Asteroid 2024 YR4 was recently making headlines with its rising impact probability for a possible impact in 2032. Astronomers later confirmed that the threat of impact was over as they refined calculations to predict a more accurate trajectory.
Although the asteroid’s impact risk is now negligible, it did trigger planetary defense protocols early into February with its rising impact probability.
The two studies published in Nature Communications explore how planetary defense procedures can be more effective based on observations of the ejecta produced by NASA’s DART impact on asteroid Dimorphos.
The first study, led by Professor Fabio Ferrari in collaboration with Professor Masatoshi Hirabayashi of the Georgia Institute of Technology, focused on the dynamics and morphology of ejecta produced by the DART impact on the asteroid Dimorphos.
The study, titled “Morphology of Ejecta Features from the Impact on Asteroid Dimorphos,” analyzed the behavior of high-speed fragments ejected from the DART impact site on Dimorphos.
It aimed to understand the dynamics and morphology of ejecta produced by NASA’s DART mission, focusing on how ejecta behave in binary asteroid systems under influences such as solar radiation pressure and gravitational forces.
It found that the DART impact on Dimorphos produced ejecta with a mass ranging from 1.1 to 5.5 × 107 kg. Simulations aligned with these estimates and provided detailed visualizations of the ejecta’s behavior post-impact.
The study observed complex interactions between the ejecta, the binary system’s gravity, and solar radiation pressure. Particles forming a tail and those spiraling within the system displayed distinct behaviors depending on size and initial velocity. While some particles re-accreted onto Dimorphos, others traveled farther due to solar radiation influence.
It was discovered that the ejecta behavior at the impact site on Dimorphos is highly dependent on the asteroid’s shape. It determined that the rounded surface of Dimorphos reduced the deflection force by 56% compared to an impact on a completely flat surface.
The second study, led by Professor Hirabayashi, found that kinetic deflection efficiency decreases when impacting smaller near-Earth objects (NEOs) due to their greater curvature.
The study titled “Elliptical ejecta of asteroid Dimorphos is due to its surface curvature” confirmed that an asteroid’s curvature significantly affects the elliptical ejecta plume generated by DART’s impact, reducing momentum transfer efficiency.
The momentum transfer was measured at 44 ± 10% along the orbit track, compared to an equivalent impact on a flat surface.
This suggests that deploying a large deflector does not necessarily result in a more significant push. A more effective approach may involve using multiple smaller impactors instead of a single large one.
Multiple smaller impactors could mitigate the effects of an asteroid’s curvature, making the overall deflection more efficient than a single large impact.
“We used images from the Hubble Space Telescope and numerical simulations to analyze ejecta evolution, successfully estimating the mass, velocity, and size of the ejected particles,” said Professor Ferrari.
“Sending multiple smaller impactors not only results in a higher asteroid push but also potentially saves operational cost and increases tactical flexibility for deflection,” stated Masatoshi Hirabayashi.
The findings from both studies offer important insights into the effects of deflector impacts on asteroids, contributing to the development of cost-effective and tactically flexible planetary defense strategies. Additionally, they provide information on asteroid composition and its influence on deflection outcomes.
References:
1 Morphology of ejecta features from the impact on asteroid Dimorphos – Fabio Ferrari et al – Nature Communication – February 14, 2025 –
2 Elliptical ejecta of asteroid Dimorphos is due to its surface curvature – Masatoshi Hirabayashi et al. -Nature Communication – February 14, 2025 –