Alignment of fractures on Bennu’s boulders indicative of rapid asteroid surface evolution

On asteroids, fractures develop due to stresses driven by diurnal temperature variations at spatial scales ranging from sub-millimetres metres. However, the timescales of such rock fracturing thermal fatigue are poorly constrained observations. Here we analyse images asteroid (101955) Bennu obtained Origins, Spectral Interpretation, Resource Identification and Security-Regolith Explorer (OSIRIS-REx) mission show that metre-scale on boulders exposed surface have a preferential meridional orientation, consistent with cracking induced variations. Using an analytical model fracture propagation, suggest length those Bennu’s can be produced in 104–105 years. This is comparable or shorter timescale than mass movement processes act expose fresh surfaces reorient any direction signature. We propose boulder happens rapidly compared lifetime near-Earth space other carbonaceous asteroids. The damage this space-weathering process has consequences for material properties these implications preservation primordial signature acquired during accretional phases protoplanetary disk our solar system. Fractures imaged OSIRIS-REx spacecraft over geologically rapid timescales.