How Many Hydrated NEOs Are There?
How Many Hydrated NEOs Are There?
复制标题
有多少水合近地天体？
DOI：
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
F. DeMeo
中科院分区：
文献类型：
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作者：
A. Rivkin;F. DeMeo
水合矿物是早期太阳系历史的踪迹，已被提议作为太空经济活动的可能焦点。近地天体(NEO)对这两者都很重要，特别是对该社区中最容易接近的成员。由于确定的水合近地天体很少，我们使用CH光谱类小行星作为水合小行星的替代，并利用已发表的关于近地天体输送、主带分类分布、近地天体分类分布和观测轨道分布的工作来估计具有不同阈值大小和不同可及程度的水合小行星的数量。我们预计在直径1公里的已知近地天体群体中将存在53±27颗CH小行星，并使用两种不同的方法来估计其中17±9颗小行星的往返行程比月球表面更容易到达。如果不需要定义最小大小，我们预计会有700±350个满足可访问性标准的水合对象。虽然很少有大于1公里的未知近地天体，但预计尚未发现的较小的近地天体中也会有相当多的水合天体。最后，我们估计，水合的近地天体不太可能带来足够的水来解释在月球两极发现的冰，尽管在月球表面的撞击地点附近，可能会发现小行星运送的水合矿物。
Hydrated minerals are tracers of early solar system history and have been proposed as a possible focus for economic activity in space. Near‐Earth objects (NEOs) are important to both of these, especially the most accessible members of that community. Because there are very few identified hydrated NEOs, we use the Ch spectral class of asteroids as a proxy for hydrated asteroids and use published work about NEO delivery, main‐belt taxonomic distributions, NEO taxonomic distributions, and observed orbital distributions to estimate the number of hydrated asteroids with different threshold sizes and at different levels of accessibility. We expect 53 ± 27 Ch asteroids to be present in the known population of NEOs >1‐km diameter, and using two different approaches to estimate accessibility we expect 17 ± 9 of them to be more accessible on a round trip than the surface of the Moon. If there is no need to define a minimum size, we expect 700 ± 350 hydrated objects that meet that accessibility criterion. While there are few unknown NEOs larger than 1 km, the population of smaller NEOs yet to be discovered could also be expected to contain proportionally many hydrated objects. Finally, we estimate that hydrated NEOs are unlikely to bring enough water to account for the ice found at the lunar poles, though it is possible that asteroid‐delivered hydrated minerals could be found near their impact sites across the lunar surface.