The Solar Wind Around Pluto (SWAP) Instrument Aboard New Horizons

TL;DR

The SWAP instrument on New Horizons measures solar wind interactions with Pluto's atmosphere, providing first-time plasma data to understand atmospheric loss and plasma dynamics at Pluto.

Contribution

This paper introduces the SWAP instrument's design and capabilities for measuring plasma-ion interactions at Pluto during the New Horizons flyby.

Findings

First measurements of solar wind interaction at Pluto

Characterization of atmospheric loss rate from Pluto

Innovative instrument design enabling comprehensive plasma scans

Abstract

The Solar Wind Around Pluto (SWAP) instrument on New Horizons will measure the interaction between the solar wind and ions created by atmospheric loss from Pluto. These measurements provide a characterization of the total loss rate and allow us to examine the complex plasma interactions at Pluto for the first time. Constrained to fit within minimal resources, SWAP is optimized to make plasma-ion measurements at all rotation angles as the New Horizons spacecraft scans to image Pluto and Charon during the flyby. In order to meet these unique requirements, we combined a cylindrically symmetric retarding potential analyzer (RPA) with small deflectors, a top-hat analyzer, and a redundant/coincidence detection scheme. This configuration allows for highly sensitive measurements and a controllable energy passband at all scan angles of the spacecraft.