How to quickly place an object in orbit??

[jhglenn]

I'm new to Celestia. Any help is appreciated. I'm trying to find a simple way to place an object like Hubble in orbit around any planet, and then view the object orbiting the planet. Just when I think I'm there, I loose the view of either Hubble or the planet, or both. Can you give me a quick step-by-step of commands to use? Thanks a load.

[selden]

Initially, all you need to do is change

Code: Select all

"Hubble" "Sol/Earth"

to

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"Hubble" "YourStar/YourPlanet"

(Using the actual Star and Planet names, of course)
If it doesn't work, then you need to look very carefully for a typing error.

The second step is to modify the orbital parameters to be correct for your planet's mass and the shape of orbit you want.

[HankR]

Once you've edited the .ssc file as Selden suggested, try this:

Press return to enter type-in selection mode. Type "Hubble", then return. This will select the object (its name will appear at upper left). Then press the 'G' key to go near the object and enter follow mode. It should appear in the center of your view (but may be dark). Press the '}' key (with shift held down) to increase the ambient light, if necessary to see it clearly. Then press the '.' key to zoom out (increase the field of view) until you can see the planet. Once you see it (or if you reach the maximum point of view and still can't see it), use the right mouse button and drag to orbit around the Hubble (which remains in the center of the view) until the planet moves into view behind it. (If you accidentally move the spacecraft out of the view, make sure it's selected and then press 'C' to center it.) To change the relative apparent sizes of the planet and spacecraft, use the 'Home' and 'End' keys to move toward or away from the spacecraft. Then press the ',' key to zoom back in (decrease the field of view) until the Hubble is the size you want. To keep the spacecraft and planet in view as time passes, select the planet by clicking on it (or entering its name) and press the ':' key (with shift) to lock its position relative to the spacecraft. Press the '{' key (with shift) to reduce the ambient light if desired.

Enjoy the view!

- Hank

[guest]

If I might continue the original question........
Suppose ones downloads another model - say the Eagle - and wants to put it orbit around Earth without colliding with all the other satellites; or around Mars, say.......how does a novice do that? I can only copy other parameters - don't know how to create my own from scratch.
Any help hints from you experts? Please?
Thanks,
Ron

[selden]

Ron,

What I usually do is use the ISS orbit and change the parameter "MeanAnomaly" by one degree.
For example, change 13.8216 to 14.8216

This places the new object 1/360 of the orbit away from the ISS, making each invisible from the other.

If you want to change the Radius to something more realistic, you can, but when you're right up next to an object, you really can't tell that it's much bigger than it ought to be.

Alternatively, you can change the MeanAnomaly by a small fraction of a degree so that the satellites are next to one another. Then if you set the Radius correctly you actually can compare their sizes.

Does this help?

[JackHiggins]

Cassini is currently my whipping boy for trying out new models on...

[guest]

Selden,
Thanks for that! It does help. For Mars or somewhere else, I'll just extrapolate, and play around!
Ron