Atmospheric Models - Reentry

Orekit Python Wrapper usage
1

Hi!

I’m simulating a reentry with different atmospheric models and I have seen that the reentry time with the SimpleExponentialAtmosphere is about 40 years and with the Harris Priester Model is about 2 years.

I have seen that the density values at each altitude for both models are very similar and I don’t know why this time difference is that big. Is this a normal behaviour, or am I missing something?

The configuration for the SimpleExponentialModel is:

atm = SimpleExponentialAtmosphere(earth, 0.0004, 42000.0, 7500.0)
drag_force = DragForce(atm, isotropic_drag)
propagator.addForceModel(drag_force)

The configuration for the Harris Priester is:

drag_force = DragForce(HarrisPriester(sun, earth), isotropic_drag)
propagator.addForceModel(drag_force)

Many thanks in advance

2

Hi @VeronicaSastre

I don’t think SimpleExponentialAtmosphere is a recommended model. Especially because of its poor accuracy.
For reentry applications, recommended models are NRLMSISE00 and JB2008. If I remember well, for this type of application, NRLMSISE00 is recommended for altitude below 120km and JB2008 for other altitudes.
Just note that the main uncertainty of satellite’s reentry applications is the uncertainty of the solar activity and the modelling of the drag coefficient.

Best regards,
Bryan