Asteroids' Oddball Shapes Make Deflecting Them Challenging

Asteroids in the asteroid belt vary in shape and composition, making it challenging to predict their behavior when they approach Earth. NASA’s DART mission used a kinetic impactor to deflect Dimorphos, but the more critical issue is dealing with asteroids that are not discovered in time for a kinetic impactor to effectively change their trajectory. Researchers have explored using nuclear weapons to generate radiation pulses that could deflect asteroids, but irregular shapes complicate modeling. The new algorithm developed by Nathan Moore at Sandia National Laboratories allows for efficient computation of vapor ejecta over asteroid geometries, significantly improving deflection predictions. The algorithm is over 1,600 times faster, enabling accurate simulations of asteroids with irregular shapes. The simulation predicts deflection of three asteroids—Bennu, Itokawa, and Golevka—from both near and far-field irradiations, showing how the orientation of the asteroid affects deflection velocity. The results highlight the importance of asteroid shape in determining deflection effectiveness. The simulation can be applied to any mapped asteroid, allowing for calculations of explosion size, distance, and surface exposure. The model accounts for vaporization, which is the main factor in deflection, but it cannot predict the full breakup of the asteroid body. The study shows that the orientation of the asteroid at the time of intercept can increase deflection velocity by up to five times for certain asteroids. The research underscores the critical role of asteroid shape in deflection strategies and the need for high-resolution topographic data to improve accuracy. The findings suggest that placing nuclear weapons in space could be a viable option for asteroid deflection, though it remains a complex and geopolitically sensitive task.

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