Seismic wave experiments in granular media with applications to asteroids

Abstract

Observational data support the view of asteroids as granular systems. Characterizing their mechanical properties is crucial for space mission planning, assessing Earth’s impact risks, and understanding solar system origins. In this context, we present a laboratory-scale experiment aimed at examining wave propagation in granular media. Our findings demonstrate that the propagation of observed waves at 500 Hz shows significant attenuation with an estimated value of $\alpha =(1.8\pm 0.2)$ Np/m. Additionally, we observe an increase in wave speed with confining pressure, which follows a dependency on $p^{1/2}$, interpreted as mesoscopic nonlinear elasticity. This indicates that a confined granular medium behaves as a nonlinear consolidated medium. Furthermore, we establish the equivalence of propagation properties between impact and vibration by supporting our experimental data analysis with numerical simulations. Applying our findings to model wave propagation in a low-gravity setting involving Dimorphos’ mass and geometry, our laboratory-based approach offers a cost-effective alternative to in situ measurements.