The current work explores the interactions between asteroid fragments and the associated flow topology to motivate a physically consistent representation of the fragmentation process following a fragmentation event during atmospheric entry. Multibody aerodynamic simulations run with computational fluid dynamics (CFD) solvers were used to generate a lookup table of forces detailing the interactions of two spheres. Trajectory simulations parsing the resulting database to determine the relative motions of any two spherical fragments were then validated with hypersonic wind tunnel experiments. A following series of fragment interaction simulations yielded categorization of the fragments' final relative states and an estimate of the total time of interaction. The fragment interaction model was nondimensionalized to permit study over a wide range of possible asteroid impacts. The interaction parameters are presented with explicit semi-analytic equations, defining the asteroid fragment-flow interaction model and thereby eliminating the need to perform a separate fragment interaction simulation for each fragmentation event in an atmospheric entry model. Finally, a set of illustrative examples demonstrates the efficacy of the model in a variety of fragmentation situations.
Bibliographical noteFunding Information:
This work was partially funded by NASA's Planetary Defense Coordination Office (PDCO). Super computing resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at NASA Ames Research Center. Images in Figs. 24–25 were produced by D.K. Robertson (Science and Technology Corporation, NASA Ames Research Center). The authors would also like to thank D.K. Robertson, L.F. Wheeler, J.L. Dotson, and R.S. Longenbaugh for their comprehensive reviews and constructive feedback during the revision process, as well as C.M. Rumpf for many helpful suggestions regarding the presentation of the work.
© 2019 The Authors
- Asteroid dynamics
- Near-earth objects