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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!

VBB
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    A circular orbit is trivial to calculate arbitrarily far into the future. – StephenG - Help Ukraine Jun 16 '23 at 13:38
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    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. – PM 2Ring Jun 17 '23 at 04:21
  • @Starship-OnStrike that's a valid point. I'm actually the developer of this tool: http://astrosat-ssc.iucaa.in:8080/ASIMOV/ASIMOV.jsp – VBB Jun 17 '23 at 16:07
  • And this question is for developing a simulator for this proposed space mission: https://www.dakshasat.in/ – VBB Jun 17 '23 at 16:08
  • @PM2Ring yes that's why we were wondering if there is a tool you can use which incorporates effects as much as possible. Another solution could be to just download actual data for some long-lasting LEO satellite, but they often have orbit corrections, collision avoidance maneuvers etc which make it highly specialised. – VBB Jun 17 '23 at 16:10
  • Does this answer your question? What produces gravitational waves with "periods between about 100 - 8000 seconds"? – Starship - On Strike Jun 18 '23 at 08:49
  • No, unfortunately it's unrelated. – VBB Jun 18 '23 at 18:06
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    @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". – uhoh Jul 14 '23 at 01:25
  • Once it gets there, I'll likely add an answer because I'm pretty sure I know just what you need to do and I can help :-) – uhoh Jul 14 '23 at 01:25
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    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. – uhoh Jul 14 '23 at 01:34
  • @Starship-OnStrike don't speak for others, no "we don't like"'s please. Also, please review the topic of homework questions in meta, rather than issue your own rules. Thanks! See for example Community Policy Repository (homework is covered there) and Stop the off-hand "this sounds like a homework question" comments that offer no guidance and raise false flags? – uhoh Jul 14 '23 at 01:38
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    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! – VBB Jul 14 '23 at 09:54
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    @VBB in this paper they propagate a set of TLEs to make "representative" trajectories that are similar to what the real constellation of satellites would do. In other words, they use Skyfield and its SGP4 to propagate orbits approximately which does take into account precession due to Earth's oblateness and a few other things https://arxiv.org/abs/2211.15908 – uhoh Jul 14 '23 at 19:31

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