Formation of the Lunar Dust Ejecta Cloud

The Lunar Dust Experiment (LDEX) on board the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission orbited the Moon from 2014 September to 2015 April and observed a dynamic, permanently present dust cloud produced by continual meteoroid bombardment. For the latitudes observed by LDEX, the sporadic background contribution to the impacting dust flux is dominated by helion (HE), apex (AP), and antihelion (AH) sources oscillating with lunar phase. Using improved impact ejecta distributions, a three-dimensional model was implemented to estimate the inner and outer ejecta cone angles from LDEX plume measurements. Expanding upon this single-plume model and the derived ejecta cone angles, we implemented a global lunar model fitted to LDEX measurements of the sporadic background to constrain the product of meteoroid impactor fluxes and ejecta mass yield per source. We use the observed asymmetry between sunward and antisunward impactor fluxes to discuss the possible contributions of β -meteoroids, in addition to the HE and AH sporadic meteoroid sources. We find that if β -meteoroids are responsible for the day/night asymmetry, they must have an impact ejecta yield of at least 10 3 .