The Moon possesses two distinct hemispheres, both of which have undergone space weathering, yet its role on the farside and differences from the nearside remain debated. Here, we present high-precision iron (Fe) and potassium (K) isotopic analyses of lunar soils returned by the Chang’e-6 (CE6) mission. The CE6 bulk and three sieved soils exhibit heavier Fe and K isotopic compositions than the lunar mantle (δ56Fe = 0.18 ± 0.02‰ to 0.30 ± 0.02‰; δ41K = 2.10 ± 0.04‰ to 4.67 ± 0.04‰). Such heavy isotopic signatures cannot be explained by the initial soil compositions, meteoritic input, or cosmic–ray effects. Instead, the observed positive correlations of Fe and K isotopes with both particle size and chemical composition indicate the dominant role of space weathering, particularly micrometeoroid impact processes. The heavy Fe and K isotopes indicate a mature nature for the CE6 samples. Based on Ne isotopes, the cosmic-ray exposure age of the CE6 soils is ∼ 146 Myr, longer than that of the Chang’e-5 (CE5) soils. Compared to CE5 soils from the nearside at similar latitudes, CE6 soils exhibit heavier Fe isotopic compositions, which can be best explained by their longer exposure history in conjunction with the presence of ancient regolith components formed between 2.8 and 2.0 Ga. Therefore, our results, combined with Si isotopes, suggest that the impact flux at the two landing sites have likely not differed since 2.8 Ga.
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