Abstract Prototypes of borehole-wall imager instruments were developed and tested at a desert riverbed in Morocco and at a lake’s salty flat in the Atacama desert, to support the drilling activity of ExoMars rover. The onsite recorded borehole images contain information on the context that are lost during the sample acquisition. Benefits of the borehole-wall imaging is the easier maximal energy estimation of a fluvial flow, the detailed information on sedimentation and layering, especially the former existence of liquid water and its temporal changes, including paleo-flow direction estimation from grain imbrication direction. Benefits of laboratory analysis of the acquired samples are the better identification of mineral types, determination of the level of maturity of granular sediment, and identification of the smallest, wet weathered grains. Based on the lessons learned during the comparison of field and laboratory results, we demonstrate that recording the borehole-wall with optical instrument during/after drilling on Mars supports the paleo-environment reconstruction with such data that would otherwise be lost during the sample acquisition. Because of the lack of plate tectonism and the low geothermal gradient on Mars, even Ga old sediments provide observable features that are especially important for targeting Mars sample return and later crewed Mars missions.

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行星钻孔壁成像仪的表征和初步结果——开发现场勘探的方法

摘要 在摩洛哥的沙漠河床和阿塔卡马沙漠的盐湖滩开发并测试了钻孔壁成像仪仪器的原型，以支持 ExoMars 火星车的钻井活动。现场记录的钻孔图像包含在样本采集过程中丢失的背景信息。井壁成像的好处是更容易估计河流流的最大能量，沉积和分层的详细信息，特别是液态水的前存在及其时间变化，包括从颗粒叠瓦方向估计古流向。对采集的样品进行实验室分析的好处是可以更好地识别矿物类型、确定颗粒沉积物的成熟度以及识别最小的湿风化颗粒。基于在现场和实验室结果比较过程中吸取的经验教训，我们证明在火星钻孔期间/之后用光学仪器记录钻孔壁支持古环境重建，否则这些数据将在样本采集过程中丢失。由于缺乏板块构造作用和火星上的低地温梯度，即使是 Ga 古老的沉积物也提供了可观察的特征，这对于瞄准火星样本返回和后来的载人火星任务尤其重要。