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

The Solar WindAround Pluto(SWAP) instrument on New Horizons will measure the interaction between the solar windand 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 Plutofor 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 Plutoand Charon during the flyby. To meet these unique requirements, we combined a cylindrically symmetric retarding potentialanalyzer with small deflectors, a top-hat analyzer, and a redundant/coincidence detection scheme. This configuration allows for highly sensitive measurements and a controllable energy passbandat all scan angles of the spacecraft.