Computing Satellite Irradiance at Each Point Along Its Orbit

Orekit Python Wrapper usage
1

Hi,

I would like to compute the irradiance levels at each point along the orbit during propagation. Initially, I assumed that irradiance might be an inherent property of the SpacecraftState class, but it appears that it is not. I couldn’t find it in the API documentation either.

My current approach is to compute it manually by transforming the satellite’s coordinates into a Sun-centered reference frame and applying the irradiance formula for each timestep.

Before starting to do it by myself, I wanted to ask if there is a more precise way to compute this using Orekit. As I said I did not found anything yet.

Thanks in advance!

2

You may want to look at the LightFluxModel and its various implementations that take care of occulting bodies. This is what radiation pressure force models use (together with a model of the satellite that manages absorption/reflection coefficients).

3

I am trying to do it like this:

state = propagator.propagate(sample_date)
irradiance = LightFluxModel.getLightFluxVector(state)

Where state is an instance of the class SpacecraftState.

But I am getting the same error always:

TypeError("descriptor 'getLightFluxVector' for 'LightFluxModel' objects doesn't apply to a 'SpacecraftState' object")

The class LightFluxModel has two functions called getLightFluxVector one that accepts as an input SpacecraftState and the other one that accepts FieldSpacecraftState. Maybe the error is coming from there but I am not sure.

4

Are you using it from Python? Or perhaps are you using an Orekit version before 12.2?

As LightFluxModel is an interface, you have to use one of its implementations, like ConicallyShadowedLightFluxModel or CylindricallyShadowedLightFluxModel.

6

Hi there

It seems like you’re trying to use it like a static method, but it is not. You need to instantiate the LightFluxModel object first, with the cylindrical version for example, and then call it from there.

Cheers,
Romain.

8

So is this the correct way to do it then?

sun = CelestialBodyFactory.getSun()
model = ConicallyShadowedLightFluxModel(Constants.SUN_RADIUS, sun, Constants.WGS84_EARTH_EQUATORIAL_RADIUS)                
irradiance = model.getLightFluxVector(state).getNorm()

And this will give the total irradiance received for that particular state of the satellite?

Thanks in advance