Propagation

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Slave mode

The simplest way to propagate is to use the “slave mode”. The final result (at the date of the end of the propagation will be stored in a [PATRIUS] SpacecraftState object.

System.out.println("Initial orbit:");
System.out.println("Date:"+iniOrbit.getDate());
System.out.println("SMA:"+iniOrbit.getA());
 
final SpacecraftState sc = test.propagateInSlaveMode();
 
System.out.println("Final orbit:");
System.out.println("Date:"+sc.getDate());
System.out.println("SMA:"+sc.getA());

Master mode

On the other side, if the user wants to store intermediate data all along the propagation, it is possible to use the “master mode”. To do it, it will have to create an OutputConfig object as below, giving the output frames (inertial and local ones) as well as the output step (here 60s):

final OutputConfig output = new OutputConfig(FramesFactory.getEME2000(), LOFType.LVLH, 60.);

Then, the propagation will be done by calling the propagateInMasterMode method and the list of SpacecraftState (see [PATRIUS] definition) could be recover using the getSpacecraftStateList() method. In the following example, we have no additional events (reason why of the null second argument).

The last argument allows to specify how results will be stored. We may choose between the following options:

• StorageType.MEMORY => only the spacecraft states in memory
• StorageType.FILE_SC_BINARY => only the spacecraft states but directly written in a sqlLite file (to avoid to use too much RAM memory)
• StorageType.FILE_COLUMNS => all output variables (see here) are computed and stored in a sqlLite file.

test.propagateInMasterMode(output, null, StorageType.MEMORY);
List<SpacecraftState> listOfSc = test.getSpacecraftStateList();

The user may now use this list …

final int nb = listOfSc.size();
System.out.println("Amount of S/C states = "+nb);
System.out.println("Final orbit:");
System.out.println("Date:"+listOfSc.get(nb-1).getDate());
System.out.println("SMA:"+listOfSc.get(nb-1).getA());