General Question Can I edit the orbits of the planets/moons?

florin_gh

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I am trying to play around with the celestial bodies, for example, bring the Moon closer to the Earth, or even place Earth in orbit around Jupiter. Is that possible? What files do I need to edit?
 

Swigert

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I don't think I know what I am talking about, but perhaps there is data for the celestial body's orbit in the .cfg file. Orbiter\Config\Celestial body\

Don't take this reply too seriously; I don't think I know what I am talking about.
 

Athena

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There's a config file for every celestial body in orbiter that defines its characteristics which can be found in Orbiter\Config, like this for example:

Code:
; === Configuration file for moon Rhea(Saturn) ===
Name = Rhea
Module = Rhea
;EllipticOrbit = TRUE           ; assume unperturbed orbit
;HasElements = TRUE             ; orbital elements follow

; === Planetary Mean Orbits ===
;***cfgBatchDataCalculator
;Epoch =  2005.41409993155
[B][COLOR="Lime"];SemiMajorAxis =  527225476.502165[/COLOR][/B]
;Eccentricity =  9.09561682184622E-04
;Inclination =  .487814614025395
;LongAscNode =  2.94625511954542
;LongPerihelion =  6.30010186733614
;MeanLongitude =  7.83188971564837


; === Physical Parameters ===
Mass = 2.49e21
Size = 7.64e5

; === Rotation and precession parameters ===
; ref: see www.orbiter-forum.com/showthread.php?t=8185
PrecessionLAN = 6.094968867
PrecessionObliquity = 0.4919939866
PrecessionPeriod = -12945.41576
LAN = 5.32513397
LAN_MJD = 51544.5
Obliquity = 0.006183031585
SidRotOffset = 1.22441763
SidRotPeriod = 390312.2289
;SidRotPeriod (days): 4.517502649
;SidRotPeriod (days - node to node): 4.515926777
;Precession Period (years): -35.44261672
;Obliquity (deg): 0.3542616144
;Ecliptic LAN (rad): 6.084331971
;Ecliptic Obliquity (rad): 0.4955736381
;Ecliptic SidRotOffset (rad): 1.095532053
;Axis RMS Error (deg): 1.153824146
;Lat/Lon RMS Error (deg): 0.00772789982

; === Visualisation Parameters ===
AlbedoRGB = 0.24 0.23 0.23       ; by VF2_Rolf

If you want to do a bit of testing with its distance from its parent body, you should change the value of the "SemiMajorAxis".
 

martins

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However, these values will only be used if you uncomment them (remove the leading semicolon), including the "EllipticOrbit" and "HasElements" entries, _and_ if you remove the "Module" entry (modules take preference over explicitly defined elements, if I remember correctly).

2-body orbits only work reasonably if the perturbations really are negligible, otherwise you will see pseudo-force effects when your spacecraft approaches the surface, since the physics of the planet and spacecraft will be incompatible.
 

Sparky

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I know that the rules say no posts past thirty days but they also say to look for things that are relevant to what you want to post. So I'm taking a chance here but it's because it's relevant to what I want to ask.


My question is: if I use using the code to make it more realistic (cause the moon obviously doesn't move that fast) will this effect how it behaves with Earth and the line of noods? if yes can someone with better math skills than me help me out on this cause I want the moon to be at the correct rotation. Thanks
 
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Interstellar Planet

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If I understand correctly, you want to make the moon closer to Earth without changing the orbital period. However, this can't be done using the configuration file. The moon would actually have to move faster if it were closer to the Earth. Orbiter calculates the proper orbital period for all objects and it is not something you could specify in the config file. A different orbital period would not be realistic.
 

Sparky

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If I understand correctly, you want to make the moon closer to Earth without changing the orbital period. However, this can't be done using the configuration file. The moon would actually have to move faster if it were closer to the Earth. Orbiter calculates the proper orbital period for all objects and it is not something you could specify in the config file. A different orbital period would not be realistic.

yeah you miss understood the moon moves to fast in orbiter. What I meant is there is no day and night in a lunar cycle let alone in a human life time. The moon (in real life) moves on it's axis approximately 3 to 3.5 centimeters a year. there are far more lunar cycles around the Earth than there are day and night. The surface of the moon we see today is more or less the same moon our caveman ancestors saw with the naked eye. I want this to happen on orbiter. So can I do this in the config file?
 

boogabooga

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yeah you miss understood the moon moves to fast in orbiter. What I meant is there is no day and night in a lunar cycle let alone in a human life time. The moon (in real life) moves on it's axis approximately 3 to 3.5 centimeters a year. there are far more lunar cycles around the Earth than there are day and night. The surface of the moon we see today is more or less the same moon our caveman ancestors saw with the naked eye. I want this to happen on orbiter. So can I do this in the config file?

I'm not sure what you are trying to say, but you are seriously confused. Orbiter's moon behaves just as in real life. There is most certainly a lunar day/lunar night. The 3.5 cm/year increase in semi-major axis is only significant on a geological timescale and has no bearing on lunar day/night cycles.

Any point on the moon has a daytime lasting bout half of a month and nighttime lasting about half of a month.
 

Sparky

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I looked up the info and it turns out that I was wrong and that NOVA sucks as a show giving misleading scientific info... again (all the more reason to not watch it) Anyway I was incorrect and want to say thank you for letting me know my error. Now I know not to do something stupid with the config file thanks.
 

boogabooga

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I love NOVA.

Out of curiosity, which episode are you referring to?
 
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