Accretion rate of cosmic spherules measured at the South Pole
Accretion rate of cosmic spherules measured at the South Pole
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DOI：
10.1038/31894
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发表时间：
1998-04
期刊：
影响因子：
64.8
通讯作者：
S. Taylor;J. Lever;R. Harvey
中科院分区：
文献类型：
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作者：
S. Taylor;J. Lever;R. Harvey
微陨石是在陆地上收集的、小于1毫米左右的外星颗粒，占地球吸积质量的大部分。与陨石相比，微陨石更完整地代表了穿越地球的流星体复合体，应该包括小行星、彗星、火星和月球的碎片，以及太阳前和星际颗粒。由于风化对微粒的破坏、磁性收集或分离技术效率低下、微粒计数低、年龄限制差、或浓缩过程变化很大，以前对存留到地球表面的微流星体通量的测量存在很大的不确定性。在这里，我们描述了一种尝试，以规避这些问题，通过收集数以千计的保存完好，并从南极水井，供应饮用水的斯科特-阿蒙森站的底部的微陨石。利用这些数据，我们已经确定了50-700微米宇宙球粒（熔化的微陨石）的通量和质量分布的精确估计。考虑到样品中未熔化的微陨石的预期丰度，我们的研究结果表明，大约90%的亚毫米粒子进入大气层时蒸发。我们的数据表明，深海沉积物中富含玻璃和小石质球粒的损失，它们为描述微流星体生存概率的模型提供了限制。
Micrometeorites are terrestrially collected, extraterrestrial particles smaller than about 1 mm, which account for most of the mass being accreted to the Earth,. Compared with meteorites, micrometeorites more completely represent the Earth-crossing meteoroid complex, and should include fragments of asteroids, comets, Mars and our Moon, as well as pre-solar and interstellar grains,. Previous measurements of the flux of micrometeoroids that survive to the Earth's surface have large uncertainties owing to the destruction of particles by weathering,,, inefficiencies in magnetic collection or separation techniques,,, low particle counts,, poor age constraint,,,, or highly variable concentrating processes,. Here we describe an attempt to circumvent these problems through the collection of thousands of well preserved and dated micrometeorites from the bottom of the South Pole water well, which supplies drinking water for the Scott–Amundsen station. Using this collection, we have determined precise estimates of the flux and mass distribution for 50–700-µm cosmic spherules (melted micrometeorites). Allowing for the expected abundance of unmelted micrometeorites in the samples, our results indicate that about 90% of the incoming mass of submillimetre particles evaporates during atmospheric entry. Our data indicate the loss of glass-rich and small stony spherules from deep-sea deposits,, and they provide constraints for models describing the survival probability of micrometeoroids,.