The surfaces of airless bodies like the Moon are directly exposed to the space environment and as a result change both physically and chemically over time due to processes collectively known as space weathering. The rate of space weathering on the lunar landscape is poorly understood because these two facets of surface evolution have yet to be fully linked. Macroscopic physical processes like impact cratering disrupt and overturn the upper surface layer comprised of loose, unconsolidated material known as soil or regolith (Shoemaker et al., 1969). As the landscape evolves and material is transported across the surface, the microscopic chemical structure of material on the surface is altered by micrometeorite impacts, cosmic rays, and the solar wind (Hapke, 2001; Pieters & Noble, 2016). These processes are deeply coupled since the amount of time material spends on the surface exposed to the space environment depends on the rate at which material is cycled in and out of the uppermost regolith layer. Analysis of lunar soil properties from Apollo program samples and remote sensing surface reflectance measurements have characterized the degree of space weathering, or maturity, of the lunar regolith (Lucey Abstract The lunar landscape evolves both physically and chemically over time due to impact cratering and energetic processes collectively known as space weathering. Despite returned soil samples and global remote sensing reflectance measurements, the rate of space weathering in the lunar regolith is not well understood. To address this, we developed a novel three-dimensional landscape evolution model to simulate the physical processes that control the burial, excavation, and transport of regolith on airless bodies. Applying this model to the lunar mare, we find that over billions of years of surface evolution, material typically spends only a few million years on the surface where it is exposed to the effects of space weathering. The small surface residence times are a result of vigorous mixing by small-scale impacts, predominantly driven by secondary crater formation. We deduce the rate of space weathering by comparing our modeled distribution of surface residence times on the lunar mare to measurements of space weathering maturity from Apollo soil samples and orbital surface reflectance datasets. These chemical constraints indicate that soil on the lunar mare reaches maturity in 7 Myr of cumulative surface exposure though due to uncertainties in the rate of small secondary crater production, this timescale could be 2-3 times higher. Weathering progresses more rapidly upon initial exposure to space but the surface residence time required to achieve maturity is realized over billions of years as regolith is repeatedly buried and exposed by small impacts. Plain Language Summary On the Moon, large impact craters churn the upper soil layers and micrometeorites, galactic cosmic rays, and the solar wind alter the chemical structure of material on the surface in a process called space weathering. The relationship between ...