Proximal boulders and momentum transfer from DART-scale 3D impact simulations on asteroid Dimorphos
Bibliographic record
Abstract
ABSTRACT The NASA Double Asteroid Redirection Test (DART) mission successfully changed the trajectory of asteroid Dimorphos by hypervelocity kinetic impact. The spacecraft imaged a boulder-strewn surface, yet the asteroid’s internal structure remains unknown. To understand how boulders surrounding the impact point influence ejecta and momentum transfer, 3D impact simulations were performed using the isale shock physics code, varying the number, size, burial depth, and radial distance of proximal boulders. Results show that boulders positioned off-centre, adjacent to the impact site, can locally suppress or redirect ejecta, producing peripheral effects on the momentum enhancement factor, $\beta$, with net variations within 8 per cent compared to the no-boulder case. These effects are confined to a radial zone extending up to around 10 meters (around 16 impactor radii) from the impact point, within which proximal boulders can efficiently govern ejecta and momentum transfer. Outside this zone, the influence of boulders on deflection efficiency becomes negligible. This underscores the limited influence of boulders surrounding the impact site and points to the dominant role of those within the projectile-target coupling zone, offering insights for planetary defense applications. To probe impact ejecta over extended time-scales, axisymmetric 2D simulations were conducted with a mass-strength rescaling that conserves boulder mass density and strength per boulder ‘ring’. This reproduces $\beta$ trends in 3D while enabling longer 2D simulations of boulder-rich rubble-pile targets in spheroidal volumes. Simulated $\beta$ values remain close to the observed range, suggesting plausible interior solutions for Dimorphos and supporting efforts to probe its interior ahead of ESA’s Hera mission.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".