Validate frames conversions

[jorgepiloto]

Tries to solve for #22. Although both APIs (orekit and poliastro ones) provide simple routines to convert between fixed and inertial frames for each celestial body, results diverge. I also tried to use Gmat as an extra checker, but output values were also different. Still working on this... :factory:

[jorgepiloto]

Useful resources

• IAU report: https://astropedia.astrogeology.usgs.gov/download/Docs/WGCCRE/WGCCRE2015reprint.pdf
• Orekit implementation IUA poles: https://gitlab.orekit.org/orekit/orekit/-/blob/develop/src/main/java/org/orekit/bodies/PredefinedIAUPoles.java

[astrojuanlu]

I'm back! Let me know if I can help in any way 🚀

[jorgepiloto]

Gmat definitions

• http://gmat.sourceforge.net/docs/R2018a/html/CelestialBody.html#CelestialBody_Remarks

[jorgepiloto]

It seems that Orekit makes use of the IAU WGCCRE 2009 report definitions instead of using IAU WGCCRE 2015 report ones. This introduces numerical differences in Mercury, Mars and Neptune.

[jorgepiloto]

In fact, the IAU report 2015 for the case of Martian planet contains a more detailed numerical description than the one from the IAU report 2009 one...

[jorgepiloto]

Cool, all tests passing finally! 🚀

[jorgepiloto]

Parametrize GMAT scripts using Jinja2: add a template script plus the generator one.

[astrojuanlu]

For the GMAT scripts, @jorgepiloto commented that they're 27 ** 2 😅 so let's use https://jinja.palletsprojects.com/en/2.11.x/ instead, and a small script to generate the scripts from the template.

[jorgepiloto]

Finally, this is ready for review @astrojuanlu 🚀

[jorgepiloto]

All suggested changes have applied @astrojuanlu, except those ones related to the float values within validate_frames.py as this conversion is required when using the Orekit API 👍🏽

[astrojuanlu]

Approved with one minor comment!

[jorgepiloto]

Merged! 😍 Thanks for the deep review @astrojuanlu 🚀