Osculating Elements

Fundamentals
Title	Osculating Elements
Author(s)	J. Sanz Subirana, JM. Juan Zornoza and M. Hernandez-Pajares, University of Catalunia, Spain.
Level	Medium
Year of Publication	2011

A scheme with the necessary calculations to obtain the osculating orbital elements starting from the position and velocity of the satellite, and vice-versa, is provided as follows (see figure 1):

Calculation of the orbital elements of the satellite from its position and velocity

[math]\displaystyle{ (x, y, z, v_x, v_y, v_z) \Longrightarrow (a, e, i, \Omega, \omega, M) }[/math]

[math]\displaystyle{ \vec c= \vec r \times \vec v \Longrightarrow p=\frac{c^2}{\mu} \Longrightarrow p }[/math]

[math]\displaystyle{ v^2=\mu (2/r -1/a) \Longrightarrow a }[/math]

[math]\displaystyle{ p=a(1-e^2) \Longrightarrow e }[/math]

[math]\displaystyle{ \vec c = c \vec S \Longrightarrow \Omega=\arctan(-c_x/c_y); i=arcs(c_z/c) \Longrightarrow \Omega, i }[/math]

[math]\displaystyle{ \left( \begin{array}{l} x\\ y\\ z \end{array} \right) = R \left( \begin{array}{l} r \cos(V)\\ r \sin(V)\\ 0 \end{array} \right) = r \left( \begin{array}{l} \cos \Omega \cos(\omega+V)- \sin \Omega \sin(\omega+V) \cos i\\ \sin \Omega \cos(\omega+V)+ \cos \Omega \sin(\omega+V) \cos i\\ \sin(\omega+V) \sin i \end{array} \right) \Rightarrow \omega+V }[/math]

[math]\displaystyle{ r=\frac{p}{1+e\cos(V)} \Longrightarrow \omega, V }[/math]

[math]\displaystyle{ \tan(E/2)=(\frac{1-e}{1+e})^{1/2}\tan(V/2) \Longrightarrow E }[/math]

[math]\displaystyle{ M= E -e \sin E \Longrightarrow M }[/math]

Calculation of the position and velocity of the satellite from its orbital elements

where

Figure 1: Orbit in space.