katateochi

Orbit info on the wiki

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I was looking for some orbital info on the wiki and it seems like some of the information is either wrong or out of date (or I'm being stupid). For example on the page for Mun it lists it's Ap and Pe as 12,000,000 m (12Mm), shouldn't it be 11.4Mm? And Kerbin's Ap & Pe are shown as 13,599,840,256 m, but as far as I can tell it's 13,338,240,256m.

If it is the case that the wiki is out of date then where is the best place to get the accurate orbit info? Oddly enough, I'm not sure how to get really accurate values (down to the meter) out of the game! I can get Ap/Pe values as Mm or Gm to accurate to 3dp using mechjeb, but that's not good enough, hyperedit can give a precise value for "altitude", but that's not enough for non-circular orbits (and HE's value for semi-major axis is I think out of date too, plus I don't know how to use that to calculate Ap and Pe!). 

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Posted (edited)

The orbital informations in the wiki refers to the semi-major axis (SMA), so if you want the orbital altitude (which is displayed in KSP), you have to substract the equatorial radius of the parent.

In case of the Mun:

SMA = 12 000 000m
Equatorial radius of the parent (Kerbin) = 600 000m

Substract the equatorial radius of Kerbin from the SMA of the Mun, and you will get the 11 400 000m you are looking for ;)

It is a bit more complicated for eccentric orbits (if you are looking for Ap/Pe it is just an additional calculation with the semi-minor axis), I would suggest to read through the SMA article of wikipedia.

Edited by 4x4cheesecake
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11 hours ago, 4x4cheesecake said:

The orbital informations in the wiki refers to the semi-major axis (SMA), so if you want the orbital altitude (which is displayed in KSP), you have to substract the equatorial radius of the parent

oh, I see! Thanks for explaining that.

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