Using ARTEMIS pickup ion observations to place constraints on the lunar atmosphere

J. S Halekas; A. R Poppe; G. T Delory; M Sarantos; J. P McFadden

doi:10.1029/2012JE004292

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Using ARTEMIS pickup ion observations to place constraints on the lunar atmosphere

Journal article

Peer reviewed

Using ARTEMIS pickup ion observations to place constraints on the lunar atmosphere

J. S Halekas, A. R Poppe, G. T Delory, M Sarantos and J. P McFadden

Journal of geophysical research. Planets, Vol.118(1), pp.81-88

01/2013

DOI: 10.1029/2012JE004292

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Abstract

We present a method for deriving constraints on the structure and composition of the lunar atmosphere by using pickup ion measurements from ARTEMIS, mapping observed fluxes from the spacecraft location to derive production rates at the source region, and fitting to a parameterized neutral atmosphere model. We apply this technique to ~12 min of high‐resolution burst data collected by ARTEMIS P2 above the sunlit lunar surface, in the dawnside terrestrial magnetosheath. During this time period, ARTEMIS observed multiple velocity components, requiring the presence of multiple species and/or source regions. We use species at or near masses 12, 16, 24, 28, and 40 to derive a best‐fit model that proves consistent with most known abundances and limits on neutral densities as well as predictions thereof. However, we find indications of large neutral abundances at mass ~16, exceeding optical limits on oxygen by a factor of ~20, possibly indicating either “seeding” of the Moon by terrestrial oxygen during its magnetotail passage or significant contributions by OH or CH4. We also derive new upper limits on the abundance of OH and Al in the atmosphere. Key pointsWe use pickup ion data from ARTEMIS to constrain the lunar atmosphereA mix of 12,16,24,28,40 fits data. We also obtain new upper limits on Al & OHOur model has large density at mass 16, suggesting excess O, or OH or CH4

atmosphere

Moon

pickup ions

Details

Title: Subtitle: Using ARTEMIS pickup ion observations to place constraints on the lunar atmosphere
Creators: J. S Halekas - University of California, Berkeley
A. R Poppe - University of California, Berkeley
G. T Delory - University of California, Berkeley
M Sarantos - University of Maryland, Baltimore
J. P McFadden - University of California, Berkeley
Resource Type: Journal article
Publication Details: Journal of geophysical research. Planets, Vol.118(1), pp.81-88
DOI: 10.1029/2012JE004292
ISSN: 2169-9097
eISSN: 2169-9100
Number of pages: 8
Grant note: NASA (NAS5‐02099)
Language: English
Date published: 01/2013
Academic Unit: Physics and Astronomy
Record Identifier: 9984199736502771

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