Energetic neutral atom imaging of the heliospheric boundary region

Mike Gruntman, Edmond C. Roelof, Donald G. Mitchell, Hans J. Fahr, Herbert O. Funsten, David J. McComas

Research output: Contribution to journalArticlepeer-review

126 Scopus citations


Energetic neutral atom (ENA) imaging is a powerful technique, which can remotely probe the properties of distant hot plasmas. Hot plasmas are abundant at the heliospheric boundary, the region where the expanding solar wind meets the surrounding local interstellar cloud. Here we present a new concept for imaging this boundary in ENA fluxes. Heliospheric ENAs are born from charge exchange between energetic protons and the background interstellar atomic hydrogen gas. The technique is ideal for studying the asymmetric three-dimensional heliospheric interface region remotely, from 1 AU. We show that ENA imaging in the 0.2-6 keV energy range will establish the nature of the termination shock and properties of hot proton populations in the heliosheath. We also examine how the evolution of pickup proton populations at and beyond the shock can be explored. Global heliosphere ENA images will distinguish among the competing models of the interaction between the Sun and the local interstellar medium, and they will reveal the physics of important processes in the interface region. Heliospheric ENA fluxes are exceptionally weak, which makes imaging implementation difficult. Nonetheless, we show how single-pixel ENA sensors can image the heliosphere from a spinning spacecraft on a typical mission near 1 AU. The required instrumentation is briefly discussed.

Original languageEnglish (US)
Article number2000JA000328
Pages (from-to)15767-15781
Number of pages15
JournalJournal of Geophysical Research: Space Physics
Issue numberA8
StatePublished - Aug 1 2001
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Space and Planetary Science


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