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

TL;DR

The Parker Solar Probe's initial observations reveal the density and distribution of dust near the Sun, indicating a population of hyperbolic impactors escaping the solar system, with implications for understanding the solar system's dust environment.

Contribution

This study provides the first measurements of the near-Sun dust environment using PSP data and compares them to existing dust distribution models.

Findings

Impactor population is consistent with hyperbolic dust grains escaping the solar system.

Estimated dust ejection rate from the solar system is 1-14 tons per second.

Impact environment is expected to intensify as PSP approaches closer to the Sun.

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.