Update on IBEX and the outer boundary of the space radiation environment

D. J. McComas

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations


The Interstellar Boundary Explorer (IBEX) mission has been remotely observing the global interaction of our heliosphere with the local interstellar medium for over three years. Initially, IBEX generated the first all-sky maps of Energetic Neutral Atoms (ENAs) emanating in from the boundaries of our heliosphere over the energy range from ∼0.1-6 keV. Using these observations, the IBEX team discovered a smoothly varying, globally distributed ENA flux overlaid by a narrow "ribbon" of significantly enhanced ENA emissions. Since the initial publication of these results in a special issue of Science magazine (November 2009), IBEX has completed five more energy-resolved sets of sky maps and discovered small but important time variations in the interaction, separated the ribbon from globally distributed ENA fluxes, measured the energy spectral shape and inferred ion source temperatures, and carried out many other observational and theoretical studies of the outer heliosphere. In a second major area of observations-direct measurements of Interstellar Neutral (ISN) atoms-just published, IBEX observations of ISN He atoms show that the speed and direction (the motion of the heliosphere with respect to the interstellar medium) is slower and from a somewhat different direction than that thought from prior Ulysses observations. These observations also show evidence for a previously unknown and unanticipated secondary population of Helium. In addition, IBEX is providing the first direct quantitative measurements of the ISN H parameters and the first direct measurements of interstellar Ne and the interstellar Neon/Oxygen abundance ratio; this ratio is significantly different than the solar abundance ratio. Finally, IBEX was recently maneuvered into a unique, long-term stable orbit, which has a very low radiation environment and requires no orbit maintenance. Thus, IBEX will likely continue to provide revolutionary observations of the outer heliosphere and local interstellar medium for many years to come.

Original languageEnglish (US)
Title of host publicationSpace Weather
Subtitle of host publicationThe Space Radiation Environment - 11th Annual International Astrophysics Conference
Number of pages6
StatePublished - 2012
Externally publishedYes
Event11th Annual International Astrophysics Conference on Space Weather: The Space Radiation Environment - Palm Springs, CA, United States
Duration: Mar 19 2012Mar 23 2012

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


Conference11th Annual International Astrophysics Conference on Space Weather: The Space Radiation Environment
Country/TerritoryUnited States
CityPalm Springs, CA

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


  • ENA
  • Heliosphere
  • IBEX
  • Interstellar Neutral
  • LISM


Dive into the research topics of 'Update on IBEX and the outer boundary of the space radiation environment'. Together they form a unique fingerprint.

Cite this