Dangerous dust clouds above lunar surface

Abstract: Time-limited space missions may miss rare occurrences of very dense clouds of lunar dust. At the same time, the information provided by the Earth-based monitoring of the Moon during at least the last three centuries still remains unused. In the present study, we fill this data analysis gap. The survey of historical reports of the 18-19 centuries about supposed lunar atmosphere manifestations, as well as the available data on too long-lasting stellar occultations by the lunar limb, enable us revealing numerous evidences of the lunar dust phenomena. By modeling of the conditions of such observations, we determine the geometrical parameters of the dust clouds, which scattered the sunlight during the particular events. Using this information, as well as the Mie scattering theory, we estimate the concentration of dust and its damaging effect at different orbits of a possible spacecraft. It was found that the some observed dust clouds of sub-micron grains could crash a space-vehicle at the low (<10 km) altitudes, similar to the incidents with landers Vikram, Beresheet, Hakuto-R M1, Luna-25, etc. The statistics of dust clouds' appearance enabled a reconstruction of a typical shape of a local dust cloud which resembles the shape of an impact plume. This, together with the revealed seasonal periodicity of observational manifestations of the dust phenomena, confirms a hypothesis on the meteoroid impact nature of the majority of the circumlunar dust clouds. At the same time, the discovered additional periodicity of the dust cloud appearance at half of synodic lunar month argue for an additional non-impact source of the circumlunar dust, connected with the lunar outgassing events, controlled by the solar tidal effects, completely unstudied. Moreover, the tendency of dust clouds to be observed during the low-level solar activity raises a question on possible dust pick up by the solar wind flow.