Martin Jutzi^a and Patrick Michel^b

^aUniversity of Bern, Center for Space and Habitablity, Physics Institute, Sidlerstrasse 5, 3012 Bern, Switzerland
^bLagrange Laboratory, University of Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, B.P. 4229, 06304 Nice Cedex 4, France

In this paper, we investigate numerically the momentum transferred by impacts of small (artificial) projectiles on asteroids. The study of the momentum transfer efficiency as a function of impact conditions and of the internal structure of an asteroid is crucial for performance assessment of the kinetic impactor concept of deflecting an asteroid from its trajectory. The momentum transfer is characterized by the so-called momentum multiplication factor β, which has been been introduced to define the momentum imparted to an asteroid in terms of the momentum of the impactor. Here we present results of code calculations of the βfactor for porous targets, in which porosity takes the form of microporosity and/or macroporosity. The results of our study using a large range of impact conditions indicate that the momentum multiplication factor β is small for porous targets even for very high impact velocities (β<2 for v_imp≤15 km/s), which is consistent with published scaling laws and results of laboratory experiments (Holsapple and Housen, 2012 and Holsapple and Housen, 2013). It is found that both porosity and strength can have a large effect on the amount of transferred momentum and on the scaling of β with impact velocity. On the other hand, the macroporous inhomogeneities considered here do not have a significant effect on β.

Reference
Jutzi M and Michel P (in press) Hypervelocity impacts on asteroids and momentum transfer I. Numerical simulations using porous targets. Icarus
[doi:10.1016/j.icarus.2013.11.020]
Copyright Elsevier

Link to Article