Electric Thrust to GEO

[noeljanes]

Hi everyone!

As part of a University project we need to design a GEO satellite which uses electric propulsion as its main source of thrust. We’re currently trying to do some initial trajectory work to be able to size the motors etc, however I have some questions regarding the best implementation using the python wrapper.

I have managed to get the numerical propagator to work with a continuous thrust maneuver, but this is only providing the final state. Is there anyway of accessing the previous states of the propagation or is it better to run a for loop of discrete propagation steps to achieve this?

Is it potentially desirable to use the DSST propagator instead of a numerical propagator for the transfer to GEO?

Thanks in advance,
Noel

[bcazabonne]

Hi @noeljanes

@noeljanes

I have managed to get the numerical propagator to work with a continuous thrust maneuver, but this is only providing the final state. Is there anyway of accessing the previous states of the propagation or is it better to run a for loop of discrete propagation steps to achieve this?

To access satellite states at different steps between your initial and final states, you have to use a step handler. Two things are needed.
First, you need to create your step handler. To do this you can, for instance, implement the PythonOrekitFixedStepHandler (Python representation of the OrekitFixedStepHandler Java class) that will give you the satellite state at a fixed step during the orbit propagation.
Furthermore, you need to set the orbit propagator in master mode using propagator.setMasterMode(stepSize, YourStepHandler).
Here a Java example that illustrate my explanations. Here a Python example that present an example of PythonOrekitFixedStepHandler class implementation and set the master mode to the propagator.

@noeljanes

Is it potentially desirable to use the DSST propagator instead of a numerical propagator for the transfer to GEO?

It is not desirable to use the DSST propagator with maneuvers. DSST equations are developed using the Method Of Averaging. Therefore, equations are not really adapted for small and random events such as maneuvers. Furthermore, the main advantage of DSST compare to a numerical method is that it can be used with great integration steps (i.e. several hours to several days). Therefore, using maneuvers is again not adapted to DSST because smaller integrations steps must be used.
The only possibility to use maneuvers with DSST is to have very long maneuvers (i.e. several hours).

Best regards,
Bryan