The specific heat of astro-materials: Review of theoretical concepts, materials and techniques

TL;DR

This review paper discusses theoretical concepts, materials, and techniques related to the specific heat of astro-materials, providing models, data, and methods for estimating heat capacities of minerals and solar system materials across a wide temperature range.

Contribution

It introduces a comprehensive database and a mixing model for calculating specific heat of minerals and astro-materials, enabling temperature extrapolation and application to various solar system substances.

Findings

Developed a database of mineral heat capacities from literature.

Created a model to estimate specific heat for various astro-materials.

Provided example cp(T) curves for meteorites, ices, and tholins.

Abstract

We provide detailed background, theoretical and practical, on the specific heat cp of minerals and mixtures thereof, 'astro-materials', as well as background information on common minerals and other relevant solid substances found on the surfaces of solar system bodies. Furthermore, we demonstrate how to use specific heat and composition data for lunar samples and meteorites as well as a new database of endmember mineral heat capacities (the result of an extensive literature review) to construct reference models for the isobaric specific heat cP as a function of temperature for common solar system materials. Using a (generally linear) mixing model for the specific heat of minerals allows extrapolation of the available data to very low and very high temperatures, such that models cover the temperature range between 10 and 1000 K at least (and pressures from zero up to several kbars). We describe a procedure to estimate cp(T) for virtually any solid solar system material with a known mineral composition, e.g., model specific heat as a function of temperature for a number of typical meteorite classes with known mineralogical compositions. We present, as examples, the cp(T) curves of a number of well-described laboratory regolith analogues, as well as for planetary ices and 'tholins' in the outer solar system. Part II will review and present the heat capacity database for minerals and compounds and part III is going to cover applications, standard reference compositions, cp(T) curves and a comparison with new and literature experimental data.