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Detections of lunar exospheric ions by the LADEE neutral mass spectrometer
Author(s) -
Halekas J. S.,
Benna M.,
Mahaffy P. R.,
Elphic R. C.,
Poppe A. R.,
Delory G. T.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl064746
Subject(s) - exosphere , ion , physics , photoionization , atmosphere (unit) , ionosphere , population , atomic physics , plasma , astrobiology , astronomy , ionization , meteorology , demography , quantum mechanics , sociology
Abstract The Lunar Atmosphere and Dust Environment Explorer (LADEE) Neutral Mass Spectrometer (NMS), operating in ion mode, provides sensitive detections of ions from the lunar exosphere. By analyzing ion‐mode data from the entire mission, utilizing Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) plasma and magnetic field measurements to organize NMS data and eliminate background sources, we identify highly significant detections of lunar ions at mass per charge of 2, 4, 12, 20, 28, 39, and 40, moderately significant detections at 14 and 23, and weak detections at 24, 25, and 36. Unlike many previous observations of Moon‐derived ions, an outward pointing viewing geometry ensures that these ions originate from the exosphere, rather than directly from the surface. For species with known neutral distributions, inferred ion production rates appear consistent with expectations for both magnitude and spatial distribution, assuming photoionization as the predominant source mechanism. Unexpected signals at mass per charge 12 and 28 suggest the presence of a significant exospheric population of carbon‐bearing molecules.