The azimuthal distribution of ejecta mass from oblique impacts into sand

TL;DR

This study investigates how ejecta mass distribution from oblique impacts into sand varies with azimuthal and impact angles, revealing strong directional dependence and modifying crater scaling laws.

Contribution

It introduces modified crater ejecta scaling laws that incorporate azimuthal and impact angles, based on experimental data.

Findings

Ejecta mass distribution is highly sensitive to azimuthal angle.

Crater radii depend on impact and azimuthal angles.

Ejecta mass can be estimated from the cube of crater radius.

Abstract

We measure ejecta mass as a function of azimuthal and impact angle for 104 m/s oblique impacts into sand. We find that the ejecta mass distribution is strongly sensitive to azimuthal angle with as high as 8 times more mass in ejecta on the downrange side compared to the uprange side. Crater radii, measured from the impact point, are measured at different impact and azimuthal angles. Crater ejecta scaling laws are modified to depend on azimuthal and impact angle. We find that crater radii are sensitive to both impact and azimuthal angle but the ejecta mass as a function of both angles can be estimated from the cube of the crater radius without an additional angular dependent function. The ejecta distributions are relevant for processes that depend upon the integrated properties of approximately 100 m/s impacts occurring in the outer solar system and possibly during planetesimal formation.