Approximately 65 million years ago, an asteroid hypothesized to have an initial speed of ～20km/s and a diameter of ～10km struck the ocean near what is present-day Chicxulub, Yucatan, Mexico. The inference of the asteroid's initial velocity, size, shape, and material properties from geological evidence is problematic because the evolution of such a system might not produce discriminating diagnostics from distinct initial states. Considered as an inverse problem, moreover, the problem is poorly constrained. Here I use an adaptive-mesh Eulerian hydrodynamic code, integrated with a Mie-Gruneisen strength-of-materials package and a simple material-failure criterion, to analyze the sensitivity of maximum crater depth and maximum crater diameter to asteroid initial density (3.3g/cc (dunite) vs. 7.9g/cc (Fe-Ni)), assuming Chicxulub-like ocean, crust, and mantle structures. The results show that maximum crater diameter is a poor, but that maximum crater depth is a good, diagnostic of plausible initial densities under these constraints. Taken in conjunction with the results of earlier studies, these observations further suggest that maximum crater diameter and depth are largely insensitive to a wide range of plausible crust structures.
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