Abstract We explore the aftereffects of stand-off burst mitigation on kilometer-scale rubble pile asteroids. We use a simple model of X-ray energy deposition to calculate the impulse transferred to the target, in particular to burst-facing blocks on the target surface. The impulse allows us to estimate an initial velocity field for the blocks on the outer side of the target facing the burst. We model the dynamics using an N-body polyhedron program built on the Open Dynamics Engine, a “physics engine” that integrates the dynamical equations for objects of general shapes and includes collision detection, friction, and dissipation. We tested several different models for target objects: rubble piles with different mass distributions, a “brick-pile” made of closely fitting blocks and zero void space, and a non-spherical “contact binary” rubble pile. Objects were bound together by self-gravity and friction/inelastic restitution with no other cohesive forces. Our fiducial cases involved objects of m=3.5×1012 kg (corresponding to a radius of 0.7km for the bulk object), an X-ray yield of 1megaton, and stand-off burst distances of R=0.8–2.5km from the target center of mass. Kilometer-scale rubble piles are robust to stand-off bursts of a yield ( megaton) that would be sufficient to provide an effective velocity change (). Disaggregation involving some tens of percent of the target mass happens immediately after the impulse; the bulk of the object re-accretes on a few gravitational timescales, and the final deflected target contains over 95% (typically, 98–99%) of the original mass. Off-center components of the mitigation impulse and the target mass distribution cause a small amount of induced spin and off-axis components of velocity change. The off-axis velocity component amounts to an angular deviation of 0.05–0.1 radians from the nominal impulse vector, which may be important for mitigation planning.
Highlights ► We model the response of km-scale asteroids to x-ray stand-off bursts. ► Rubble-pile asteroids are robustly resistant to disruption by megaton bursts. ► Internal structure may cause significant off-axis velocity changes.
Effects of stand-off bursts on rubble-pile targets: Evaluation of a hazardous asteroid mitigation strategy
Acta Astronautica ; 73 ; 10-22
2011-10-26
13 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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