Fragment shapes in impact experiments ranging from cratering to catastrophic disruption

• DOI: 10.1016/j.icarus.2015.09.038
• Publication Date: 2015-10-18T03:54:15Z
• Authors: Tatsuhiro Michikami; Axel Hagermann; Tokiyuki Kadokawa; Akifumi Yoshida; Akira Shimada; Sunao Hasegawa; Akira Tsuchiyama
• Keywords: Impact energy

Laboratory impact experiments have found that fragments tend to be elongated. Their shapes, as defined by axes a, b and c, these being the maximum dimensions of fragment in three mutually orthogonal planes (a ⩾ c), are distributed around mean values axial ratios b/a ∼ 0.7 c/a 0.5. This corresponds a:b:c simple proportion 2:√2:1. The shape distributions some boulders on Asteroid Eros, small- fast-rotating asteroids (diameter <200 m rotation period <1 h), young families, similar those laboratory created catastrophic disruptions. Catastrophic disruption is, however, a process is different from cratering. In order systematically investigate shapes range cratering disruption, for basalt targets 5–15 cm size were performed. A total 28 carried out firing spherical nylon projectile 7.14 mm) perpendicularly into target surface at velocities 1.60–7.13 km/s. More than 12,700 with 4 mm generated measured. We value each decreases decreasing energy per unit mass. For instance, an event nearly 0.2, which considerably smaller (∼0.5). data presented here can provide important evidence interpret asteroid surfaces, constrain current interpretations formation. As example, applying our experimental results boulder Itokawa's surface, we infer parent body must experienced disruption.