Measurements from the InSight lander radiometer acquired after landing are used to characterize the thermophysical properties of the Martian soil in Homestead hollow. This data set is unique as it stems from a high measurement cadence fixed platform studying a simple well-characterized surface, and it benefits from the environmental characterization provided by other instruments. We focus on observations acquired before the arrival of a regional dust storm (near Sol 50), on the furthest observed patch of soil (i.e., ∼3.5 m away from the edge of the lander deck) where temperatures are least impacted by the presence of the lander and where the soil has been least disrupted during landing. Diurnal temperature cycles are fit using a homogenous soil configuration with a thermal inertia of 183 ± 25 J m⁻² K⁻¹ s^−1/2 and an albedo of 0.16, corresponding to very fine to fine sand with the vast majority of particles smaller than 140 μm. A pre-landing assessment leveraging orbital thermal infrared data is consistent with these results, but our analysis of the full diurnal temperature cycle acquired from the ground further indicates that near surface layers with different thermophysical properties must be thin (i.e., typically within the top few mm) and deep layering with different thermophysical properties must be at least below ∼4 cm. The low thermal inertia value indicates limited soil cementation within the upper one or two skin depths (i.e., ∼4–8 cm and more), with cement volumes <<1%, which is challenging to reconcile with visible images of overhangs in pits.

中文翻译：

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InSight Lander 附近的土壤热物理性质源自 50 个辐射计测量值

着陆后获得的 InSight 着陆器辐射计测量结果用于表征 Homestead 空心中火星土壤的热物理特性。该数据集是独一无二的，因为它源于一个高测量节奏的固定平台，研究一个简单的良好表征的表面，并且受益于其他仪器提供的环境表征。我们专注于在区域沙尘暴（Sol 50 附近）到来之前获得的观测结果，即观测到的最远的土壤斑块（即距离着陆器甲板边缘约 3.5 m），那里的温度受到的影响最小。着陆器和着陆过程中土壤破坏最少的地方。^{使用热惯性为 183 ± 25 J m -2}  K的均质土壤配置拟合昼夜温度循环^-1  s ^-1/2和 0.16 的反照率，对应于绝大多数颗粒小于 140 μm 的极细至细砂。利用轨道热红外数据进行的着陆前评估与这些结果一致，但我们对从地面获取的全昼夜温度循环的分析进一步表明，具有不同热物理特性的近地表层必须很薄（即，通常在前几个mm）和具有不同热物理性质的深层必须至少低于∼4 cm。低热惯性值表明在上部一到两个表皮深度（即~4-8 cm 及以上）内土壤胶结有限，水泥体积<<1%，这很难与坑中突出物的可见图像相协调。