Bramble Michael S, Hand Kevin P
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA, 91109, USA.
Sci Rep. 2024 Mar 6;14(1):5503. doi: 10.1038/s41598-024-55979-6.
The proposed chloride salt-bearing deposits on Mars have an enigmatic composition due to the absence of distinct spectral absorptions for the unique mineral at all wavelengths investigated. We report on analyses of remote visible-wavelength spectroscopic observations that exhibit properties indicative of the mineral halite (NaCl) when irradiated. Visible spectra of halite are generally featureless, but when irradiated by high-energy particles they develop readily-identifiable spectral alterations in the form of color centers. Consistent spectral characteristics observed in the reflectance data of the chloride salt-bearing deposits support the presence of radiation-formed color centers of halite on the surface of Mars. We observe a seasonal cycle of color center formation with higher irradiated halite values during winter months, with the colder temperatures interpreted as increasing the formation efficiency and stability. Irradiated halite identified on the surface of Mars suggests that the visible surface is being irradiated to the degree that defects are forming in alkali halide crystal structures.
由于在所有研究波长下均未发现独特矿物的明显光谱吸收，火星上拟议的含氯盐沉积物具有神秘的成分。我们报告了对远程可见波长光谱观测的分析，这些观测显示出在辐照时具有石盐（NaCl）矿物特征的特性。石盐的可见光谱通常没有特征，但当受到高能粒子辐照时，它们会以色心的形式产生易于识别的光谱变化。在含氯盐沉积物的反射率数据中观察到的一致光谱特征支持火星表面存在辐射形成的石盐色心。我们观察到色心形成的季节性周期，冬季月份辐照石盐的值较高，较冷的温度被解释为提高了形成效率和稳定性。在火星表面识别出的辐照石盐表明，可见表面正受到辐照，以至于在碱金属卤化物晶体结构中形成了缺陷。
