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Thermophysical Properties and Surface Heterogeneity of Landing Sites on Mars From Overlapping Thermal Emission Imaging System (THEMIS) Observations
Journal of Geophysical Research: Planets ( IF 3.9 ) Pub Date : 2021-05-20 , DOI: 10.1029/2020je006713
Alexandra A. Ahern 1 , A. Deanne Rogers 1 , Christopher S. Edwards 2 , Sylvain Piqueux 3
Affiliation  

Orbitally derived thermal inertia (TI) values of surfaces allow for remote interpretation of rock and sediment physical characteristics. The evolving local times of the Mars Odyssey Thermal Emission Imaging System (THEMIS) mission have enabled surface temperature data collection over multiple seasons and local times over ∼9 Mars years (MY). We utilize this higher temporal resolution data set to separate TI values of individual materials within THEMIS pixels (100 m sampling). In this study, we focus on geologic units within Gusev, Gale, and Jezero crater landing sites to determine their respective TI and ground-truth our methods. We use the KRC model to predict temperatures for a range of homogeneous and two-component thermophysical mixing scenarios (laterally and vertically heterogeneous), and compare those to THEMIS brightness temperatures. The Gusev and Gale crater results are consistent with rover-based evaluations, indurated or clast-covered sands. The best-fit scenarios along the Jezero crater volcanic floor unit show low to moderate TI values representative of coarse sediment, volcaniclastic, or pyroclastic rocks. The light toned unit and western fan deposits both indicate sands and a moderate TI component; we interpret this as heavy fracturing within the rock. Difficulties in modeling some THEMIS temperatures are attributed to daily weather effects, local atmospheric dust variability, and real surface changes over time (e.g., dust deposition and removal); we also observe that some temperature observations lead to non-unique modeled physical solutions. Nevertheless, these methods can still rule out a significant range of material properties and provide meaningful geologic information about Mars’ surface.

中文翻译:

来自重叠热发射成像系统 (THEMIS) 观测的火星着陆点的热物理特性和表面异质性

轨道导出的表面热惯性 (TI) 值允许远程解释岩石和沉积物的物理特性。火星奥德赛热发射成像系统 (THEMIS) 任务不断演变的当地时间使得在大约 9 个火星年 (MY) 的多个季节和当地时间收集表面温度数据成为可能。我们利用这个更高的时间分辨率数据集来分离 THEMIS 像素内单个材料的 TI 值(100 m 采样)。在这项研究中,我们专注于 Gusev、Gale 和 Jezero 陨石坑着陆点内的地质单元,以确定它们各自的 TI 和我们的方法的地面实况。我们使用 KRC 模型来预测一系列同质和双组分热物理混合场景(横向和垂直异质)的温度,并将这些与 THEMIS 亮度温度进行比较。Gusev 和 Gale 陨石坑的结果与基于漫游车的评估、硬化或碎屑覆盖的砂岩一致。沿 Jezero 火山口火山底板单元的最适合场景显示出代表粗沉积物、火山碎屑或火山碎屑岩的低至中等 TI 值。浅色调单元和西部扇形沉积物均表明有沙子和中等 TI 成分;我们将其解释为岩石内的严重破裂。对某些 THEMIS 温度进行建模的困难归因于日常天气影响、当地大气灰尘变化和真实地表随时间的变化(例如,灰尘沉积和清除);我们还观察到一些温度观测会导致非唯一的建模物理解。尽管如此,
更新日期:2021-06-08
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