重力傾度による衛星の軌道制御の可能性

抄録

Possibility of orbit control using gravity gradient (GG) effects without any mass expulsion is discussed. For simplicity, a dumb-bell type satellite and circular orbits are mainly considered. It is shown that the GG effects can be applied to convert attitude torques into orbital torques and vice versa. In central gravitational force fields, maximum orbital torques or thrusts are available from the GG force when roll or pitch angle is ±π/4 provided that attitude angle is null when the dumb-bell axis coincides with local vertical. Such external torques as geomagnetic or solar wind pressure can be utilized to maintain the ±π/4 attitude, then orbital torques are availableforever. In non-central gravitational fields, without any external torque, the orbital radii of circular orbits can be increased by controlling the satellite attitude using electric energy. The use of the earth's oblateness effects and the exterior Lunar potential is discussed. Numerical examples are presented.