Premium
Methane in the lunar exosphere: Implications for solar wind carbon escape
Author(s) -
Hodges, R. Richard
Publication year - 2016
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 - 10.1002/2016gl068994
Subject(s) - exosphere , methane , astrobiology , atmosphere (unit) , atmospheric sciences , solar wind , carbon fibers , environmental science , physics , geology , materials science , chemistry , meteorology , plasma , ion , organic chemistry , quantum mechanics , composite number , composite material
A positive identification of methane in the lunar exosphere has been made in data from the neutral mass spectrometer on the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft. Like argon‐40, methane is adsorbed on the lunar surface during nighttime. However, higher activation energies for methane delay its desorption at sunrise by about an hour local time, creating a postsunrise bulge with peak concentration of approximately 400–450 molecules cm −3 at a reference altitude of 12 km, which is just above the highest topographic feature on the Moon. The rate of escape of carbon as methane derived from the LADEE data is estimated to be in the range 1.5–4.5 × 10 21 s −1 . A lower bound for solar carbon escape derived separately from Apollo sample analyses is 3.4 × 10 21 s −1 .