Journal article
Lunar pickup ions observed by ARTEMIS: Spatial and temporal distribution and constraints on species and source locations
Journal of Geophysical Research: Planets, Vol.117(E6), E06006
06/2012
DOI: 10.1029/2012JE004107
Abstract
[1] ARTEMIS observes pickup ions around the Moon, at distances of up to 20,000 km from the surface. The observed ions form a plume with a narrow spatial and angular extent, generally seen in a single energy/angle bin of the ESA instrument. Though ARTEMIS has no mass resolution capability, we can utilize the analytically describable characteristics of pickup ion trajectories to constrain the possible ion masses that can reach the spacecraft at the observation location in the correct energy/angle bin. We find that most of the observations are consistent with a mass range of ∼20–45 amu, with a smaller fraction consistent with higher masses, and very few consistent with masses below ∼15 amu. With the assumption that the highest fluxes of pickup ions come from near the surface, the observations favor mass ranges of ∼20–24 and ∼36–40 amu. Although many of the observations have properties consistent with a surface or near-surface release of ions, some do not, suggesting that at least some of the observed ions have an exospheric source. Of all the proposed sources for ions and neutrals about the Moon, the pickup ion flux measured by ARTEMIS correlates best with the solar wind proton flux, indicating that sputtering plays a key role in either directly producing ions from the surface, or producing neutrals that subsequently become ionized.
Details
- Title: Subtitle
- Lunar pickup ions observed by ARTEMIS: Spatial and temporal distribution and constraints on species and source locations
- Creators
- J. S Halekas - University of California, BerkeleyA. R Poppe - University of California, BerkeleyG. T Delory - University of California, BerkeleyM Sarantos - University of Maryland, Baltimore CountyW. M Farrell - Ames Research CenterV Angelopoulos - University of California, Los AngelesJ. P McFadden - University of California, Berkeley
- Resource Type
- Journal article
- Publication Details
- Journal of Geophysical Research: Planets, Vol.117(E6), E06006
- Publisher
- Blackwell Publishing Ltd
- DOI
- 10.1029/2012JE004107
- ISSN
- 0148-0227
- eISSN
- 2156-2202
- Number of pages
- 13
- Language
- English
- Date published
- 06/2012
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199725902771
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