4
$\begingroup$

I'm a MSC student in computer science. For my thesis I'm using SGP4 tool to propagate a LEO satellite.

If I have understood rightly, the SPG4 returns the two state vectors r and v in TEME format. (celestrak).

Here my problem: I need to obtain the Keplerian orbital parameter from those two vectors but I have some conversion trouble. I can't figure the difference between TEME and ECI. Are they the same? Can I convert from TEME with this method?

Thanks!

$\endgroup$
2
$\begingroup$

ECI doesn't have an actual reference time, it's just an arbitrary one that is useful. It works well for rockets and things with limited lifespans, but for satellites it is a bit trickier. As Celestrak states:

What is the reference frame of the resulting coordinates? This question is a bit more technical than most we have covered. To be precise, the reference frame of the Earth-centered inertial (ECI) coordinates produced by the SGP4/SDP4 orbital model is true equator, mean equinox (TEME) of epoch.

There is a whole article on how to properly use the coordinates. Using that article, and the question you linked, you should be able to make the conversion you require.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.