Re: [Orekit Users] Problem when doing propagation from different point of views

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

Hi Quentin,

Quentin Nénon <q.nenon@gmail.com> a écrit :

> Hi Orekit users,
>
> First, let me thank Luc very much for the very fast and effective answer he
> gave to my last topic. It is very nice and enjoyable to have support and
> suggestions from the Orekit developer team and users.

Thanks a lot.

> I have another issue I would like to submit to the Orekit users. I am
> trying to use Orekit to propagate  an interplanetary trajectory and in
> order to have the best possible precision, I am creating a manager of
> sphere of influence. The goal is therefore to be able to propagate the
> motion of the spacecraft in different frames (first, in inertial frames).
>
> You will find enclosed a main class that is doing the propagation of the
> same motion but from two different point of views :
>
> -The first one is to consider that the spacecraft is turning around the
> Earth central body and has newtonian perturbations coming from the Sun and
> from the Moon
> -The second one is to consider that the spacecraft is turning around the
> Sun central body and has newtonian perturbations coming from the Earth and
> from the Moon.
>
> I am using the Orekit physical data available on the Orekit website. I have
> Orekit 6.1 and commons math 3.2 as dependances.
>
> At the end of the two propagations, I have a difference in the position of
> about 2800 kilometers, that is not very good ... I verified with my own
> patch that it is not a problem due to the distances between the celestial
> bodies (see the EarthMoonBarycenter topic).
>
> Does anyone has an idea of why I have this result ? Am I doing a mistake
> when I am adding the force models to the propagators ?

I just skimmed over the code and did not see any obvious error.
Could you store not only the final position but a few hundreds  
intermediate points at fixed date (you can use an  
OrekitFixedStepHandler for that) and create a plot showing the error  
evolution throughout the propagation?

I wonder if the problem could not be related to the fact Earth frame  
is not really inertial (due to motion around Sun) and in this case it  
shows up.

best regards,
Luc

> Thanks again,
>
> Quentin



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