulating an orbit around the lunar / seline celestial body but I ran into a problem where changing inclination / declination massively increases the semi-major axis or apoapsis height even at a slightly small change in inclination / declination angle


I attached an image showing my initial & final orbit of my observation. The satellite is at periapsis with a velocity of 1708 m/s and I applied about 6 N of thrust for a normal + burn to increase declination angle. My goal is to at least have a 45 degree inclination orbit around the moon but this causes my orbit to be more elliptical rather than circular -- and this is a big problem for me now because my altitude is now too high ( I want to maintain at least 100 km altitude )

I decided to jump in Orbiter 2016 and detached from ISS and did a similar burn ( anti-normal - ) and it shows my apoapsis reaching 1.693 M which is a bit a relief for me because I thought I was going crazy... but here I achieved an inclination change all the way down to 139 degrees with unlimited fuel turned on... but in the moon I only got 0.0917 degrees ! if I try to go any HIGHER my orbit becomes hyperbolic!

Is this normal in the moon ? How does other space agencies get around this?

P.S. my source code might have errors which I am still investigating but just wanted to share this post for anyone else having this problem...

UPDATE


After some pondering, walking my dog outside, and tossing / turning in my bed ... the position z vector is actually 0 an orbital plane; non-zero when calculating inclination & declination...it's really all about perspective

[math]\frac{x^{2}}{a^{2}}+\frac{y^2}{b^2}[/math]
 

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n72.75

Move slow and try not to break too much.
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You sure your burning normal+ with respect to your Orbiter around the moon and not the sun or earth? Double check the HUD.
 

5kinflute

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Ah I finally figured out what was going on; I had to ask a dumb question to get there... updated my post..
 

Urwumpe

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Also, you can of course have a change in your apsis nodes while changing your inclination a lot. A 180° change would essentially be about stopping and then accelerating again in the opposite direction...
 
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