Re: [Orekit Developers] Feature #34 (Getting the acceleration computed by a ForceModel)

[MAISONOBE Luc <luc.maisonobe@c-s.fr>]

Tanguy Yannick <Yannick.Tanguy@cnes.fr> a écrit :

> Hello,

Hi Yannick,

> This email follows the discussion about feature #34.
>
> Thanks Luc for your advice.
> In fact, the modifications we made are very closed to what you say  
> (there was a mistake in my previous message on the bug tracker) :
> - the ForceModel interface is modified to provide a new method  
> ("Vector3D computeAcceleration(SpacecraftState s) throws  
> OrekitException;"). All the force models must implement this method,  
> and the "addContribution(...)" method will often use it for its own  
> purpose.

Yes this seems much better. In fact we also need attitude for some  
force models so a SpacecraftState is the simplest object tha t gather  
everything we need.

> - some force models (newtonian attraction, droziner & cunningham,  
> third bodies attraction) provide another method  
> ("computeAcceleration(final PVCoordinates pv, final Frame frame,  
> final AbsoluteDate date)") : this allow easier validation.

Fine.

> - for the other force models (dissipative force models : sun  
> radiation pressure and atmospheric drag), the problem is different  
> because we need to fix some vehicule characteristics (shape, mass).  
> So the modification we made is only used for validation purpose and  
> should stay in a derived class.

I don't understand fully this. Could you explain a little further ?

Nevertheless, I think this feature would be a real improvement to Orekit.

Luc


> Best regards,
>
> Yannick



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