  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.
