Mass (including boom): 4.4 kilograms (9.7 pounds)
Power: 4.2 watts
Development: NASA Goddard Space Flight Center, Greenbelt, Md., and Johns Hopkins University Applied Physics Laboratory
A three-axis, ring-core fluxgate detector, MAG characterizes Mercury’s magnetic field in detail, helping scientists determine the field’s precise strength and how it varies with position and altitude. Obtaining this information is a critical step toward determining the source of Mercury’s magnetic field.
The MAG sensor is mounted on a 3.6-meter (nearly 12-foot long) boom that keeps it away from the spacecraft’s own magnetic field. The sensor also has its own sunshade to protect it from the Sun when the spacecraft is tilted to allow for viewing by the other instruments. While in orbit at Mercury the instrument will collect magnetic field samples at 50-millisecond to one-second intervals; the rapid sampling will take place near Mercury’s magnetosphere boundaries.