Oblique incidence hypervelocity impacts on rock

摘要: The behaviour of granite rock under normal incidence hypervelocity impact in the laboratory has been studied using impacts 2-mm diameter stainless-steel spheres at between 1 and 6 km s(-1). It was found that, incidence, there is a strong dependence crater size with speed (v). Crater mass to depend on v((2.3+/-0.4)), i.e. compatible scaling energy. However, depth have different dissimilar dependences speed, such that shape (depth/diameter) not constant, but decreases as increases, being 0.26 s(-1) falling linearly 0.16 In addition, second data set same projectile target combination taken mean 5.4 +/- 0.2 s(-1), angle ranging from 0degrees (normal incidence) 85degrees (glancing incidence). oblique show excavated start decrease immediately when non-normal occurs. length width initially slower rate, little apparent until exceeds 50degrees normal. At highest angles (85degrees, glancing incidence), sudden change shape, no longer decreasing increases. for impacts, scales cos theta square costheta indicated earlier work. This similar observed other brittle ductile materials. Finally, used predict populations non-circular craters large Solar system bodies, results yield estimates (3 per cent) close rate (5 Venus, Mars Moon.