Scale effects in strength-dominated collisions of rocky asteroids

Citation
Kr. Housen et Ka. Holsapple, Scale effects in strength-dominated collisions of rocky asteroids, ICARUS, 142(1), 1999, pp. 21-33
Citations number
33
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
ICARUS
ISSN journal
0019-1035 → ACNP
Volume
142
Issue
1
Year of publication
1999
Pages
21 - 33
Database
ISI
SICI code
0019-1035(199911)142:1<21:SEISCO>2.0.ZU;2-2
Abstract
The application of laboratory collision experimental results to the larger scales of asteroid impacts is complicated by the fact that the dynamic stre ngth of rock typically decreases as the loading duration increases. Because loading times increase with the size scale of a collision, large bodies ar e effectively weaker than small ones. While this effect has been postulated for over a decade, it has never been verified in actual collision experime nts. This paper summarizes collision tests performed under the conditions r equired to examine scale effects, i.e., increasing the size scale of the ex periment while holding the impact velocity and impact kinetic energy per ta rget mass constant. Granite targets are used, with a diameter variation of a factor of 18, The larger targets experienced significantly more collisional damage than small ones, confirming a decrease in dynamic strength with increasing size scale . The results are compared to a scaling model based on the concept that fragm entation is accomplished through the growth and coalescence of preexisting flaws. Measurements of the actual flaw-size distribution are used to valida te the model. Field observations of flaw and fault sizes at scales to 10 km are used to construct a scaling model that is believed to apply to the sha ttering of a wide range of rock types. The results show that kilometer-size d rocky bodies may be significantly weaker than indicated by previous estim ates, (C) 1999 Academic Press.