Single-axis disturbance compensation system

In a system for controlling an artificial earth satellite equipped with thruster means to move at a predetermined velocity along a pure gravitational orbit, the improvement comprising,

• an enclosure attached to the satellite substantially in alignment with the velocity vector of the orbiting satellite,
• an electrically conductive proof mass means disposed within said enclosure and shielded thereby from external non-gravitational forces while said satellite is orbiting,
• said enclosure having interior surfaces disposed symmetrically relative to said proof mass means and forming an equipotential surface to shield said proof mass from electrostatic forces,
• means for generating a controllable eddy current suspension force on said proof mass means to suspend said proof mass means on a reference axis substantially aligned with the velocity vector of the orbiting satellite,
• means for generating a controllable eddy current biasing force on said proof mas means in either direction along said reference axis to position said proof mass means along said axis,
• thermal control means for maintaining a constant temperature within said enclosure to keep constant the electrical resistivity of said proof mass means to eddy currents and thereby also the reaction of said proof mass means to said suspension and biasing forces,
• means for detecting the position of the proof mass means along said axis, and
• thruster control means responsive to said position detecting system for accelerating/decelerating said satellite to maintain a substantially constant position relative to said proof mass means, whereby said satellite also follows a purely gravitational orbit.