Analytical Mechanics of Space Systems, Fourth Edition iterates on an already mature text by expanding some developments and discussions, as well as by including new content from spacecraft dynamics research over the last decade. It provides comprehensive treatment of dynamics of space systems, starting with the fundamentals and covering topics from basic kinematics and dynamics to more advanced celestial mechanics. Taking a tutorial approach, the text guides the reader through the various derivations and proofs to explain the principles underlying the equations at issue, and shows how to apply them to various dynamical systems. Part I covers analytical treatment of basic dynamic principles through advanced energy concepts, including use of rotating reference frames that often occur in aerospace systems. Part II covers basic celestial mechanics, treating the two-body problem, restricted three-body problem, gravity field modelling, perturbation methods, spacecraft formation flying, and orbit transfers. MATLAB, Mathematical, Python, and C-Code toolboxes are provided for rigid body kinematics routines and basic orbital 2-body orbital mechanics routines.