Discovery, Follow-up, and Calibration of Near-Earth Objects

近地天体的发现、跟踪和校准

• 批准号: 0709500
• 负责人: David Tholen
• 金额: $ 30万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0709500&HistoricalAwards=false
• 关键词: Discovery; Follow; up; Calibration; Near

AST 0709500TholenDr. Tholen will use this award to address three tasks related to near-Earth objects (NEOs). The first task is a continuation of efforts to find new NEOs at solar elongations of less than 90 deg, where objects in certain types of orbits can spend the majority, if not the entirety, of their time. The secondtask is for follow-up astrometry of NEOs, concentrating on objects in the 20 to 24 apparent magnitude range, where little follow-up capability currently exists. The third task involves the acquisition of calibrated photometry of NEOs in the 17 to 19 absolute magnitude range to do abetter job of determining the true number of objects brighter than absolute magnitude 18. The Earth orbits the Sun in a swarm of asteroidal debris ranging in size from roughly 10 km down to tiny dust particles. The size-frequency distribution of this debris is such that only a few objects exist at the large end of the distribution, while billions of dust particles pervade the inner Solar System. The rate of collision between these objects and the Earth is proportional to their number. While collisions with dust particles are essentially continuous, the visible manifestation being known as meteors, collisions with larger objects are correspondingly rarer. A 50 m object hits the Earth every few hundred years, the most recent example being the Tunguska event of 1908. The effects of even larger objects colliding with the Earth are potentially devastating, the demise of the dinosaurs 65 million years ago being attributed to the impact of a 10 km object. To inventory potentially hazardous asteroids, several groups are surveying the Solar System beyond the orbit of the Earth, but little attention has been given to the region of the Solar System interior to the Earth's orbit. Previous survey work at small solar elongations has resulted in perhaps the most significant NEO discovery to date, that of (99942) Apophis, a 300 m object that will pass within 6 Earth radii on 2029 April 13. During a 20-year span centered on the date of discovery, this object spends 95 percent of its time at solar elongations of less than 90 deg. How many other similar objects are there? This program is designed to answer that important question. Astrometric follow-up of the brighter NEOs found by the professional surveys is an activity that involves hundreds of amateur astronomers throughout the world, with no gender, ethnic, or geographic boundaries. This survey will be no different in this regard. The project will directly involve a postdoctoral fellow and/or a graduate student, thus providing both education and training in the subjects of astrometry, photometry, and celestial mechanics. Because of the apparent connection between asteroid impacts and the extinction of the dinosaurs, the subject of near-Earth asteroids has become nearly as popular with younger students as has the subject of dinosaurs. It provides the opportunity to educate the public about the structure of the Solar System beyond the eight major planets traditionally memorized in grade school. And although the probability of finding an object of significant size on a collision course with Earth in the near future is quite small, the broader impact of such a discovery would be enormous, including the topics of disaster preparation, impact prediction, and threat mitigation. So popular has the subject become in recent years that it has spawned two major theatrical motion pictures, a television mini-series, and numerous documentaries.***

AST 0709500THOLENDR。托伦（Tholen）将使用该奖项来解决与近地对象（NEOS）有关的三个任务。第一个任务是继续努力在不到90度的太阳伸长率上找到新的NEO，在某些类型的轨道上的对象可以花费大部分（如果不是整个）的时间。第二任务是用于NEOS的后续星形统计，集中在20至24个明显幅度范围内的物体上，目前几乎没有后续功能。第三个任务涉及在17至19个绝对幅度范围内采集NeoS的校准光度法，以进行缩小的工作，以确定比绝对幅度18的物体的真实数量。地球绕着大小的小行星碎屑绕着太阳绕着太阳，大小范围从大约10 km到微小的粉尘颗粒。这种碎片的尺寸频率分布使得只有少数物体存在于分布的大端，而数十亿个灰尘颗粒遍布内部太阳系。这些物体与地球之间的碰撞速率与它们的数量成正比。尽管与灰尘颗粒的碰撞本质上是连续的，但可见的表现称为流星，但与较大物体的碰撞相应地相应地稀有。一个50 m的物体每几百年击中地球，最新的例子是1908年的通古斯卡事件。甚至更大的物体与地球相撞的影响可能是毁灭性的，6500万年前的恐龙的消亡归因于10 km对象的影响。对于库存潜在的危险小行星，几个群体正在调查地球轨道之外的太阳系，但是对地球轨道内部太阳系区域的关注很少。先前的小太阳伸长的调查工作可能导致了迄今为止最重要的NEO发现，即（99942）Apophis，这是一个300 m的物体，该物体将于4月13日在2029年4月13日的6个地球半径内通过。在发现日期的20年中，该对象的时间为95％的太阳能延长，不到90度。还有几个其他类似的对象？该程序旨在回答这个重要问题。专业调查发现的更明亮的NEO的星体随访是一项活动，涉及全世界数百名业余天文学家，没有性别，种族或地理界限。在这方面，这项调查将没有什么不同。该项目将直接涉及博士后研究员和/或研究生，从而在天体，光度法和天体力学的学科中提供教育和培训。由于小行星的影响与恐龙的灭绝之间存在明显的联系，因此，近地小行星的主题在年轻学生中几乎与恐龙的主题一样流行。它提供了机会，向公众教育太阳系的结构以外的八个主要行星在小学时期都记住了。尽管在不久的将来与地球碰撞过程中发现大小的对象的可能性很小，但这种发现的更广泛影响将是巨大的，包括灾难准备，影响预测和减轻威胁的主题。近年来，这一主题如此受欢迎，以至于它催生了两张主要的戏剧电影，一个电视迷你系列和许多纪录片。***