Single-axis disturbance compensation system
First Claim
1. 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, andthruster 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.
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Abstract
The invention relates generally to an improved system for sensing and compensating for external disturbance forces acting on a satellite while in orbit. A proof mass member is housed within an enclosure and shielded from external, non-gravitational forces. The proof mass is electromagnetically levitated to move in a purely gravitational orbit, along an axis aligned with the satellite'"'"'s velocity vector. The proof mass is subjected to a controlled magnetic biasing field and is caused to have a constant reaction to the resultant biasing force, by means of a thermal control system which maintains constant resistivity of the proof mass, during operation. The position of the proof mass with respect to its axis is detected optically and is utilized to control the firing of spacecraft thrusters. As a result, the satellite is caused to maintain a substantially constant position relative to the proof mass and thereby also is caused to follow a purely gravitational orbit.
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Citations
10 Claims
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1. 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.
Specification