<p>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.</p>
<p>We looked at multiple options like <a href="https://rhodesmill.org/pyephem/" rel="nofollow noreferrer">PyEphem</a> and <a href="https://rhodesmill.org/skyfield/" rel="nofollow noreferrer">SkyField</a>, but they cannot propagate orbits for such long durations. Using TLEs is worse: it works for just a few weeks, not more.</p>
<p>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!</p>

CC BY-SA 4.0
2023-06-16T13:38:45.173Z
A circular orbit is trivial to calculate arbitrarily far into the future.
StephenG - Help Ukraine
CC BY-SA 4.0
2023-06-17T04:21:51.850Z
[Simplified perturbations models](https://en.wikipedia.org/wiki/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
CC BY-SA 4.0
2023-06-17T16:07:00.137Z
@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
CC BY-SA 4.0
2023-06-17T16:08:16.660Z
And this question is for developing a simulator for this proposed space mission: https://www.dakshasat.in/
VBB
CC BY-SA 4.0
2023-06-17T16:10:38.880Z
@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
CC BY-SA 4.0
2023-06-18T08:49:44.360Z
Does this answer your question? [What produces gravitational waves with "periods between about 100 - 8000 seconds"?](https://astronomy.stackexchange.com/questions/30558/what-produces-gravitational-waves-with-periods-between-about-100-8000-seconds)
Starship
CC BY-SA 4.0
2023-06-18T18:06:50.577Z
No, unfortunately it's unrelated.
VBB
CC BY-SA 4.0
2023-07-14T01:25:06.357Z
@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](https://space.stackexchange.com/) 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
CC BY-SA 4.0
2023-07-14T01:25:35.837Z
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
CC BY-SA 4.0
2023-07-14T01:34:21.653Z
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
CC BY-SA 4.0
2023-07-14T01:38:05.263Z
@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](https://astronomy.meta.stackexchange.com/q/560/7982) (homework is covered there) and [Stop the off-hand "this sounds like a homework question" comments that offer no guidance and raise false flags?](https://astronomy.meta.stackexchange.com/q/762/7982)
uhoh
CC BY-SA 4.0
2023-07-14T09:54:57.297Z
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
CC BY-SA 4.0
2023-07-14T19:31:56.417Z
@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
<orbit><artificial-satellite>
How do I calculate the positions of an artificial satellite for a decade?
VBB
# How do I calculate the positions of an artificial satellite for a decade?

(Asked by: username_0 on 2023-06-16)

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](https://rhodesmill.org/pyephem/) and [SkyField](https://rhodesmill.org/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!

**Tags:** orbit, artificial-satellite

> **Comments:**
> **username_1**: A circular orbit is trivial to calculate arbitrarily far into the future.  
> **username_2**: [Simplified perturbations models](https://en.wikipedia.org/wiki/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.  
> **username_0**: @username_3-OnStrike that's a valid point. I'm actually the developer of this tool: http://astrosat-ssc.iucaa.in:8080/ASIMOV/ASIMOV.jsp  
> **username_0**: And this question is for developing a simulator for this proposed space mission: https://www.dakshasat.in/  
> **username_0**: @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.  
> **username_3**: Does this answer your question? [What produces gravitational waves with "periods between about 100 - 8000 seconds"?](https://astronomy.stackexchange.com/questions/30558/what-produces-gravitational-waves-with-periods-between-about-100-8000-seconds)  
> **username_0**: No, unfortunately it's unrelated.  
> **username_4**: @username_0 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](https://space.stackexchange.com/) 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".  
> **username_4**: 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 :-)  
> **username_4**: 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.  
> **username_4**: @username_3-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](https://astronomy.meta.stackexchange.com/q/560/7982) (homework is covered there) and [Stop the off-hand "this sounds like a homework question" comments that offer no guidance and raise false flags?](https://astronomy.meta.stackexchange.com/q/762/7982)  
> **username_0**: Thanks @username_4 - 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!  
> **username_4**: @username_0 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  

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## 0 answers

