Direct multipoint observations capturing the reformation of a supercritical fast magnetosonic shock

The four MMS spacecraft were separated by several hundred kilometers, comparable to suprathermal ion gyroradius scales or several ion inertial lengths.

At least half of the shock reformation cycle was observed, with a new shock ramp rising up out of the "foot" region of the original shock ramp. Using the multipoint observations, we convert the observed time-series data into distance along the shock normal in the shock's rest frame. That conversion allows for a unique study of the relative spatial scales of the shock's various features, including the shock's growth rate, and how they evolve during the reformation cycle.