Cometary dust analogues for physics experiments

TL;DR

This paper develops and characterizes a dust analogue mimicking cometary non-volatile materials, enabling earth-based experiments to study comet physics under controlled conditions.

Contribution

It introduces a new mixture of silica dust and charcoal as a physical analogue for cometary dust, validated by multiple property measurements.

Findings

Optimal analogue mixture is 60-70% silica dust and 30-40% charcoal.

The analogue matches key physical properties of cometary dust.

This analogue will be used in future comet physics experiments.

Abstract

The CoPhyLab (Cometary Physics Laboratory) project is designed to study the physics of comets through a series of earth-based experiments. For these experiments, a dust analogue was created with physical properties comparable to those of the non-volatile dust found on comets. This "CoPhyLab dust" is planned to be mixed with water and CO$_2$ ice and placed under cometary conditions in vacuum chambers to study the physical processes taking place on the nuclei of comets. In order to develop this dust analogue, we mixed two components representative for the non-volatile materials present in cometary nuclei. We chose silica dust as representative for the mineral phase and charcoal for the organic phase, which also acts as a darkening agent. In this paper, we provide an overview of known cometary analogues before presenting measurements of eight physical properties of different mixtures of the two materials and a comparison of these measurements with known cometary values. The physical properties of interest are: particle size, density, gas permeability, spectrophotometry, mechanical, thermal and electrical properties. We found that the analogue dust that matches the highest number of physical properties of cometary materials consists of a mixture of either 60\%/40\% or 70\%/30\% of silica dust/charcoal by mass. These best-fit dust analogue will be used in future CoPhyLab experiments.