Unexpected energetic particle observations near the Sun by Parker Solar Probe and Solar Orbiter

Solar Energetic Particles (SEPs) constitute an important contributor to the characterization of the space environment. They are emitted from the Sun in association with solar flares and Coronal Mass ejection (CME)-driven shock waves. SEP radiation storms may have durations from a period of hours to days or even weeks and have a large range of energy spectrum profiles. These events pose a threat to modern technology strongly relying on spacecraft, are a serious radiation hazard to humans in space, and are additionally of concern for avionics and commercial aviation in extreme circumstances. However, our knowledge of the origin, acceleration and transport of these particles from close to the Sun through the interplanetary medium has advanced dramatically in the last 40 years, many puzzles have still remained unsolved due to the scarcity of in situ measurements well inside 1 AU. The Solar Orbiter (SolO) ESA mission and NASA Parker Solar Probe (PSP) pioneering missions have been providing unprecedented measurements of energetic particles in the near-Sun environment. In this work, unexpected energetic particle observations as measured by the PSP Integrated Science Investigation of the Sun (ISIS) and the SolO Energetic Particle Detector (EPD) experiments will be presented which revealed surprises that challenge our understanding.