Gravity-gradient stabilization

<p>Gravity-gradient stabilization or tidal stabilization is a passive method of <a href="/facts/Spacecraft_attitude_control/hE6aMu26">stabilizing</a> <a href="/facts/Artificial_satellite/PTX8c68t">artificial satellites</a> or <a href="/facts/Space_tether/vuK7nbJx">space tethers</a> in a fixed orientation using only the mass distribution of the orbited body and the gravitational field.  The main advantage over using active stabilization with <a href="/facts/Propellant/K88ymXRy">propellants</a>, <a href="/facts/Gyroscope/UjXGsfMq">gyroscopes</a> or <a href="/facts/Reaction_wheel/m3M5RKGF">reaction wheels</a> is the low use of power and resources. It can also reduce or prevent the risk of propellant contamination of sensitive components.
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<p>The technique exploits the <a href="/facts/Earth/HLLmDfj0">Earth</a>'s <a href="/facts/Gravitational_field/K1uTmJFy">gravitational field</a> and <a href="/facts/Tidal_forces/GJgxo7gp">tidal forces</a> to keep the spacecraft aligned along the desired orientation. The <a href="/facts/Gravity/bqAN7DdQ">gravity</a> of the Earth decreases according to the <a href="/facts/Inverse-square_law/DxG4T15l">inverse-square law</a>, and by extending the long axis perpendicular to the orbit, the "lower" part of the orbiting structure will be more attracted to the Earth.  The effect is that the satellite will tend to align its axis of minimum <a href="/facts/Moment_of_inertia/TpLLAVl7">moment of inertia</a> vertically.
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Gravity-gradient stabilization open-in-new

Gravity-gradient stabilization