Re: [Orekit Users] removing Droziner and Cunningham attraction models ?

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

paulcefo <paulcefo@buffalo.edu> a écrit :

> Luc,

Hi Paul,

> Will this have an impact on DSST?

Not at all. DSST uses dedicated force models for Earth gravity.
The only force models that are shared between DSST and numerical
propagator are the for non-conservative forces (drag and radiation
pressure), where the DSST adds the Gaussian quadratures on top
of the numerical propagator force models to separate mean motion
and short periods.

For Earth gravity field, we use the DSSTTesseral and DSSTZonal
modules which are separate for Droziner, Cunningham and Holmes-Featherstone.
Here, the reuse is limited the lower level loading of the gravity
field, and in fact DSST loads the unnormalized version of the gravity
field.

best regards,
Luc

> regards,
>
> Paul
>
> --
> Dr. Paul J. Cefola
> Consultant in Aerospace Systems, Spaceflight Mechanics, & Astrodynamics
> Adjunct Faculty, Dept. of Mechanical and Aerospace Engineering,  
> University at Buffalo (SUNY)
>
> 4 Moonstone Way
> Vineyard Haven, MA 02568
> USA
>
> 508-696-1884 (phone on Martha's Vineyard)
> 978-201-1393 (cell)
>
> paulcefo@buffalo.edu
> paul.cefola@gmail.com
>
> On 07/12/2017 11:58 am, MAISONOBE Luc wrote:
> > Hi all,
> >
> > We have had for years three different force models implementations
> > dealing with gravity fields : Droziner, Cunningham and Holmes-Featherstone.
> >
> > The Holmes-Featherstone, introduced in 2013, is by far the most interesting.
> > It has all derivatives implemented analytically, it uses normalized gravity
> > field and it can go beyond degree 69 (in fact up to a few thousands).
> >
> > As our gravity field loading mechanism allows to retrieve both normalized
> > and un-normalized coefficients regardless of what is canonically contained
> > in gravity fields files, it would be really easy for user codes using
> > the older models to switch to the "new" one, while still using the exact
> > same gravity field.
> >
> > I would like to completely remove the older models.
> >
> > Are there any people who would complain about this removal?
> >
> > best regards,
> > Luc