Water ice cliffs on Mars Some locations on Mars are known to have water ice just below the surface, but how much has remained unclear. Dundas et al. used data from two orbiting spacecraft to examine eight locations where erosion has occurred. This revealed cliffs composed mostly of water ice, which is slowly sublimating as it is exposed to the atmosphere. The ice sheets extend from just below the surface to a depth of 100 meters or more and appear to contain distinct layers, which could preserve a record of Mars' past climate. They might even be a useful source of water for future human exploration of the red planet. Science, this issue p. 199 Cliffs on Mars expose water ice sheets present just below the surface in many locations. Thick deposits cover broad regions of the Martian mid-latitudes with a smooth mantle; erosion in these regions creates scarps that expose the internal structure of the mantle. We investigated eight of these locations and found that they expose deposits of water ice that can be >100 meters thick, extending downward from depths as shallow as 1 to 2 meters below the surface. The scarps are actively retreating because of sublimation of the exposed water ice. The ice deposits likely originated as snowfall during Mars’ high-obliquity periods and have now compacted into massive, fractured, and layered ice. We expect the vertical structure of Martian ice-rich deposits to preserve a record of ice deposition and past climate.

中文翻译：

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火星中纬度暴露的地下冰盖

火星上的水冰悬崖 已知火星上的一些地方在地表以下有水冰，但具体有多少尚不清楚。邓达斯等人。使用来自两个轨道航天器的数据来检查发生侵蚀的八个位置。这揭示了主要由水冰组成的悬崖，当它暴露在大气中时，它正在慢慢升华。冰盖从地表下方延伸到 100 米或更深，似乎包含不同的层，这可以保存火星过去气候的记录。它们甚至可能成为未来人类探索这颗红色星球的有用水源。科学，这个问题 p。199 火星上的悬崖在许多地方暴露了存在于地表以下的水冰盖。厚厚的沉积物覆盖了火星中纬度的广阔区域，具有光滑的地幔；这些地区的侵蚀形成了暴露地幔内部结构的悬崖。我们调查了其中的 8 个地点，发现它们暴露出厚度超过 100 米的水冰沉积物，从地表以下 1 到 2 米的深处向下延伸。由于暴露的水冰升华，悬崖正在积极撤退。冰沉积很可能起源于火星高倾角时期的降雪，现在已经压实成块状、破碎和分层的冰。我们期望火星富含冰的沉积物的垂直结构能够保存冰沉积和过去气候的记录。从浅至地表以下 1 至 2 米的深处向下延伸。由于暴露的水冰升华，悬崖正在积极后退。冰沉积很可能起源于火星高倾角时期的降雪，现在已经压实成块状、破碎和分层的冰。我们期望火星富含冰的沉积物的垂直结构能够保存冰沉积和过去气候的记录。从浅至地表以下 1 至 2 米的深处向下延伸。由于暴露的水冰升华，悬崖正在积极后退。冰沉积很可能起源于火星高倾角时期的降雪，现在已经压实成块状、破碎和分层的冰。我们期望火星富含冰的沉积物的垂直结构能够保存冰沉积和过去气候的记录。