Micrometeoroid Impact Rate Analysis for an Artemis-Era Lunar Base

NASA's Artemis Mission aims to return astronauts to the Moon and establish a base at the lunar south pole. A key challenge is understanding the threat from micrometeoroid impacts, which are too small to monitor directly. Using NASA's Meteoroid Engineering Model 3 (\texttt{MEM~3}), we estimate micrometeoroid impact rates on a base comparable in size to the International Space Station (100\,m $\times$ 100\,m $\times$ 10\,m). We find that a lunar base would experience $\sim$15,000--23,000 incident impacts per year by micrometeoroids with a mass range of $10^{-6}$--$10^{1}$~g, depending on location -- with minima at the lunar poles, a maximum near the sub-Earth longitude, and a factor of $\sim$1.6 variation between the two. To assess the mitigating effect of protection systems, we present a functional relationship describing the number of impacts that penetrate the shielding as a function of the minimum meteoroid mass capable of penetrating the shield -- the ``critical mass.'' We estimate that state-of-the-art Whipple shields protect against $\sim$99.9997\% of micrometeoroids. By re-running \texttt{MEM~3} with a minimum mass equal to the critical mass of modern Whipple shields, we determine that a shielded lunar base would experience $\sim$0.024--0.037 penetrating impacts per year -- again with minima at the poles and a maximum near the sub-Earth longitude. These results indicate that (1) the lunar poles are optimal for sustained habitation, (2) gravitational focusing by Earth dominates over its geometric shielding for this micrometeoroid flux, and (3) current shielding technology can reduce micrometeoroid threats by nearly five orders of magnitude, making long-duration lunar habitation feasible.