High Quality Content by WIKIPEDIA articles! Spacecraft magnetometers are magnetometers used aboard spacecraft and satellites, mostly for scientific investigations, plus attitude sensing. Magnetometers are among the most widely used scientific instruments in exploratory and observation satellites. These instruments were instrumental in the discovery of the Van Allen radiation belts around Earth by Explorer 1, and have detailed the magnetic fields of the Earth, Moon, Sun, Mars, Venus and other planets. There are ongoing missions using magnetometers, including attempts to define the shape and activity of Saturn`s core.