Synopses & Reviews
Synopsis
This is a compendium on the remote sensing of space plasmas via energetic neutral atoms (ENAs). Covered are plasmas just above Earth's upper atmosphere, around other planets, at the heliospheric boundary, and in the local interstellar medium. ENAs stem from energetic singly-charged ions through charge exchange with ambient neutral atoms (ANAs), i.e. the constituents of the gas that coexists with the space plasma of interest. Being neutral, ENAs travel on ballistic trajectories -- unfettered by magnetic fields that confine the plasmas -- to well-placed ENA sensors where they provide remote information on composition, spatial, temporal, and energy distributions of space plasmas beyond the reach of the spacecraft, thus complementary to or in-lieu of in-situ ion measurements.This monograph presents the basic concepts and tools to appreciate the challenges in ENA-instrument design, data analysis, and model simulation, with examples from our first encounters with ENAs in space to ambitious upcoming missions. It is designed to provide a solid foundation, with an extensive list of references, for graduate students and researchers interested to engage in developing ENA instruments, analyzing ENA observations and/or proposing new missions to study remote space plasmas using novel ENA instruments.
Synopsis
Astronomy has been associated with the detection of electromagnetic waves or photons from within and beyond the solar system, ranging from Radio to Gamma-ray Astronomy. Particle Astrophysics, including Neutrino and Dark-Matter Astrophysics today, started with the discovery of cosmic rays in 1911. The Space Age expanded particle observations to in-situ studies of lower energy electrons and ions with a variety of charge states in space plasmas traversed by spacecraft. Remote observation of space plasmas became possible only after the discovery of energetic neutral atom (ENAs) in space in 1950.This book is a primer for those who wish to learn more about the origins of ENAs, related detection techniques, and how ENA images and spectra can be used to study space plasmas beyond the reach of spacecraft. It tells a comprehensive story from the first encounters with ENAs in the Earth's magnetosphere to Neutral-Atom Astronomy of the edge of the heliosphere and the interstellar medium. This story includes how ion mass spectrographs evolved into ENA imagers, overcoming the technical challenges, how to extract information from ENA data, and a variety of diagnostic applications on the magnetosphere, interplanetary space, other solar-system objects, the heliospheric boundary, the local interstellar medium, and a glimpse into the future of Neutral-Atom Astronomy.The authors hope to inform and inspire readers to further enrich this field of study.