The Jupiter Energetic Particle Detector Instrument (JEDI) Investigation for the Juno Mission

TLDR

The Jupiter Energetic Particle Detector Instruments (JEDI) on Juno will coordinate with other spacecraft instruments to characterize Jupiter’s polar space environment and elucidate the generation of its powerful aurora. This paper outlines JEDI’s science objectives, measurement requirements, design challenges, operational procedures, calibrated performance, and initial interplanetary measurements following Juno’s 2011 launch. JEDI consists of three nearly identical units that use microchannel plates, thin foils, and solid‑state detectors to measure ion and electron energy, angle, and composition from 20 keV to >1 MeV, with time‑of‑flight, pulse‑height, and triple‑coincidence techniques to determine particle directions and suppress background. Juno is scheduled to commence its prime science operations—32 orbits spanning 1.1 × 40 RJ—in mid‑2016.

Abstract

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.