Interpretation of Streaks from the Wide-Field Imager for Parker Solar Probe (WISPR)

The Wide-Field Imager for Parker Solar Probe (WISPR/PSP) has recorded intermittent bright streaks radiating across its field of view during close encounters with the Sun. As part of a broader effort to ensure PSP safety in the near Sun dust environment, we explore the hypothesis that some observed “streaks” are images of solar-illuminated particulate ejecta following dust hypervelocity impacts on the spacecraft thermal protection system (TPS) or radiative cooling system. We present a geometrical model for illuminated grains moving across the WISPR field of view, enabling the inference of source size, distance, and spatial origin. A software framework is developed and used for tracing streaks in calibrated L3 images and analyzing the streaks' individual and statistical properties. Evidence is consistent with some “conical” populations of streaks originating from well-defined point-like regions on the PSP radiator or TPS, implying that a hypervelocity impact may have generated the observed particles from those locations.