A future observational plan of dust particles around the Moon by LDM (Lunar Dust Monitor) onboard the orbiter of the next Japanese lunar mission

This paper describes our future observation of the dust environment around the Moon by the Lunar Dust Monitor (LDM) to increase our knowledge regarding how the dust inflow and outflow contribute to lunar surface materials. Dust observation in lunar orbit is of great significance to better understand the source of supply of lunar materials, the evolution of lunar regolith, ejecta escaped from the Moon's gravitational sphere, and the inflow dust related to meteor streams. Although there have been several past missions of dust observation around the Moon, the origins of the observed dust particles in those missions could not be identified due to low statistics of dust flux or low accuracy of determining their arrival directions. To quantitatively study dust particles around the Moon, we need further data for improved statistics. In a feasibility study, we propose the instrumentation of a LDM that can measure the mass and speed of dust particles with a large detection area of 0.04 m(2). With this LDM, we aim at quantitatively studying dust particles around the Moon, inclusive of interplanetary dust, beta meteoroids, interstellar dust, and possibly lunar dust that originate from the surface materials of the Moon. In this paper, we summarize the significance of dust particles around the Moon and report an overview of our instrument proposed for the next Japanese lunar mission SELENE-2.