Re: [Orekit Users] DormandPrince853Integrator integration step

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

Philippe Demoulin <Philippe.Demoulin@aeronomie.be> a écrit :

> Dear all,

Hi Philippe,

> I wonder how to choose the integration steps in DormandPrince853Integrator ?
>
> For example, in the tutorial's DSSTPropagation.java, the  
> Dormand-Prince integrator is build with minStep = 1.e-3 and maxStep  
> = 1.e+3 for the numerical propagator, whereas minStep = 6000 and  
> maxStep = 86400 for the DSST propagator.  Why such a huge difference  
> for minStep ?

The numerical propagator handles the differential equations for osculating
parameters, i.e. parameters including fast dynamics. The DSST on the other
hand separates mean parameters evolutions from short periodics elements
and sums them together at the end (if configured to produce osculating
parameters). The ODE integrator used in DSST therefore only sees mean
parameters which evolves smoothly and at a much lower rate than ocsulating
parameters. It is often the case that step size for mean parameters is
more (and some times much more) than one orbit! These large steps are
the reason why DSST can be used for very fast propagation on very long
term (for example for end of life estimation).

best regards,
Luc

> Thanks in advance for your advice.
>
> Philippe Demoulin