An artificial impact on the asteroid 162173 Ryugu formed a crater in the gravity-dominated regime

The Hayabusa2 spacecraft investigated the small asteroid Ryugu, which has a rubble pile structure. We describe an impact experiment on Ryugu using Hayabusa2’s Small Carry-on Impactor (SCI). The impact produced an artificial crater with a diameter >10 m, which has a semicircular shape, an elevated rim and a central pit. Images of the impact and resulting ejecta were recorded by the Deployable CAMera 3 (DCAM3) for >8 min, showing the growth of an ejecta curtain (the outer edge of the ejecta) and deposition of ejecta onto the surface. The ejecta curtain was asymmetric, heterogeneous, and never fully detached from the surface. The crater formed in the gravity-dominated regime i.e., crater growth was limited by gravity, not surface strength. We discuss implications for Ryugu’s surface age.