3:30 PM - 4:50 PM
Despite four decades of in situ study of the Earth’s bow shock, and collisionless shocks elsewhere within the interplanetary medium, there is still no quantitative explanation for the way the incident bulk flow energy is divided amongst electrons, thermal protons and other ions, energetic particles, and electromagnetic Poynting flux. In physical terms, although the total shock energetics can be calculated, the equation of state necessary to describe the internal processes does not exist. Statistically, the relative electron heating decreases as the inverse of the shock number – a result that seems to hold not only for the rather modest values at Earth, but also higher Mach numbers in the outer solar system and supernovae. Recently we emphasised the non-local nature of electron dynamics at the bow shock, suggesting that the local shock parameters were insufficient to determine the local shock properties. In fact, the controlling influence takes place near the point of tangency between the interplanetary magnetic field and the curved bow shock. This puts MMS in a prime position to explore the detailed physics occurring at such nearly-exactly-perpendicular shocks where the role of adiabatic vs non-adiabatic particle motion, contributions due to electric field spikes, and pre-conditioning electron motion through the extended shock foot all probably play a role.