Abstract
The Moon is known to have a collision-free tenuous atmosphere. Its source mechanism links to the environment in surrounding and the surface evolution. The origins of lunar atmosphere are believed to be the photon stimulated desorption by solar radiation (PSD), solarwind sputtering, micrometeorite vaporization.
For identifying which source mechanism is predominant, we have made ground-based observations of the lunar sodium atmosphere and construction of atmospheric model. Observations were carried out at the Iitate Observatory using a combination of a 60cm telescope and a 1m spectrograph with altitude coverage of 600km from the lunar surface.
The Monte-Carlo simulation model took account of jumping and adsorption of produced particles on the lunar surface. As a result of comparison between the observed data and the model, it was found that the source rate of PSD mechanism is predominant, suggesting that PSD should be the dominating source for lunar sodium atmosphere.
