Wet Chemistry experiments on the 2007 Phoenix Mars Scout Lander mission: Data analysis and results
Wet Chemistry experiments on the 2007 Phoenix Mars Scout Lander mission: Data analysis and results
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DOI：
10.1029/2009je003424
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发表时间：
2010-01-16
影响因子：
4.8
通讯作者：
Young, S. M. M.
中科院分区：
文献类型：
--
作者：
Kounaves, S. P.;Hecht, M. H.;Young, S. M. M.
使用 2007 年凤凰号火星侦察着陆器上的湿化学实验室对三个火星土壤样本进行了化学分析。一份土壤样本是从顶部约 2 厘米（玫瑰红）处获取的，两份土壤样本是在距冰台界面约 5 厘米深度处获取的（女巫 1 和女巫 2）。当以类似于 1:25 土壤与溶液的比例（按体积）与水混合时，一部分土壤成分会溶解。使用离子选择性电极阵列测量离子浓度，并使用电导池测量溶液电导率。测量的浓度代表土壤中的最小可浸出离子，并且不考虑土壤中剩余的物种。描述了用于确定在土壤/溶液混合物中直接测量的七种离子种类的浓度的数据处理和分析。三个样品之间的浓度、pH 值或电导率没有显着差异。通过实验室实验、表面校准的细化和建模，我们确定了在普遍条件下、碳酸盐缓冲和池顶部空间中的 P-CO2 下土壤溶液的 pH 值为 7.7(+/-0.3)。高氯酸根是溶液中的主要阴离子，玫瑰红的浓度为 2.7(+/-1) mM。平衡模型表明，测量的 [Ca2+] 为 0.56(+/-0.5) mM，[Mg2+] 为 2.9(+/-1.5) mM，与饱和溶液的碳酸盐平衡一致。 [Na+]和[K+]分别为1.4(+/-0.6)和0.36(+/-0.3)mM。结果表明，凤凰城着陆点土壤的淋滤部分呈弱碱性，主要成分是碳酸盐和高氯酸盐。然而，应该注意的是，测量的离子和电导率之间存在 5-15 mM 的差异，并且可能存在其他物质。
Chemical analyses of three Martian soil samples were performed using the Wet Chemistry Laboratories on the 2007 Phoenix Mars Scout Lander. One soil sample was obtained from the top similar to 2 cm (Rosy Red) and two were obtained at similar to 5 cm depth from the ice table interface (Sorceress 1 and Sorceress 2). When mixed with water in a similar to 1:25 soil to solution ratio (by volume), a portion of the soil components solvated. Ion concentrations were measured using an array of ion selective electrodes and solution conductivity using a conductivity cell. The measured concentrations represent the minimum leachable ions in the soil and do not take into account species remaining in the soil. Described is the data processing and analysis for determining concentrations of seven ionic species directly measured in the soil/solution mixture. There were no significant differences in concentrations, pH, or conductivity, between the three samples. Using laboratory experiments, refinement of the surface calibrations, and modeling, we have determined a pH for the soil solution of 7.7(+/-0.3), under prevalent conditions, carbonate buffering, and P-CO2 in the cell headspace. Perchlorate was the dominant anion in solution with a concentration for Rosy Red of 2.7(+/-1) mM. Equilibrium modeling indicates that measured [Ca2+] at 0.56(+/-0.5) mM and [Mg2+] at 2.9(+/-1.5) mM, are consistent with carbonate equilibrium for a saturated solution. The [Na+] and [K+] were 1.4(+/-0.6), and 0.36(+/-0.3) mM, respectively. Results indicate that the leached portion of soils at the Phoenix landing site are slightly alkaline and dominated by carbonate and perchlorate. However, it should be noted that there is a 5-15 mM discrepancy between measured ions and conductivity and another species may be present.