3:30 PM - 3:45 PM
[MZZ40-07] Investigations of the effects of target strength and interior structure on momentum transfer by a kinetic impactor
Keywords:Planetary Defense, 1994 YR4, Impact Experiments, Kinetic Impactor
Spacecraft observations and theoretical models indicate that asteroids likely have a range of internal structures. Many potential hazardous asteroids, such as the recently discovered 2024 YR4, are small and could be coherent boulders. Impacts on to objects of this size are thought to be controlled by the strength of the asteroids, rather than their extremely low gravity. Impact outcomes on strength-controlled objects are highly sensitive to their interior structures, which are poorly constrained. In order to formulate an appropriate mitigation strategy for such objects, it is important to understand what deflection outcomes are likely given different plausible interior structures. We undertook a set of laboratory experiments into well characterized targets with different strengths and interior structures to assess the influence of these parameters on the efficiency of a kinetic impactor’s momentum transfer.
Here, we report on two sets of experiments undertaken at the JHUAPL Impact Lab and the Ames Vertical Gun Range. We considered impact velocities ranging from 0.15 to 2.5 km/s. We fired either ¼” Alumina projectiles (<0.5 km/s) or pyrex sphere (<2km/s) into near-spherical targets of varying strength and internal structure that we fabricated using powder mixtures. The targets have well characterized porosity and strength properties; variations in their interior are understood using X-ray computed tomography (XCT) scans. We prepared both small (6cm) and large (10cm) targets.
During each experiment, we use two high speed (>1000frames/s) cameras to measure the impact location and angle of the projectile, and directly measure the linear and angular displacement of the target as it swings like a pendulum following impact. The displacements provide estimates of the velocity changes experienced by the target, and its post-impact momentum. We then estimate the fraction of the momentum imparted by the projectile to the target. We also measure the ejection speed and direction of target ejecta, to understand the origin of any momentum enhancement, and characterize the shape and mass of the largest individual ejecta excavated during each impact.
At the time writing, we have completed more than 40 successful shots. In this presentation, we will provide a quantitative assessment of our findings, establishing the connection between asteroid interior structure and the impact momentum enhancement factor for both our low-speed (<0.5 km/s) and high speed-impacts (<2.5 km/s).
Here, we report on two sets of experiments undertaken at the JHUAPL Impact Lab and the Ames Vertical Gun Range. We considered impact velocities ranging from 0.15 to 2.5 km/s. We fired either ¼” Alumina projectiles (<0.5 km/s) or pyrex sphere (<2km/s) into near-spherical targets of varying strength and internal structure that we fabricated using powder mixtures. The targets have well characterized porosity and strength properties; variations in their interior are understood using X-ray computed tomography (XCT) scans. We prepared both small (6cm) and large (10cm) targets.
During each experiment, we use two high speed (>1000frames/s) cameras to measure the impact location and angle of the projectile, and directly measure the linear and angular displacement of the target as it swings like a pendulum following impact. The displacements provide estimates of the velocity changes experienced by the target, and its post-impact momentum. We then estimate the fraction of the momentum imparted by the projectile to the target. We also measure the ejection speed and direction of target ejecta, to understand the origin of any momentum enhancement, and characterize the shape and mass of the largest individual ejecta excavated during each impact.
At the time writing, we have completed more than 40 successful shots. In this presentation, we will provide a quantitative assessment of our findings, establishing the connection between asteroid interior structure and the impact momentum enhancement factor for both our low-speed (<0.5 km/s) and high speed-impacts (<2.5 km/s).