Technical
Keplerian Elements
The six classical orbital elements that uniquely describe a satellite's orbit and its position within it at a given epoch.
Keplerian (orbital) elements parameterise an orbit using six quantities: semi-major axis (size), eccentricity (shape), inclination, right ascension of the ascending node (RAAN), argument of perigee (orientation in the orbital plane), and true anomaly (position along the orbit) at a reference epoch.
Together they let operators predict where a spacecraft will be at any future time, subject to perturbations. They underpin conjunction assessment, manoeuvre planning, and the catalogues that track resident space objects.