Deposition of CO2 ice under Martin polar conditions: Textures, NIR reflectance and response to thermal stresses

Abstract

We created an experimental setup to simulate polar martian conditions and study the behavior of CO₂ ice. This paper summarizes the observations from the first year of operation of the MARs Volatile and Ice evolutioN Chamber (MARVIN) at York University (2020−2021). We observed three different textures of CO₂ ice deposited on the cold plate and recorded the reflectance of the ice in the near-infrared range of 1–2.5 μm throughout its deposition. Polycrystalline translucent slab ice formed in all experiments when the environmental conditions were similar to those on Martian poles, as reported by other authors (Portyankina et al., 2019; Schmitt et al., 2020). Fine-grained CO₂ ice formed at temperatures under 140 K. Additionally, we observed the fine-grained CO₂ ice sintering and integrating into an existing translucent slab ice. We further discuss the challenges of measuring the reflectance of the translucent CO₂ ice due to the high specular reflectance of metal substrates. We measured an increase in reflectance by about 40% due to the thermal cracking of a CO₂ slab. Finally, we recorded the fracturing of a CO₂ ice slab by a gas pocket formed under the ice in an experimental run that simulated basal sublimation induced jet-like gas eruptions.