U.S.-France Cooperative Research: Computing the Real Hazard to the Earth from Comets and Asteroids

0128350波特这项为期三年的奖项支持美国-法国天文学合作威廉F。西南研究所的Bottke和尼斯天文台的Alessandro Morbidelli。 该项目涉及近地物体（即穿越或几乎穿越地球轨道的小行星和彗星群）的起源和演变。目前对近地天体群的轨道和大小分布的了解有限，因为地球已知的近地天体受到复杂的观测选择效应的影响，而且在整个近地天体群中只发现了一小部分。美国和法国的研究人员通过开发近地天体去偏轨道和绝对星等分布的定量模型解决了第一个问题。 这一合作已扩展到新的问题：设计近地天体调查方案，以确定如何以及在何处发现最危险或最难发现的近地天体;计算撞击地球和其他地球天体的频率，作为撞击能量的函数;计算月球和类地行星的相对碰撞率;计算长周期彗星和哈雷型彗星群的上限。 法国调查人员为这一合作带来了小行星和彗星动力学以及碰撞碎裂物理学方面的专门知识。 美国在快速积分代码、轨道演变的大规模数值模拟和统计方面的专门知识对此进行了补充。

0128350BottkeThis three-year award supports U.S.-France collaboration in astronomy between William F. Bottke of the Southwest Research Institute and Alessandro Morbidelli of the Observatory of Nice. The project addresses the origin and evolution of near earth objects or NEOs, a population of asteroids and comets crossing or nearly crossing the Earth's orbit. Present knowledge of orbital and size distributions of the NEO population is limited, because the NEOs known to the Earth are biased by complicated observational selection effects and because only a modest fraction of the entire NEO population has been discovered. US and French researchers addressed the first problem through development of quantitative models of debiased orbital and absolute magnitude distribution of NEOs. This collaboration is extended to new problems: design of NEO surveys to determine how and where to find the most hazardous or hard to find NEOs; computation of frequency of impacts on Earth and other terrestrial bodies as a function of the impact energy; computation of the relative collision rate on the moon and terrestrial planets; and computation of the upper limits on long-period and Halley-type comet population. The French investigators bring to this collaboration expertise in asteroid and cometary dynamics and the physics of collision fragmentation. This is complemented by US expertise in fast integration codes; large scale numerical simulations and statistics on orbital evolution.