Authors: Katherine Goodrich (WVU), Ian Cohen (APL), Drew Turner (APL), Lynn Wilson III (GSFC), Steven Schwartz (Imperial)

Collisionless shocks are an important and universal phenomenon in astrophysical plasmas. The shock performs the necessary function of converting kinetic energy to thermal energy, heating the originally supersonic plasma flow until its speed is reduced and it can flow around the obstacle. The energy conversion processes that take place inside collisionless shocks, however, are not well established and have thus been a subject of interest for several decades. The closest and perhaps the most relevant collisionless shock to us humans, is the Earth’s bow shock. The bow shock has been observed by multiple spacecraft such as ISEE, Cluster, WIND, and THEMIS over more than forty years. These missions have provided us with a wealth of information on plasma conditions both upstream and downstream of the shock, however, limited instrument capabilities have prevented us from resolving the physical processes active at the shock itself.  Observations from the Magnetospheric Multiscale (MMS) mission (launched in 2015) provide particle observations on the order of 10s of milliseconds, providing an unprecedented opportunity to directly observe microscale processes inside collisionless shocks. Yet even MMS is limited in its ability to fully resolve microphysical processes in the Earth’s bow shock. In this talk, we’ll take a look back on the observational progress we’ve made in observing collisionless shock phenomena and examine the next steps we can take with future observational missions.