Establish destruction and interconversion kinetics in candidate Oxia mineral mixtures

Establish compound-specific destruction and true L↔D interconversion rates for amino acids in candidate Oxia Planum mineral–oxychlorine mixtures under relevant irradiation conditions, in order to determine which laboratory preservation regime applies at Oxia.

Background

The model transfers radiolytic-destruction enhancement factors measured for L-isovaline in fused silica and dry magnesium perchlorate to other amino acids and to Oxia mineralogies. The relevant natural matrices include Fe/Mg phyllosilicates and opal-A, for which equivalent measurements are unavailable.

This uncertainty is decisive because the radiogenic dose is either a small correction or the dominant limitation depending on the matrix enhancement. The paper identifies matrix-resolved destruction and interconversion measurements as the most useful way to determine whether the conditional preservation boundaries apply to actual Oxia samples.

References

Which case applies at Oxia Planum is not established.

— Radiation limits on amino acid preservation and chiral measurement at Oxia Planum  (2610.17931 - Atri, 13 Oct 2026) in Section 6.3, “Mineral-matrix dependence of the radiogenic channel”; see also Section 6.5

The baseline $C_{0,\min}$ values derive from a single kinetic compilation, so the ranking of amino acids by radiation resistance is uncertain. For example, the converted DSC values of \citet{IglesiasGroth2011} give $D_{37}{\mathrm{Asp}=69.5$~MGy and $D_{37}{\mathrm{Ala}=8.55$~MGy, whereas fits to the multi-dose HPLC concentrations of \citet{KminekBada2006} give 6.25 and 8.87~MGy, respectively. The ordering of aspartic acid and alanine therefore reverses between published datasets. Differences in irradiation protocol, observable, fitting, and sample form may explain part of the discrepancy, and the available data do not show which set applies to Oxia Planum.

— Radiation limits on amino acid preservation and chiral measurement at Oxia Planum  (2610.17931 - Atri, 13 Oct 2026) in Section 6.4, “Kinetic-dataset dependence of the ordering of amino acids”

The excited-state estimate suggests that the high laboratory dose rate may have little effect on degradation, although dose-rate dependence in solid amino acids has not, to our knowledge, been tested experimentally.

— Radiation limits on amino acid preservation and chiral measurement at Oxia Planum  (2610.17931 - Atri, 13 Oct 2026) in Section 6.6, “Limitations”