Observational Study of the Rotation Rates of Very Small Near-Earth Asteroids

非常小的近地小行星自转速率的观测研究

• 批准号: 0908868
• 负责人: Eileen Ryan
• 金额: $ 28.74万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2012-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0908868&HistoricalAwards=false
• 关键词: Observational; Study; Rotation; Rates; Very

AST-0908868Eileen RyanThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This project is motivated by our lack of knowledge of the physical properties of the very smallest Near-Earth Asteroids (NEAs) now being discovered. This is particularly true for rotation periods, which can provide information about an asteroid's internal composition, degree of fracture, and collisional history. Current data suggest that NEAs smaller than 200 meters in diameter rotate faster than 2.2 hours, which is the theoretically derived critical rotation limit for strengthless ellipsoids, while larger bodies rotate more slowly. This suggests that the small fast rotating objects are solid and so are likely to be individual fragments that once made up a rubble pile parent body that was disrupted by a catastrophic impact. However, the sample size of small asteroids with known rotation periods is small and a more robust statistical sample is needed. The state-of-the-art 2.4-meter telescope at the Magdalena Ridge Observatory will be used to determine rotation periods (through light curves) and material classifications (through spectrophotometry) for 15-20 small NEAs per year. By the end of the three year project, the number of characterized small NEAs is expected to have more than doubled.If, as suggested by preliminary observations by the PIs, a large percentage of slowly rotating small bodies exists, it may well be the case that "rubble piles" (versus monolithic or coherent bodies) are common at the low-mass end. Such a result is important in assessing and planning for the threat posed by these objects. The project will be carried out at a minority serving institution and provide research and training experiences for these students (though no direct support is included here). The researchers will include Near-Earth Asteroid observations and the concepts involved in this research as part of a Masters of Science Teaching program for K-12 educators, and they routinely give public talks on these topics.

AST-0908868Eileen Ryanthis奖是根据2009年的《美国复苏和再投资法》（公法111-5）资助的。该项目是由于我们对现在发现了最小的近地小行星（NEAS）的物理特性的知识缺乏了解。 对于旋转期尤其如此，可以提供有关小行星内部组成，断裂程度和碰撞病史的信息。 当前数据表明，直径小于200米的NEAS旋转的速度快于2.2小时，这是无效椭圆形的理论得出的临界旋转极限，而较大的身体旋转速度较慢。 这表明，小的快速旋转物体是固体的，因此很可能是单个碎片，曾经构成碎石堆的母体，受到灾难性冲击的破坏。 但是，具有已知旋转周期的小行星的样本量很小，需要更健壮的统计样本。 Magdalena Ridge天文台的最先进的2.4米望远镜将用于确定每年15-20个小NEAS的旋转周期（通过光曲线）和材料分类（通过分光光度法）。 到三年项目结束时，特征性的小脂肪的数量预计将增加一倍以上。如果通过PIS的初步观察表明，很大一部分缓慢旋转的小体可以存在，很可能是“瓦砾桩”（相反的单层或均匀的身体）在低水平的最终地区是常见的。 这样的结果对于评估和计划这些物体构成的威胁很重要。 该项目将在少数派服务机构进行，并为这些学生提供研究和培训经验（尽管此处不包括直接支持）。 研究人员将包括接近地球的小行星观察和本研究中涉及的概念，这是针对K-12教育者的科学教学硕士课程的一部分，他们通常会就这些主题进行公开谈判。