I could implement the MSIS model as well (just found some C code for a NRLMSISE-00 model released in 2002), but I suspect that it may be more computationally expensive and probably overkill for orbiter. And since the accuracy of all these models in orbiter is limited by the fact that I can't really use current observation data for magnetic activity and solar flux, it may not matter very much in the end. Still, if there is demand for MSIS, I could provide it as an option.
Another question: I am currently assuming a constant solar flux value of 140, but maybe I could do at least slightly better than that, and fit a sine to the solar cycle (say between 70 and 250, with an 11-year period). Of course, this would probably diverge into the past and future, beyond the range for which we have measurements, but maybe it would provide a more lively model (in relative terms ) than a constant value.
I hear you. What about this? Shows a Fourier series fit of 4th order (red) to the measured annual flux data (blue stars). I also tried a fit to the log of the flux data (green), which seems to give slightly better results.What about using a FFT on the known activity data and use the first three-four terms for calculating the flux? I would sure like to have a API-Function for solar flux, as it affects also solar sails and solar arrays.
I hear you. What about this? Shows a Fourier series fit of 4th order (red) to the measured annual flux data (blue stars). I also tried a fit to the log of the flux data (green), which seems to give slightly better results.
That is the plan (although the more elegant option would be to equip all those stations with robust orbit boost autopilots that keep them afloat while you are away).