Where should we impact an asteroid to effectively deflect its orbit?


Where should we impact an asteroid to effectively deflect its orbit?

Optimal impact location and orientation for the near-spherical Bennu and the elongated asteroid Itokawa. In general, yellow areas are preferred to deviate from an asteroid rather than green. Credit: Tsinghua University

Recently, NASA’s Double Asteroid Redirection Test (DART) spacecraft slammed into the 170-meter asteroid Dimorphos at 6.6 km/s, as the first on-orbit demonstration of an asteroid deflected by kinetic impact. The DART spacecraft is set to impact the center of Dimorphos almost head-on. Ground-based telescopes have now confirmed that the impact managed to shift the orbital period of Dimorphos by 32 minutes, much more than expected.


But, where should we impact an asteroid to deflect its orbit most effectively? Simply toward the center of the asteroid? These questions have not yet been well investigated.

In a new paper published in Steering, Control and Dynamics Journalresearchers from Tsinghua University proposed an optimized motor impact engineering to improve the effective magnitude of the motor impact deviation, which should advance our understanding of how to take full advantage of the kinetic stimulus and get the best results. They found that a well-designed off-center effect appeared to increase deflection efficiency by more than 50% compared to the central effect used by the DART task.

Their work shows a surprising result that regardless of the shape of the target asteroid or the location/direction in which it will collide, the asteroid’s velocity change always falls on a unique hoodograph, which is determined solely by the asteroid’s physical properties. They call it the delta-v hodograph.

“The Delta-v hodograph is actually a distortion of a perfect spherical surface. Determining a realistic profile requires measuring the influence of impact angles on momentum transfer efficiencies, which can be calculated from hydrodynamic simulations of oblique impacts,” the researchers explained. .

with Numerical simulationA unique hodograph is obtained and applied to optimize the impact location or direction, taking into account both the orbital geometry and the shapes of the asteroids. For near-spherical asteroids like Bennu, the required thrust is sensitive to impact sites, and the optimal impact geometry deviates from normal centripetal impact to the leading side in some orbital geometries, especially for larger orbital angles.

Effective deflection is increased by up to 50% when striking the optimal location compared to a simple centered impact.

For elongated Itokawa-like asteroids, the direction of impact determines the distribution of the delta-v group on the hodograph, and thus the optimal rotational phase of the impact. The preferred direction can increase the final deflection distance by 100% compared to the unfavorable direction value.

“This work presents a simple and innovative application of Delta-v hodograph for optimal geometry in PHA kinetic anomalies, as a link to hypervelocity forcing and long-term orbital dynamics,” the researchers said. “The proposed optimization method should be considered in global trajectory design for future asteroid deflection missions, as the expected deflection distance is determined not only by orbital geometry but also by impact.” Engineering. ”

more information:
Yifei Jiao et al, Optimal Engineering of the Kinetic Impact of Asteroid Deflection Exploiting the Delta-V Hodograph, Steering, Control and Dynamics Journal (2022). DOI: 10.2514/1.G006876

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Tsinghua University

the quoteWhere should we impact an asteroid to effectively deflect its orbit? (2022, November 17) Retrieved November 18, 2022 from https://phys.org/news/2022-11-impact-asteroid-effectively-deflect-orbit.html

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