Tweaking the Death Star orbit and other such thoughts

[berg]

So i have successfully placed the Death Star in orbit around earth. Now I want to replicate the orbit it had around the Endor moon in Return of the Jedi. By this I mean that I need it to tidal lock the Deathstar and have it stay centered on one spot on the planet. (it needs to have the shield remember?) maybe to simplify it, i need to tidal lock both? I changed the period of rotation to 1 but when you speed time up, earth always starts to rotate away. any ideas?




i'm running mac os x 10.5 and celestia 1.6

[selden]

Celestia defaults to tidally locked if you omit the rotation period entirely.

[Reiko]

But how would you make it stay stationary over one spot on the planet. I've wondered myself how to place an object at any altitude and have it always remain over the same spot above the planet.

[selden]

The easiest way to place one object in a fixed location relative to another object is to use the FixedPosition directive.
You can specify either xyz coordinates or longitude, latitude and altitude.

Here it is above Hawaii. I used size and altitude info taken from
http://www.theforce.net/swtc/ds/index.html

Code: Select all

"Death Star" "Sol/Earth"
{
        Class "spacecraft"
        Mesh "dstar.3ds"
        Radius 400

   OrbitFrame { BodyFixed { Center "Sol/Earth"}}
   FixedPosition { Planetographic [ -156 21 2000 ]}

   BodyFrame { BodyFixed { Center "Sol/Earth"}}
   FixedRotation {}

   Albedo       0.10
}


[Reiko]

I knew of the xyz option but for some reason they wouldn't stop rotating relative to each other. I never tried the longitude latitude with something up in space, just surface objects.

Thanks!

[selden]

You're very welcome.

[berg]

So right now as i've entered your code, i'm getting the deathstar like inside the atmosphere of earth. I want to put it in an orbit out from earth, yet centered like you have it. any help? I tried to put both the codes together but that didn't work. probably because the Custom orbit overrides the orbit frame right?

[selden]

So right now as i've entered your code, i'm getting the deathstar like inside the atmosphere of earth. I want to put it in an orbit out from earth, yet centered like you have it. any help? I tried to put both the codes together but that didn't work. probably because the Custom orbit overrides the orbit frame right?

That's very strange. Is there any chance you accidentally dropped a 0?
An altitude of 2000 should place its center 2000 km above the surface of the reference object (Earth in this case). That would be well above the Earth's atmosphere.

CustomOrbit is irrelevant: the CustomOrbit specification is valid only for specific planets and moons in our solar system. It's ignored if the specified orbit is not already defined in Celestia's source code.

[selden]

FWIW, here's what it looks like on my system, along with a Cel URL to take you to this viewpoint.
Be sure to do a copy-and-paste of the ssc info that I provided above, into an SSC file that contains nothing else, so that you don't have to worry about having made typos. Also, make sure that the other SSC files defining DeathStars are not in use. Either rename them so that the filetype is not SSC (I usually use .sscNO) or move them out of Celestia's directory tree (e.g. drag them to the desktop).

URL: DeathStar at Earth