Dust measurements at the edge of the solar system Original Research Article

We discuss possible measurement techniques and observation strategies for the detection of interstellar dust particles from spacecraft which travel to the boundaries of the solar system. Large interstellar dust particles as well as dust from Kuiper belt objects will be measured within the heliosphere. The radial speed that is required for an Interstellar Probe mission is favorable for detection methods that are based on the impact ionization of dust particles. This also allows to obtain information about the dust elemental composition. The dust fluxes depend on the influence of radiation pressure, solar gravity, and Lorentz forces on the interstellar dust as well as on the production and evolution of dust from Kuiper belt objects. All the listed effects are correlated to the dust properties and hence allow for a comparison to models that are obtained from astronomical studies. The majority of interstellar dust particles of sizes below 0.1 μm are deflected from entering the heliosphere. They will be measured beyond the heliopause. We use a simple model of the heliospheric transition region to calculate the velocity distributions of these interstellar grains in the neighborhood of the heliosphere. Different assumptions about the interstellar magnetic field and the structure of the plasma flow are considered. We find that the distributions are sensitive to the structure of the heliospheric transition region, in particular to the presence of a sharp bow shock.