Determining Directionality of Interplanetary Dust Particles Near the Sun

International audienceInterplanetary Dust Particles (IDPs) consist of the pummeled remnants of asteroids and comets, trapped in high velocity orbits around the Sun. When these fast moving particles (>20km/s) collide with a spacecraft, they explode into a plasma cloud. These events cause voltage spikes in electric field instrument data on missions such as Voyager, Cassini, STEREO, MAVEN, WIND and Parker Solar Probe. When a dust impact occurs, the electric field antennas register a voltage spike with the highest amplitude on the antenna nearest to the impact. Prior to the August 2018 launch of Parker Solar Probe, IDP within 0.3 AU of the Sun had never been measured in-situ, and predictions for its distribution vary by orders of magnitude. Now that Parker Solar Probe data are available, we are developing algorithms to identify dust impacts and to observe IDP at distances closer to the Sun than ever before. Dust impacts have been successfully identified in different electric field instrument data products using independent detection algorithms. This provides good evidence that the identification method is reliable. The first two orbits of Parker Solar Probe data were examined and dust impact data were compared with a model which predicts the flux and direction of IDP close the the Sun. The dust populations considered in the model include particles shed by Jupiter-family comets and asteroids. Specifically, the model predicts the most likely direction of dust impacts on Parker Solar Probe. By comparing the amplitudes of dust impacts on each antenna, we used the data to determine the direction of observed impacts. During closest approach to the Sun, the model predicts that most impacts will be on the ram side of the spacecraft. The data show that antenna V4, located in the ram direction, does see the most high-amplitude impact signatures near perihelion. This, and other comparisons convey good agreement between the model and data