Department of Geography and Earth Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, USA.
Department of Electrical and Computing Engineering, University of North Carolina at Charlotte, Charlotte North Carolina 28223, USA.
Nat Commun. 2015 Mar 27;6:6712. doi: 10.1038/ncomms7712.
The origins of fractures in Martian boulders are unknown. Here, using Mars Exploration Rover 3D data products, we obtain orientation measurements for 1,857 cracks visible in 1,573 rocks along the Spirit traverse and find that Mars rock cracks are oriented in statistically preferred directions similar to those compiled herein for Earth rock cracks found in mid-latitude deserts. We suggest that Martian directional cracking occurs due to the preferential propagation of microfractures favourably oriented with respect to repeating geometries of diurnal peaks in sun-induced thermal stresses. A numerical model modified here with Mars parameters supports this hypothesis both with respect to the overall magnitude of stresses as well as to the times of day at which the stresses peak. These data provide the first direct field and numerical evidence that insolation-related thermal stress potentially plays a principle role in cracking rocks on portions of the Martian surface.
火星巨石中裂缝的起源尚不清楚。在这里，我们使用火星探测漫游者 3D 数据产品，获得了沿“精神号”巡视路径上 1573 块岩石中 1857 条可见裂缝的方向测量值，并发现火星岩石裂缝的方向与这里为地球中纬度沙漠中发现的岩石裂缝所汇编的方向相似，呈统计上优选的方向。我们认为，火星定向开裂是由于微裂缝优先扩展，这些微裂缝相对于太阳诱发热应力的昼夜峰重复几何形状有利。在此，我们用火星参数对一个经过修正的数值模型进行了研究，该模型不仅支持了整体应力大小的假设，还支持了每天达到峰值的时间。这些数据提供了首个直接的实地和数值证据，表明与太阳辐射有关的热应力可能在火星表面部分地区岩石开裂中起主要作用。
