科研之友
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摘要
We investigate the impact history of the Near Earth Asteroid (NEA) Eros 433 using a new material model for brittle materials such as rocks, where initial flaw distributions within the rock are explicitly defined to match what is known about flaw size distributions in rocks. These simulations are limited to the initial impact phase of the crater formation process and use a very crude approximation for the effect of the gravitational overburden pressure. Given these approximations, our simulations of this numerical approximation of Eros suggest that the current observed bulk porosity of about 25% could be consistent with the porosity generated by the formation of the three largest craters observed on Eros indicating that Eros could have started as an intact shard from a prior impact event. Further, we investigate the consequences of two possible internal flaw distributions for the asteroid: a "strong" flaw distribution with shorter crack lengths, that are more difficult to activate during cratering; and a "weak" flaw distribution with longer flaws. The "strong" distribution produces localized deformation regions (lineaments) that are resolved by the simulations, while the "weak" distribution does not produce resolved localized features. For either distribution of internal flaws the initial impact (assumed to be the Himeros forming impact) shatters but does not disrupt the body implying that simulations of asteroid mitigation approaches should assume that asteroids will behave like rubble piles. Subsequent impact events activate linear features created by prior impacts but only change the orientation of the lineament structure near the impact site.
- 出版日期2016-3-1
