The Jupiter Energetic Particle Detector Instruments (JEDI) on the Juno Jupiter polar-orbiting, atmosphere-skimming, mission to Jupiter will coordinate with the several other space physics instruments on the Juno spacecraft to characterize and understand the space environment of Jupiter's polar regions, and specifically to understand the generation of Jupiter's powerful aurora. JEDI comprises 3 nearly-identical instruments and measures at minimum the energy, angle, and ion composition distributions of ions with energies from H:20 keV and O: 50 keV to > 1 MeV, and the energy and angle distribution of electrons from < 40 to > 500 keV. Each JEDI instrument uses microchannel plates (MCP) and thin foils to measure the times of flight (TOF) of incoming ions and the pulse height associated with the interaction of ions with the foils, and it uses solid state detectors (SSD's) to measure the total energy (E) of both the ions and the electrons. The MCP anodes and the SSD arrays are configured to determine the directions of arrivals of the incoming charged particles. The instruments also use fast triple coincidence and optimum shielding to suppress penetrating background radiation and incoming UV foreground. Here we describe the science objectives of JEDI, the science and measurement requirements, the challenges that the JEDI team had in meeting these requirements, the design and operation of the JEDI instruments, their calibrated performances, the JEDI inflight and ground operations, and the initial measurements of the JEDI instruments in interplanetary space following the Juno launch on 5 August 2011. Juno will begin its prime science operations, comprising 32 orbits with dimensions 1.1 × 40 RJ, in mid-2016.

The Energetic Particle Detector (EPD) Investigation is one of 5 fields-andparticles investigations on the Magnetospheric Multiscale (MMS) mission. MMS comprises 4 spacecraft flying in close formation in highly elliptical, near-Earth-equatorial orbits targeting understanding of the fundamental physics of the important physical process called magnetic reconnection using Earth's magnetosphere as a plasma laboratory. EPD comprises two sensor types, the Energetic Ion Spectrometer (EIS) with one instrument on each of the 4 spacecraft, and the Fly's Eye Energetic Particle Spectrometer (FEEPS) with 2 instruments on each of the 4 spacecraft. EIS measures energetic ion energy, angle and elemental compositional distributions from a required low energy limit of 20 keV for protons and 45 keV for oxygen ions, up to > 0.5 MeV (with capabilities to measure up to > 1 MeV). FEEPS measures instantaneous all sky images of energetic electrons from 25 keV to > 0.5 MeV, and also measures total ion energy distributions from 45 keV to > 0.5 MeV to be used in conjunction with EIS to measure all sky ion distributions. In this report we describe the EPD investigation and the details of the EIS sensor. Specifically we describe EPD-level science objectives, the science and measurement requirements, and the challenges that the EPD team had in meeting these requirements. Here we also describe the design and operation of the EIS instruments, their calibrated performances, and the EIS in-flight and ground operations. Blake et al. (The Flys Eye Energetic Particle Spectrometer (FEEPS) contribution to the Energetic Particle Detector (EPD) investigation of the Magnetospheric Magnetoscale (MMS) Mission, this issue) describe the design and operation of the FEEPS instruments, their calibrated performances, and the FEEPS in-flight and ground operations. The MMS spacecraft will launch in early 2015, and over its 2-year mission will provide comprehensive measurements of magnetic reconnection at Earth's magnetopause during the 18 months that comprise orbital phase 1, and magnetic reconnection within Earth's magnetotail during the about 6 months that comprise orbital phase 2.Keywords NASA mission · Magnetospheric multiscale · Magnetosphere · Magnetic reconnection · Space plasma · Particle acceleration 1 EPD Introduction, Background, Science Goals Background and OverviewThe purpose of NASA's Magnetospheric Multiscale (MMS) mission, as described by Burch et al. (this issue), is to provide understanding of the fundamental physics of the critical energy conversion process of magnetized space plasmas called Magnetic Reconnection. Magnetic reconnection is a spatially localized process that converts magnetic energy that is derived from the flow energy of ionized gases (plasmas), into particle energy in the form of different forms of plasma flow, heating, and particle energization To provide that understanding, the MMS mission comprises 4 spacecraft that fly in formation (10 to 400 km apart) in highly elliptical orbits (1.2 × 12 to 1.2 × 25 RE), thereby ob...

The Energetic Particle Detector (EPD) Investigation is one of 5 fields-andparticles investigations on the Magnetospheric Multiscale (MMS) mission. MMS comprises 4 spacecraft flying in close formation in highly elliptical, near-Earth-equatorial orbits targeting understanding of the fundamental physics of the important physical process called magnetic reconnection using Earth's magnetosphere as a plasma laboratory. EPD comprises two sensor types, the Energetic Ion Spectrometer (EIS) with one instrument on each of the 4 spacecraft, and the Fly's Eye Energetic Particle Spectrometer (FEEPS) with 2 instruments on each of the 4 spacecraft. EIS measures energetic ion energy, angle and elemental compositional distributions from a required low energy limit of 20 keV for protons and 45 keV for oxygen ions, up to > 0.5 MeV (with capabilities to measure up to > 1 MeV). FEEPS measures instantaneous all sky images of energetic electrons from 25 keV to > 0.5 MeV,

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