Simulations of the Pre- and Post-impact System Dynamics of the DART Mission Target Binary Asteroid 65803 Didymos
Abstract
As part of the AIDA cooperation, NASA's Double Asteroid Redirection Test (DART) is designed to be the first demonstration of a kinetic impactor for planetary defense against a small body impact hazard. The target is binary asteroid 65803 Didymos. Here we report on investigations by the AIDA Dynamical and Physical Properties working group aimed at characterizing the Didymos system's pre-impact dynamics and modeling changes that may be induced by the DART spacecraft's impact with the secondary during the system's October 2022 close approach to Earth. We have conducted high-fidelity Full Two-Body Problem (F2BP) simulations of the system dynamics over time frames appropriate to the mission duration, including planned post-impact ground-based observation. Example results show the expected modes of motion given full coupling between primary and secondary body rotation and binary orbit (e.g., spin-orbit co precession, secondary libration). These modes are all expected to be as relaxed as possible pre-impact. As part of this study, we conducted a broader F2BP simulation benchmarking exercise. This used four test systems and involved participants with various numerical integrators and force and torque models based on different mutual potential formulations (e.g., higher-order inertia integrals, packed cubes/spheres). We compared metrics of computational cost and accuracy/precision loss with respect to conserved quantities and differential geometric properties of the underlying dynamics, to inform selection of the best simulation methodologies for different contexts. We also examined potential effects of the DART impact on the dynamics, which is nominally expected to reduce the binary orbit period by a few minutes. A key uncertainty is the kinetic impactor momentum transfer enhancement parameter, beta, which partly depends on the targeting dispersion about the nominal (optimal) impact location. In light of this, we have tested a range of beta values and impact locations, and performed F2BP simulation of the post-impact dynamics in each case. This has allowed determination of which dynamical modes are excited and by how much, with particular focus on induced libration amplitudes. It has also bounded the probability of breaking on-average synchronous rotation of the secondary.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.P51A..04R
- Keywords:
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- 4314 Mathematical and computer modeling;
- NATURAL HAZARDSDE: 4316 Physical modeling;
- NATURAL HAZARDSDE: 6022 Impact phenomena;
- PLANETARY SCIENCES: COMETS AND SMALL BODIESDE: 6035 Orbital and rotational dynamics;
- PLANETARY SCIENCES: COMETS AND SMALL BODIES