Science. 1992 Aug 7;257(5071):779-82. doi: 10.1126/science.257.5071.779.
Because of their short dynamical lifetimes, the population of near-Earth asteroids (NEAs) must be resupplied. Two sources have been hypothesized: main-belt asteroids and extinct comet nuclei. The difficulty of making physical measurements for similar sized (diameter D less than 5 kilometers) main-belt asteroids and comet nuclei has limited comparative tests for distinguishing between these alternatives. A new survey of physical properties for D < 5 kilometers main-belt asteroids reveals that their spin rate and shape distributions are similar to those of NEAs, as is fully consistent with a main-belt origin for most NEAs. Physical data on comet nuclei are limited. If the existing sample is representative of the comet population, analysis of the asteroid and comet samples constrains the fraction of comet nuclei to between 0 and 40 percent of the total NEA population.
由于近地小行星 (NEA) 的动态寿命较短，因此必须对其进行补充。有两个来源被假设：主带小行星和灭绝的彗星核。由于对类似大小（直径 D 小于 5 公里）的主带小行星和彗星核进行物理测量的难度有限，因此限制了对这些替代方案进行区分的比较测试。对 D < 5 公里主带小行星的物理性质的新调查表明，它们的自转速率和形状分布与 NEA 相似，这完全符合大多数 NEA 的主带起源。彗星核的物理数据有限。如果现有样本能代表彗星种群，那么对小行星和彗星样本的分析就可以限制彗星核在 NEA 总种群中的比例在 0 到 40%之间。
