火星阿卡迪亚平原上的大量冰
Widespread Excess Ice in Arcadia Planitia, Mars
摘要：
火星地下水冰的分布是过去气候的关键制约因素，而埋藏冰的体积浓度（孔隙填充与过量）提供了有关导致其沉积过程的信息。我们调查阿卡迪亚平原的地下通过测量简单的撞击坑的阶地的深度和绘制一个广泛的地下反射雷达探测数据。假设造成阶地的材料强度对比与引起雷达反射的介电界面相同，我们可以结合这些数据来估计上覆材料的介电常数。我们将这些结果与三组分介电混合模型进行比较，以约束组合物。我们的研究结果表明，存在一个广泛分布的、厚度达10米的、体积约为10^4立方千米的过量水冰层。这些冰的积累和长期保存对目前的火星气候模型来说是一个挑战。
英文摘要：
The distribution of subsurface water ice on Mars is a key constraint on past climate, while the volumetric concentration of buried ice (pore-filling versus excess) provides information about the process that led to its deposition. We investigate the subsurface of Arcadia Planitia by measuring the depth of terraces in simple impact craters and mapping a widespread subsurface reflection in radar sounding data. Assuming that the contrast in material strengths responsible for the terracing is the same dielectric interface that causes the radar reflection, we can combine these data to estimate the dielectric constant of the overlying material. We compare these results to a three-component dielectric mixing model to constrain composition. Our results indicate a widespread, decameters-thick layer that is excess water ice ~10^4 km^3 in volume. The accumulation and long-term preservation of this ice is a challenge for current Martian climate models.
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