The magnetic field is central to all plasma phenomena, from shocks and turbulence to reconnection and wave-particle interactions. The magnetometer on Solar Orbiter will measure the magnetic field local to the spacecraft with high precision and at high cadence, at 16 vectors/second throughout the entire mission with around one hour per day of data at 128 vectors/second, providing access to variations on both fluid and ion scales. As the magnetometer team moves from the qualification to the flight model build during 2015, we present the instrument's characteristics, measurement challenges and current status.