Large Boulders on (21) Lutetia: Implications for Cratering Processes and Internal Structure

During the flyby of Lutetia by the Rosetta spacecraft, the OSIRIS narrow angle camera (NAC) imaged the asteroid with a resolution of up to 60 m/pixel. One of the geological features visible on the close-up images of Lutetia during the flyby of the Rosetta spacecraft is the appearance of numerous large boulders (100s of meters in diameter) on the surface of the asteroid. Those are the largest rock fragments found so far on small bodies in the solar system. They are most likely created by the largest impacts on Lutetia. We will present the number, size distribution and spatial distribution of the boulders. The trajectory of boulders ejected from various craters will be calculated, and, together with scaling laws for impact cratering, will be used to estimate how many boulders have been released by each of the large impacts. This is a direct measure of the high end of the size distribution of ejecta from individual impacts, allowing to test impact scaling relations and to constrain the strength and internal structure of different regions of Lutetia before the impacts.