Gravity Simulator
http://www.orbitsimulator.com/cgi-bin/yabb/YaBB.pl
General >> Discussion >> Create object
http://www.orbitsimulator.com/cgi-bin/yabb/YaBB.pl?num=1134217566

Message started by Roger_Dymock on 12/10/05 at 04:26:06

Title: Create object
Post by Roger_Dymock on 12/10/05 at 04:26:06

When entering orbital elements for, say, an asteroid how do I input the epoch or date for which they are valid ?

Title: Re: Create object
Post by Tony on 12/10/05 at 11:00:08


Roger_Dymock wrote:
When entering orbital elements for, say, an asteroid how do I input the epoch or date for which they are valid ?

You need to make sure that your simulation's date is set for that epoch date.

If you're trying to add the asteroid to an existing simulation where the planets and other solar system objects are accurately positioned, you'll need to run the simulation forwards or backwards to your asteroid's epoch date, pause the simulation, and create or edit the asteroid at that point.  You don't want to take too large of a time step getting to this point, however.  16 would be safe for most circumstances.  If it looks like it might take the computer a few hours to slowly arrive at your desired epoch, use the Autopilot to pause the simulation for you so you don't have to sit next to the computer waiting.  Pause it a few hours early with Autopilot, then when you return to your computer, unpause it, slow your time step and pause it manually at the exact second of your epoch.

If you're not concerned about the accuracy of the other solar system objects, you can simply use menu Time > Set Time to set the date of your asteroid's elements' epoch.

If you need help converting between epoch and calander dates, here's a calculator I created for Orbiter, but it works just fine for Gravity Simulator too:

http://orbitsimulator.com/orbiter/mjdConverter.exe

Title: Re: Create object
Post by Roger_Dymock on 12/11/05 at 09:48:00

Many thanks for that. Is there any way I can modify the orbital elements for an object ?

Title: Re: Create object
Post by Tony on 12/11/05 at 10:58:27


Roger_Dymock wrote:
Many thanks for that. Is there any way I can modify the orbital elements for an object ?

Not directly.  Once an object has been created you can only edit its state vectors.

As a way around this, you can create a new object with the elements you would like, then delete the existing object.

Title: Re: Create object
Post by frankuitaalst on 12/12/05 at 08:40:09

Hallo Tony ,

is there a way to create a new object by just copying the properties of an existing object from the edit menu and changing some values for the new object ?

Kind Regards
Frank

Title: Re: Create object
Post by Tony on 12/12/05 at 09:34:31


frankuitaalst wrote:
Hallo Tony ,

is there a way to create a new object by just copying the properties of an existing object from the edit menu and changing some values for the new object ?

Kind Regards
Frank


In the Create Object window, choose the object you'd like to duplicate as the reference object.  If you leave all the other fields blank, you'll end up with an identically placed object.  Do this while the simulation is paused so that they don't instantly merge into a single object.  Then you can use menu Object > Edit Object to edit your new object's vectors.

In the Create Object window you can give the new object orbital elements if you like, but they'll be based on the reference object, not the Sun.

Gravity Simulator » Powered by YaBB 2.1!
YaBB © 2000-2005. All Rights Reserved.