Function ground_track 

pub fn ground_track(
    satellite: &Satellite,
    datetimes: &[UtcInstant],
) -> Result<Vec<Wgs84Geodetic>, LookAngleError>

Sub-satellite (ground-track) geodetic points for one already-initialized satellite over a time grid.

For each instant this composes the existing core transforms - propagate to TEME (Satellite::propagate_jd), TEME->GCRS (teme_to_gcrs_compute), GCRS->ITRS/ECEF (gcrs_to_itrs_compute), then ECEF->geodetic (itrs_to_geodetic_compute) - and returns the WGS84 sub-point (geodetic latitude/longitude and ellipsoidal height). No geometry is reinvented; the same TEME->GCRS path look_angle uses feeds an ECEF step and the shared geodetic reduction. Like look_angle_arc, the first propagation or frame error aborts the whole arc.