The Near-Sun Dust Environment: Initial Observations from Parker Solar Probe

Abstract: The Parker Solar Probe (PSP) spacecraft has flown into the most dense and previously unexplored region of our solar system's zodiacal cloud. While PSP does not have a dedicated dust detector, multiple instruments onboard are sensitive to the effects of meteoroid bombardment. Here, we discuss measurements taken during PSP's first two orbits and compare them to models of the zodiacal cloud's dust distribution. Comparing the radial impact rate trends and the timing and location of a dust impact to an energetic particle detector, we find the impactor population to be consistent with dust grains on hyperbolic orbits escaping the solar system. Assuming PSP's impact environment is dominated by hyperbolic impactors, the total quantity of dust ejected from our solar system is estimated to be 1-14 tons/s. We expect PSP will encounter an increasingly more intense impactor environment as its perihelion distance and semi-major axis are decreased.