Celestia Forums

Hello,
I would like to know if it is possible to have a "massless" object (spacecraft, meteroid, etc.) be gravitationaly affected by a "massive" object (star, planet, etc.) in Celestia.

My main objective is to place many massless objects around the sun and to observe the dynamical outcome of the many small objects. The elements of the massless objects will ideally be readable from a data file that I provide.

I have looked at the MySQL addon and also the Mostly Harmless package but have had no luck in finding or using gravity. I did see some of the screenshot of gravity in MH but it's beyond me at this time to try and duplicate the motion.

Sorry, Celestia does not implement any form of gravity. Objects in Celestia follow predefined paths. Those paths have to be defined including the results of any gravitational effects that are appropriate.

I think the Orbit (Gravity) simulator at
http://www.orbitsimulator.com/ by Tony Dunn would be more appropriate for what you want to do.

PSUPhysicsStudent wrote:Hello,
I would like to know if it is possible to have a "massless" object (spacecraft, meteroid, etc.) be gravitationaly affected by a "massive" object (star, planet, etc.) in Celestia.

My main objective is to place many massless objects around the sun and to observe the dynamical outcome of the many small objects. The elements of the massless objects will ideally be readable from a data file that I provide.

I have looked at the MySQL addon and also the Mostly Harmless package but have had no luck in finding or using gravity. I did see some of the screenshot of gravity in MH but it's beyond me at this time to try and duplicate the motion.

I am sure with "massless" you mean a body that is much lighter than other masses, but certainly NOT really massless...otherwise ...

Of course, Celestia incorporates many subtle effects of gravity, but NOT --for good reasons-- real time gravitational interactions of the observer with other massive bodies.

The essential reasons are that a /correct/ implementation of such gravity effects involving more than two (isolated) masses is VERY hard and too CPU-intensive. Many programs incorporate gravity effects by assuming independent "point sources" of the gravitational field which is getting grossly incorrect in many cases. Just imagine to maneuver with your "spaceship" among the inner moons of Jupiter! Even Jupiters gravitational field alone is very complex due to its /non-spherical/ geometry.

In Celestia we prefer to incorporate only features that are under "theoretical control".

Bye Fridger

Hey, Thanks for your responses. I've been looking at Gravity Simulator for the past few hrs and it may have some use after all. I wish it was a little prettier tho

A few more hrs of "reverse engeneering" of some of the simmulations, I may be able to come up with something.

Is there a more detailed instruction manual that is available for GS? The web help was not very helpful.

Tony visits the Celestia forum once in a while. You might try contacting him directly, by e'mail.

I am working on a more professional grade, high fidelity project if you are willing to wait a few months. My plan is to add an extension class to allow it to output files for visualization in Celestia. So, you'll get the ability to simulate gravity accurately while using the sweet visualization graphics of Celestia.

http://www.celestiaproject.net/forum/viewtopic ... 8&start=30