Investigation of Water Interactions With Apollo Lunar Regolith Grains - Data Files
Jones, Brant M.
Dyar, M. Darby
Orlando, Thomas M.
MetadataShow full item record
Desorption activation energies of chemisorbed water on Apollo lunar samples 14163 and 10084 were determined by temperature program desorption (TPD) experiments conducted under ultra-high vacuum conditions. Desorption at the grain/vacuum interface and desorption/transport of water though the porous medium with re-adsorption were found to reproduce the experimental TPD signal. Signal from the grain/vacuum interface yielded desorption activation energies and site probability distributions. Highland sample 14163 exhibited a broad distribution of binding site energies peaking at 60 kJ mol-1 while mare sample 10084 exhibited a narrower distribution of binding site energies peaking at 65 kJ mol-1. Water desorption from the lunar surface over a typical lunar day was simulated with the measured coverage dependent activation energies of the mare and highland samples. The resulting desorption profile of water through a lunar temperature cycle is in general agreement with Lunar Reconnaissance Orbiter (LRO) Lyman-α Mapping Project (LAMP) spacecraft-based observations of trends for both highland and mare assuming ~1% submonolayer coverage and that photostimulated desorption is neglected.