Location of upper borders of cavities containing dust and gas under pressure in comets

TL;DR

This paper estimates the depth of cavities containing dust and gas under pressure in comet Tempel 1, suggesting such features are common just beneath the surface, based on impact crater data.

Contribution

It provides the first estimates of the upper borders of cavities under pressure in comets using impact crater analysis.

Findings

Cavities are approximately 4-6 meters below the surface.

Cavities containing dust and gas are likely common in comets.

Depth estimates depend on impact crater size.

Abstract

The distance between the pre-impact surface of Comet 9P/Tempel 1 and the upper border of the largest cavity excavated during ejection of material after the collision of the impact module of the Deep Impact spacecraft with the comet is estimated to be about 5-6 metres if the diameter of the DI transient crater was about 150-200 m. The estimated distance was 4 m at the diameter was 100 m. This result suggests that cavities containing dust and gas under pressure located a few metres below surfaces of comets can be frequent.