File:MESSENGER - EPPS.jpg

English: "EPPS will measure the mix and characteristics of charged particles in and around Mercury’s magnetosphere using an Energetic Particle Spectrometer (EPS) and a Fast Imaging Plasma Spectrometer (FIPS). Both are equipped with time-of-flight and energy-measurement technologies to determine simultaneously particle velocities and elemental species. From its vantage point near the top deck of the spacecraft, EPS will observe ions and electrons accelerated in the magnetosphere. EPS has a 160° by 12° field of view for measuring the energy spectra and pitch-angle distribution of these ions and electrons. Mounted on the side of the spacecraft, FIPS will observe low-energy ions coming from Mercury’s surface and sparse atmosphere, ionized atoms picked up by the solar wind, and other solar-wind components. FIPS provides nearly full hemispheric coverage. "