Glycine's Radiolytic Destruction in Ices: First In-Situ Laboratory Measurements for Mars

TL;DR

This study provides the first in-situ laboratory measurements of glycine's radiolytic destruction in ices under conditions similar to Mars, estimating its half-life and decay trends relevant for Martian surface chemistry.

Contribution

It introduces new laboratory data on glycine decay rates in ices across a range of temperatures and compositions, enabling better extrapolation to Martian conditions.

Findings

Glycine decay rates increase with temperature.

Half-life of glycine on Mars is estimated based on laboratory data.

Decay trends vary with ice composition and temperature.

Abstract

We report new laboratory studies of the radiation-induced destruction of glycine-containing ices for a range of temperatures and compositions that allow extrapolation to Martian conditions. In-situ infrared spectroscopy was used to study glycine decay rates as a function of temperature (from 15 to 280 K) and initial glycine concentrations in six mixtures whose compositions ranged from dry glycine to H$_2$O + glycine (300:1). Results are presented in several systems of units, with cautions concerning their use. The half-life of glycine under the surface of Mars is estimated as an extrapolation of this data set to Martian conditions, and trends in decay rates are described as are applications to Mars's near-surface chemistry.