New Horizons’ Student Dust Counter: Potential Compositional Insights at 61 AU Heliocentric Distance

The Venetia Burney Student Dust Counter (SDC) aboard New Horizons provides unique insights into dust dynamics beyond 17 AU and extending through the Kuiper Belt. SDC’s ability to detect dust grains larger than 10⁻¹² grams allows it to map dust size and density distributions along the New Horizons’ flight path, presenting unparalleled data up to 61 AU. Recent SDC observations reveal fluxes two to three times higher than earlier models predicted beyond 45 AU. These findings, in conjunction with modern simulations, suggest that the composition of dust grains—ranging from refractory silicates to volatile ices—plays a more significant role in the outer solar system dust density than previously considered, with icy grains demonstrating unique outward migration due to erosion rates that far exceed those of refractory grains.

We present updated dust flux measurements out to 61 AU, detailed comparisons with new numerical simulations of pure ice and pure refractory grains, and preliminary results of mixed-composition grains. The results underscore the importance of continued efforts to model mixed refractory-volatile grains to accurately interpret the Kuiper Belt’s dust production and transport mechanisms. As New Horizons advances to the edge of the solar system, SDC measurements continue to refine our understanding of the outer solar system’s dust environment, extent, and its implications for dust disks around other stars.