Abstract
The Energetic Particle Detector (EPD) Investigation is one of 5 fields-and-particles 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.
Highlights
Background and OverviewThe purpose of NASA’s Magnetospheric Multiscale (MMS) mission, as described by Burch et al, 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, 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 obtaining simultaneous, multipoint measurements of known reconnection sites on the dayside on Earth’s magnetopause and within Earth’s comet-like magnetic tail on the nightside
Each MMS spacecraft hosts a comprehensive array of particles and fields instruments that make localized in situ measurements of electron and ion energy, directional, and species distributions from low to high energies; the time and spatially varying electric and magnetic field vectors; and the electric and magnetic fields of the waves that propagate within the plasmas
Summary
The 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. The Energetic Particle Detector (EPD) investigation contributes to these measurements by measuring the high energy portions of the electron and ion energy, directional, and compositional distributions. The EIS instruments use microchannel plate (MCPs) and SSDs, configured to measure ion times-of-flight (TOF) and particle energies to obtain clean measurements of ion spectra and ion composition for 6 different views within a plane. We will referring to these sister instruments, and the respective overview papers, a number of times within the present paper
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