Magnetometer (MAG) observes Interplanetary Magnetic Field (IMF). MAG is two independent tri-axial ring core fluxgate magnetometer sensors. MAG measures the magnetotail, magnetosheath, and interplanetary magnetic fields Each magnetometer measures the ambient vector magnetic field over a wide dynamic range. The two identical sensors are mounted on a 5-m coilable boom: one at the middle and the other at the end of the boom.
Both magnetometers sample the ambient magnetic field at a raw sample rate of 20 vector samples per second. The magnetometers are flying on nine currently-operational NASA missions: Parker Solar Probe, Juno, MAVEN, Van Allen Probes, STEREO, Wind, DSCOVR, ACE, and Voyager. The MAG team is also currently building the same magnetometers for the Astrobotics lunar lander and GTOSat cubesat missions.