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If an astronaut takes a magnet, or even a map-reading compass, into inter-planetary space, what, if anything, does the needle point to?
If an astronaut takes a magnet into space, what, if anything, does the needle point to?
QuoteIf an astronaut takes a magnet into space, what, if anything, does the needle point to?Satellites in Low Earth Orbit often use a Magnetorquer to orient the satellite in space, by using Earth's magnetic field.Small satellites can use a permanent magnet; larger satellites tend to use electromagnets.This avoids the moving parts of momentum wheels (momentum wheel failure is what eventually disabled the Kepler extrasolar planet survey satellite).The torque available from Earth's magnetic field is very small; an astronaut's normal body movements would exert a greater torque, so the magnet wouldn't help orient the astronaut (or his spaceship) at all. Manned missions tend to use small rocket thrusters.When and if Earth's magnetic field decays to zero, changes to a quadrupole configuration or flips entirely, satellites using Magnetorquers could lose control of their orientation.