General Question making a custom planet

[Sar]

Hi, I'm trying to create a planet (99942 Apophis) So far what I've managed to do is create a planet with io textures that won't CTD when I look at it. So I don't think I'm in the wrong tracks here, atleast I hope so...

I started with the venus.cfg and this is what I have so far.

; === Configuration file for planet 99942 ===
Name = 99942_Apophis
EllipticOrbit = TRUE ; ignore perturbations
HasElements = TRUE ; orbital elements follow


;ErrorLimit = 1e-5
;SamplingInterval = 211         ; interpolation sampling interval [s]
                                ; (interpolation error ~2m)

; === Physical Parameters ===
Mass = 2.7e10		; DONE
Size = 0.13500e6             ; mean radius
;JCoeff = 0.000027            ; J2 coefficient for gravitational potential
;AlbedoRGB = 2.0 1.8 1.5


; === Planetary Mean Orbits ===
SemiMajorAxis = 137929e6
Eccentricity = 0.191
Inclination = 55.926
LongAscNode = 162.363
LongPerihelion = 55.9075
MeanLongitude = 114.924


; === Rotation Elements ===
SidRotPeriod = 109440


; === Data for the Visual ===
MaxPatchResolution = 8       ; highest sphere patch level

The main problem is this

LongAscNode = 162.363
LongPerihelion = 55.9075
MeanLongitude = 114.924

I have no idea how to figure these out.

Please feel free to correct me anywhere you feel the need to, I'm new to this, so any help is welcome.

As a side note.

;ErrorLimit = 1e-5
;SamplingInterval = 211 

;JCoeff = 0.000027
;AlbedoRGB = 2.0 1.8 1.5

No idea what these mean. Other than that they are commented out.

 

[IgnoreThisBarrel]

You should definitely define [ame="http://en.wikipedia.org/wiki/Albedo"]albedo[/ame], it's how "shiny" and visible an object is.

Also, you'll have to convert those orbital measurements to radians.

I don't know what error limit and sampling interval are though...

 

[orb]

I don't know what error limit and sampling interval are though...

ErrorLimit and SamplingInterval are used if you use a .dll module for that planet(oid). They would be used there for calculations of position and velocity. And the module would be useful, if you want to specify perturbations to your planet's position and velocity.

 

[Wishbone]

Or use Ajaja's spice.dll and the SPICE SPK kernel from data in the NEO/SSD databases at JPL (unfortunately I don't know yet how to get it from SSD, its SPK ID is 2099942)

 

[Sar]

Also, you'll have to convert those orbital measurements to radians.

Okay, so taking that the inclination of apophis is 3.3315 degrees I should write it as 0.05814?

Afaik the formula is radian = degree x (pi / 180) is this correct?

So far everything I've done seems to be in the right direction... Atleast the blob is getting dangerously close in 2029.

 

[IgnoreThisBarrel]

Yep, seems about right. Do you have a mesh for Apophis?

 

[Sar]

Nope, so far I don't even have an idea of what it might look like, I'm just trying to get the orbit to the point where it's somewhat realistic. Then I'll start to think about the mesh if I feel the need to have one. Although if I want to publish this that might be a fun thing to have.

btw. can I define a mesh via .cfg or do I need to make a module for that? I was thinking earlier whether to make a module anyway, but I'm not sure if I really have that much time to commit into this. My understanding of c++ is rather limited, but I have made some ships for my own amusement in the past for orbiter.

 

[IgnoreThisBarrel]

To make said celestiial body use a mesh, make
MaxPatchResolution = 0

 

[tblaxland]

So far everything I've done seems to be in the right direction... Atleast the blob is getting dangerously close in 2029.

I would think that you will want to change EllipticOrbit to FALSE because the pass in 2029 will be greatly effected by Earth. But you need to trade accuracy vs framerate too. In that regard, I recommend Wishbone's solution (ie, using soice.dll).