Drag force, setup model

Orekit usage
1

Hi all,
in Orekit is it possible to “update” the Drag force data from a file ?
I mean in GMAT is possible to do that changing the Space weather Setup, also loading different file.

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is it possible to do it also with Orekit ?

Many thanks for your time and help
Best Regards

2

Hi @AlessandroV,

Yes, it is possible. Like GMAT, Orekit can use the CSSI Space Weather data file.

First of all, this file is available in the orekit-data inside /CSSI-Space-Weather-Data folder.
It can be easily updated with latest solar activity data using the update.sh script available with the orekit-data.

Now, please find below an example showing how to initialize an Atmosphere model using these data.

            // Atmosphere model
            CssiSpaceWeatherData cswl = new CssiSpaceWeatherData(nameOfTheFileInOrekitData);
            final Atmosphere atmosphere = new NRLMSISE00(cswl, CelestialBodyFactory.getSun(), centralBody);

After that, you can initialize a DragForce using

ForceModel drag = new DragForce(atmosphere, new IsotropicDrag(crossSection, cd);

Please note that CSSI Space weather data are not the only solar activity provider in Orekit. You also have the MSAFE. Please find below an example of MSAFE initialization.

final MarshallSolarActivityFutureEstimation msafe =
                            new MarshallSolarActivityFutureEstimation(MarshallSolarActivityFutureEstimation.DEFAULT_SUPPORTED_NAMES,
                                                                      MarshallSolarActivityFutureEstimation.StrengthLevel.AVERAGE);
            final Atmosphere atmosphere = new NRLMSISE00(msafe, CelestialBodyFactory.getSun(), centralBody);

MSAFE are monthly updated data while CSSI data are daily updated. Personally, I prefer use the CSSI data :slightly_smiling_face:

Best regards,
Bryan

3

thank you very much
Best Regards
Alessandro