Built to explore the origins, acceleration, and transport of energetic particles from the Sun, the Energetic Particle Instrument-Low energy (EPI-Lo) will make unparalleled observations of energetic particles close to the Sun and help untangle the physical processes that govern them.
APL’s EPI-Lo is one of two detectors in the Integrated Science Investigation of the Sun (ISOIS) suite on NASA’s Parker Solar Probe. It’s the newest and most versatile of a series of similar APL instruments that date back to the 1980s, including EPS on MESSENGER, PEPSSI on New Horizons, and JEDI on Juno. EPI-Lo’s octagonal body supports 80 dime-sized viewfinders, providing a wide field of view to observe energetic particles from the Sun. It details the various energies, directions, and species of electrons and ions — from protons to iron nuclei — to help determine the origin, acceleration mechanisms, and means of propagation of these particles into and throughout interplanetary space.
EPI-Lo, in combination with its suite partner called the Energetic Particle Instrument-High energy (EPI-Hi), helped make the major discovery during Parker Solar Probe’s first two flybys of the Sun that events that produce energetic particles can be tiny — far smaller than can be viewed from Earth.
Mission
Parker Solar Probe
Sun and Solar Wind
Parker Solar Probe dives closer to the Sun than humanity has ever ventured to unlock the mysteries of our nearest star.