Multiscale Characterization of an Ordinary Chondrite Reveals Scale-Dependent Properties and Pore-Controlled Fragmentation

Meteorites are samples of asteroids, making their mechanical characterization necessary for developing planetary defense, in situ resource utilization, and mission design strategies. Many ordinary chondrites, the most common meteorites on Earth, contain fine-grained clastic textures composed of weakly bound mineral fragments. Here, we show that these ordinary chondrites behave mechanically as weakly consolidated granular materials. We applied microstructural characterization, multiscale indentation, friability testing, and He pycnometry to Zhob (H3-4), a representative ordinary chondrite dominated by a clastic matrix supporting chondrules, metal, and sulfides within a pervasive network of pores, grain boundaries, and fractures. Nanoindentation reveals grain-scale mechanical heterogeneity, whereas microindentation yields lower, more uniform values due to a larger indentation footprint, which averages across multiple grains and intervening pore spaces. The pycnometry yields a porosity in the upper range of H chondrite falls. Friability experiments combined with pore-length distribution analysis show that fragmentation preferentially follows pre-existing weak interfaces rather than fracturing intact grains, producing fragment sizes consistent with in situ grain sizes. These results indicate that microscale mechanical behavior is governed by weak intergranular bonding rather than by the strength of individual grains. This implies that structurally similar S-type asteroid materials are mechanically weak, prone to low-energy disaggregation, and likely to generate fine debris during excavation alongside intact chondrules and metal grains.