The log-logistic evolution of meteorite friability and implications for asteroid regolith

Friability of meteorites, the tendency to crumble under repeated low stresses, influences the collisional and geological evolution of asteroids and small planetary bodies. Here, we quantify meteorite friability through laboratory tumbling experiments on a broad range of stony near-Earth objects. Disaggregation follows a bounded multiplicative process: it first accelerates with cumulative impacts, then slows as breakable material is exhausted. A log-logistic model describes this behavior and captures a material-dependent limit due to the “pillow-effect,” where accumulating fine debris cushions further impacts. The number of rotations needed for complete disaggregation varies by more than six orders of magnitude, indicating much broader timescales for regolith maturation and rubble-pile evolution than previously assumed. Fine dust generated from friable materials may also enhance cohesion under microgravity, helping explain the weak yet cohesive surfaces of rubble-pile asteroids such as Bennu and Ryugu. These measurements provide a framework for quantitatively incorporating friability into asteroid evolution models. Asteroid regolith maturation and rubble-pile evolution occur over comparably broad timescales, according to foundational friability measurements derived from mechanical tumbling experiments conducted on a broad range of meteorite types