Plutos interaction with its space environment: Solar Wind, Energetic Particles & Dust

TL;DR

This study details how Pluto interacts with solar wind, energetic particles, and dust, revealing a small interaction region, particle acceleration, and low dust density, based on New Horizons measurements during its 2015 flyby.

Contribution

It provides new in-situ measurements of Pluto's space environment, highlighting the small size of its interaction region and the characteristics of energetic particles and dust around Pluto.

Findings

Interaction region confined within 6 Pluto radii

Ions are accelerated or deflected around Pluto

Dust density in the Pluto system is very low

Abstract

The New Horizons spacecraft carried three instruments that measured the space environment near Pluto as it flew by on 14 July 2015. The Solar Wind Around Pluto instrument revealed an interaction region confined sunward of Pluto to within about 6 Pluto radii. The surprisingly small size is consistent with a reduced atmospheric escape rate as well as a particularly high solar wind flux. The Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) observations suggested ions are accelerated and-or deflected around Pluto. In the wake of the interaction region PEPSSI observed suprathermal particle fluxes about one tenth the flux in the interplanetary medium, increasing with distance downstream. The Student Dust Counter, which measures radius greater than 1.4 um grains, detected 1 candidate impact from 5days before to 5 days after closest approach, indicating an upper limit for the dust density in the Pluto system of 4.6 per cubic km.