Celestia Forums

I'm trying to be clever and build a double planet system as shown on Grant Hutchison's site http://www.lns.cornell.edu/~seb/celestia/hutchison/invisible-130.html

Though the orbits show up as does the barycenter my worlds don't

here is the code I've been working on and to my eyes it all seems correct, but obviously it isn't


"barycenter" "EPS Ind"
{
Class "invisible"
EllipticalOrbit
{
Period 0.01
SemiMajorAxis 0.0981275
Eccentricity 6.959035E-02
Inclination-5.262652
AscendingNode 38.5663
LongOfPericenter 357.849
MeanLongitude 185.1059
}
RotationPeriod 608.667
Obliquity 0.8478401
RotationOffset 100.781
Albedo 0.0
}

"GHANDI" "EPS Ind/barycenter"
{
Texture "negsoa.jpg"
# Texture "earth8k.dds"
NightTexture "negsoanight.jpg"

# SpecularTexture "earthspec2k.jpg"
Color [ 0.85 0.85 1.0 ]
SpecularColor [ 0.5 0.5 0.55 ]
SpecularPower 25.0
HazeColor [ 1 1 1 ]
HazeDensity 0.3
Radius 6378
# Oblateness 0.003


Atmosphere {
Height 60
Lower [ 0.30 0.52 0.65 ]
Upper [ 0.26 0.47 0.84 ]
Sky [ 0.30 0.48 0.82 ]
CloudHeight 7
CloudSpeed 65
CloudMap "earth-clouds.png"
}

EllipticalOrbit {
Period 20.5
SemiMajorAxis 45000
Eccentricity 0.5
ArgOfPericenter 180
MeanLongitude 90
}
RotationPeriod 23.9344694 # 23.93419
Obliquity -23.45
RotationOffset 280.5 # offset at default epoch J2000

Albedo 0.30
}


"Shiantiag Xing " "EPS Ind/barycenter"
{
Texture "blee2.jpg"
NightTexture "blee2night.jpg"
Mass 1520
Radius 8249


EllipticalOrbit
{
Period 20.5 # Periods must be the same
SemiMajorAxis 360000
Eccentricity 0.5 # Eccentricities must be the same
ArgOfPericenter 0 # Pericenters opposite each other
MeanLongitude 270 # Longitudes opposite each other
}
RotationPeriod 20.65622
Obliquity 0.0
RotationOffset 322.9

Albedo 0.99
}


Here's a pic of what else I've been doing. I made the space habitat myself it Anim8tor....aren't I clever

Give your invisible barycentre a radius larger than either of the orbiting worlds.

Grant

If you mean make the radius say 10000 so it is bigger than either of the planets then its still a no show I'm afraid.

I'm using vir 1.3.0 BTW

Ah-ha.
It's the "Albedo 0.0" statement for the barycentre. It's unnecessary, and it's messing with the rendering of your orbiting planets. Delete that, and it works.
In the world of visible bodies, Celestia doesn't bother rendering moons if the parent body is too dim to see, and be setting an albedo of zero you're activating that routine, I think.

Grant

I would have never thought of that!

Here's the result of your hard work (of course, a bit of tiding up to do!)

That looks like a good system, Guest!

Epsilon Indi.
Ghandi and Shiantiag Xing...
Sounds familiar...

Is that Andrew?

Yep, thats me!

Great stuff this programme isn't it!

BTW does anyone know if there's some kind of limit to the amount of objects you can have in anyone system (apart from draining the memory)

I'm putting a few space habitats and things around my two worlds yet it only seems to work with Ghandi not Shiantiag Xing
here's a pic of what i mean



...see Shiantiag looks so lonely

Yes, it is excellent.

I don't know of any limits, sorry;
can you show us the .ssc to check over?

If you turn on the "console log," Celestia will tell you about many of the errors that it detects in SSC files.

Type a tilde (shift-`) to see the log.

European keyboards (or any keyboard configured for alphabets with diacritical marks) probably need you to type a "space" after the tilde so it can be seen by Celestia.

Well here is where it all starts to go pear shaped. This is the last habitat for Ghandi (which is fine) and the first for Shiantiag Xing (which is not fine)

I can't for the life of me figure out where I've gone wrong ?

"Koena Mitra Rock " "EPS Ind/barycenter/GHANDI"

{

Color [ 0.85 0.85 1.0 ]
Class "spacecraft"
Mesh "kleopatrafac.3ds"
Radius 61.9748
Albedo 4.400954E-02
EllipticalOrbit
{
Epoch 20031111
Period 141.8755
SemiMajorAxis 19020
Eccentricity 0
Inclination 0
AscendingNode 0
ArgOfPericenter 275.8262
MeanAnomaly 0
MeanLongitude 107.1874
}
RotationPeriod 0.053786
}



"Vincent Jiao Orbital" "EPS Ind/barycenter/Shiantiag Xing"

{

Color [ 0.85 0.85 1.0 ]
Class "spacecraft"
Mesh"habitat2.3ds"
Radius 10.94056
Albedo 6.966343E-02
EllipticalOrbit
{
Epoch 20031111
Period 327.9741
SemiMajorAxis 28612.08
Eccentricity 0
Inclination 0
AscendingNode 0
ArgOfPericenter 196.8725
MeanAnomaly 0
MeanLongitude 138.2088
}
RotationPeriod 0.05
Obliquity 0.01

RotationPeriod 1.0e12 #no rotation
Obliquity 1 #match inclination of orbit
Orientation [1 1 1 1] #positions station to rotate around its x-axis
RotationOffset 1 # turns station to face north/south

}


Selden, how do I open the console?

First make sure Celestia's on-screen text display is enabled.
(It's enabled when you can see the name of the selected object in the upper left corner. Type a "v" a few times to see it turn on and off.)

Then type a tilde (~)

The console messages will appear in the lower left corner of Celestia's window in white letters. Arrow keys will scroll through them.

You have two statements for RotationPeriod and Obliquity for your second object definition, which doesn't seem like a showstopper to me, but would be worth correcting to see what happens.

Grant

Ah-ha again.
You have a trailing space in "Shiantiag Xing " in your original planet definition, but not in "EPS Ind/barycenter/Shiantiag Xing" in your satellite definition.
BTW, you don't need a MeanAnomaly and a Mean Longitude statement - one or the other will do.

Grant

Thanks guys for the help! It was that final thing that did it.

I wouldn't have thought one little space could be so important!

Here's the proof of all your problem solving anyway. This is a hollowed out Asteroid caught in the barycenter between Ghandi and Shiantiag Xing, aptly called "Kashmir!"