A Plasma Never Forgets: The image depicts the ion energy distribution function during the evolution of the nonmagnetized electrostatic current-carrying instability relevant to hollow cathode sputtering and the lifetime of spacecraft electric propulsion devices. On velocity-velocity axes, it illustrates the relative tendency of high-energy ions to proceed in various directions, in increasing energy from dark to light, including the transverse and backward directions that are likely to impinge spacecraft. Contributors: Contributors: Ken Hara, Stanford University; Iain Boyd, University of Colorado