MESSENGER magnetometer data vs. simulation magnetic field along the satellite trajectory. (a) Magnetic field module, (b) B_x, (c) B_y, and (d) B_z components. The dashed red lines indicate the fraction of the satellite trajectory that is inside the SMS in the simulation. The dotted blue line shows the satellite crossing of the compression front in the simulation. The dashed green lines show the satellite access and exit of the magnetosphere.