  The NASA New Horizons spacecraft flies past Pluto on July 14, 2015, carrying
two instruments that detect charged particles. Pluto has a tenuous, extended
atmosphere that is escaping the weak gravity of the planet. The interaction of
the solar wind with the escaping atmosphere of Pluto depends on solar wind
conditions as well as the vertical structure of the atmosphere. We have
analyzed Voyager 2 particles and fields measurements between 25 and 39 AU and
present their statistical variations. We have adjusted these predictions to
allow for the declining activity of the Sun and solar wind output. We summarize
the range of SW conditions that can be expected at 33 AU and survey the range
of scales of interaction that New Horizons might experience. Model estimates
for the solar wind stand-off distance vary from approximately 7 to 1000 RP with
our best estimate being around 40 RP (where we take the radius of Pluto to be
RP=1184 km).
