We are trying to solve what I think should be a simple question: suppose there is a satellite that is launched into a certain orbit, where will it be as a function of time? Let's say we know that it is in a circular orbit with radius R, and the orbital parameters at time T=T0. Now we want to calculate it's position as a function of time for many years - say a decade.

We looked at multiple options like PyEphem and SkyField, but they cannot propagate orbits for such long durations. Using TLEs is worse: it works for just a few weeks, not more.

I understand that there are complex interactions with the atmosphere that are very hard to model and propagate, but we don't care about them. We are okay with any approximations. Any pointers to any codes that do this? We could write our own, but I am hoping solutions exist already!

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    $\begingroup$ A circular orbit is trivial to calculate arbitrarily far into the future. $\endgroup$ Commented Jun 16, 2023 at 13:38
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    $\begingroup$ Simplified perturbations models "predict the effect of perturbations caused by the Earth’s shape, drag, radiation, and gravitation effects from other bodies such as the sun and moon". If you ignore those perturbations your approximation will quickly become useless. $\endgroup$
    – PM 2Ring
    Commented Jun 17, 2023 at 4:21
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    $\begingroup$ @VBB I started writing an answer to this question but then realized that it is asked in Astronomy SE and it would more likely receive an answer in Space Exploration SE There is a question migration process that can happen after a question is closed (which keeps the helpful comments intact) or you could delete this copy and repost it there. Either way, you should take all of the helpful information that you've put in comments and move it back into the original question post so that everyone sees it and doesn't vote to close as "unclear". $\endgroup$
    – uhoh
    Commented Jul 14, 2023 at 1:25
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    $\begingroup$ I’m voting to close this question because the specifics of building an ephemeris for an artificial satellite (accurate drag or not) are not really central to Astronomy Stack Exchange. They are however absolutely central in Space Exploration SE, so hopefully closing will be followed by a swift migration there, at which point 1) hopefully responses in comments will be maintained or moved to the question body, and 2) I and others will likely answers. $\endgroup$
    – uhoh
    Commented Jul 14, 2023 at 1:34
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    $\begingroup$ Thanks @uhoh - I will review similar questions there and post this properly. Meanwhile we've made some progress with skyfield, if we get that working we will share that answer too! $\endgroup$
    – VBB
    Commented Jul 14, 2023 at 9:54


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