Orbital Mechanics in Structured Vacuum Theory: A Geometric Foundation Without Spacetime Curvature

We present a complete geometric foundation for orbital mechanics based on Structured Vacuum Theory (TVS), where gravitational phenomena emerge from refractive effects in a vacuum with position-dependent density. The theory explains Earth's stable orbit as optical geodesics in variable-density vacuum and derives Mercury's perihelion precession of 42.98'' per century from physical principles without invoking spacetime curvature. The factor 3 in the orbital equation decomposes as 3 = 2 + 1, representing pure refraction and torsional frame-dragging respectively. This framework eliminates singularities, unifies gravity with electromagnetism as torsion in vacuum channels, and provides mechanical explanations for all gravitational phenomena.