A Harmonized Lunar Boulder Database Across 46 Study Regions: Size Distributions, Geomorphic Context, and Surface-Exposure Metrics

This repository provides a provenance-preserving database of lunar boulder measurements harmonized from seven source datasets and 46 study regions across the lunar nearside and farside. The regions encompass impact craters and ejecta, crater walls, slopes and rockfall settings, mare and highland terrains, tectonic and volcanic landforms, and the Apollo 17 Taurus–Littrow Valley. The archive contains 108,853 standardized records. After quality control and conservative duplicate screening, 108,704 unique valid boulder records were retained. Available attributes include study-region and source provenance, LROC image identifiers, geographic or local coordinates, boulder diameter, projected area, diameter definition, mapped area, and quality-control status. Region-specific operational lower thresholds were estimated from turnovers in log-binned diameter distributions. Power-law and shifted-exponential models were fitted to identical unbinned observations above these thresholds. The repository includes fitted parameters, bootstrap confidence intervals, AICc and KS statistics, model rankings, threshold diagnostics, figure-source data, and reproducible Python code. Formal model comparison was conducted for 26 regions containing at least 100 boulders above their operational thresholds. For six reliable regions with complete mapped areas, threshold-dependent number density, projected-area fraction, and standardized 100 m²-footprint encounter probability are provided. Coordinate-resolved spatial-exposure data are also included for North Ray. The operational thresholds are empirical fitting limits rather than independently validated detection-completeness thresholds. Because the source datasets differ in image properties, mapping procedures, diameter definitions, and spatial coverage, the exposure indicators should be interpreted as comparative scientific measures rather than engineering-certified landing-risk estimates.