ISS does not disappear in shadow

[pint]

From the Earth's surface, ISS or other satellites are visible only in a short period of time after sunset but before it enters the shadow of the planet (or of course the opposite is possible: after leaves the shadow but before sunrise).

However, it seems that Celestia always renders ISS as a bright point on the sky, even if it is in the shadow.

Is that a known "missing feature" in Celestia?

[adyga]

you are absolutely right, not only ISS, all of the spaceships that circle arround Earth seem to get sunlight throw Earth !!!
nice bug

[marc]

Have you both got ambient light turned off?

[ElPelado]

doesnt matter the ambient light. its a known problem/bug: the models are always iluminated, doesnt matter where they are. it also happens with the rovers for example: in the night of mars, you can see the bottom of the rover iluminated.

[JackHiggins]

The rovers are actually a slightly different problem- they're "orbiting" an invisible placeholder in the center of the planet, so IF they could be put in shadow, they'd have to be put in shadow by this placeholder, since they're not directly "orbiting" the planet.

When the new way of placing objects on planet surfaces comes out, it might be possible to solve this...

[ElPelado]

they're "orbiting" an invisible placeholder in the center of the planet

can someone explain why we must put an invisible object to put a space craft in the surface? why we cant just put it orbiting mars?
whats the difference?

[JackHiggins]

Here's grant's original post on the topic:

A couple of times recently, people have raised the problem of placing an object at or near the surface of a planet or satellite, and having it stay where it's put, as if it were resting on the surface, or hovering above it.
A synchronous orbit only works at the equator - otherwise the object ends up sliding around in a large figure-of-eight.
So I've produced a workaround that allows you to do this.
1) Create a dummy object that hovers at an appropriate distance from the centre of the parent body, displaced north or south along the rotation axis.
2) Place your object in orbit around this dummy, with an orbital radius that puts it on the planetary surface, and a rotation period that's synchronous with the planet's rotation. If you do this right, you now have your object sitting at the right latitude.
3) Adjust the MeanLongitude of your object's orbit so that it sits at the correct planetary longitude.
4) Tweak your object's Orientation and RotationOffset so that it is correctly orientated relative to the surface of the planet.
5) Admire.

As proof-of-concept, I've placed the 2001 Moonbus model (the only model I've got with landing legs) at the Apollo 17 landing site (the farthest from the Moon's equator). I've annotated the code so that you can see where all the numbers come from. (The hardest bit is adjusting the model orientation - the technique will vary from model to model, depending on how they are originally orientated on the X,Y,Z axes.)
Here's the code:

Code: Select all

#To place a lander on the Moon at 20.18809N, 329.22525W and keep it there

#Desired radius = radius of Moon + desired altitude
#in this case, 1737.54 (lunar radius +10m)

"#" "Sol/Earth/Moon"             #A dummy body to provide a suitable orbit centre
{
        Radius 1
        EllipticalOrbit {
                Period            1e12          #Effectively stationary
                SemiMajorAxis   599.630455      #Desired radius * sin(Latitude)
                AscendingNode    43             #Moon's RotationOffset
                Inclination      90             #Polar orbit
                MeanAnomaly      90             #Fixed on the lunar rotation axis
        }
}
   


"Lander" "Sol/Earth/Moon/#"
{
        Class "spacecraft"
        Mesh "Moonbus.3ds"
        Radius 0.020

        EllipticalOrbit {
                Period            27.321661     #Lunar rotation period

                SemiMajorAxis   1630.793846     #Desired radius * cos(Latitude)

                                                #Moon's RotationOffset =        +43
                MeanLongitude   -286.22525      #Subtract west longitude =     -329.22525
                                                #                               =========
                                                #                              -286.22525
        }

                                        #Latitude in x rotation
        Orientation [20.18809 1 0 0]    #(This parameter will vary depending on the
                                        # orientation of the specific model used)

                                        #Re-orientation of model =      -90
                                        #Moon's RotationOffset =        +43
        RotationOffset -16.22525        #Subtract west longitude =     -329.22525
                                        #                               =========
                                        #                              -376.22525

        Albedo 0.80
}

Because if you just put it orbiting mars directly, unless it was on the equator, it would just go in a figure of 8 loop around the planet, once a day.

Not sure if that actually explains it very well... but that is why you have to use a placeholder!