Physical Sciences Research Projects

We are employing high-resolution Fabry-Perot spectroscopy of neutral sodium and potassium emission to investigate the morphology and dynamics of the lunar sodium exosphere. Likely atmosphere source mechanisms are thermal desorption, photo-desorption, ion sputtering, and meteoric impact ablation.

Their relative importance remains uncertain, both with regard to spatial and to temporal trends. Once released, sputtered gases in the lunar atmosphere can be pulled back to the regolith by gravity, escape to space, get pushed away by solar radiation pressure, or become photoionized and swept away by the solar wind. To test hypotheses about the sources, sinks, and escape of the lunar atmosphere, velocity-resolved observations under different lunar phases, altitudes, latitudes, and time histories are being made to help understand factors that link resultant morphologies to sources and solar radiation effects. These observations will help constrain atmospheric and surface-process modeling, and help quantify the source and escape mechanisms.