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 0709500 TholenDr.索伦将利用这一奖项来解决与近地天体(NEO)有关的三项任务。第一项任务是继续努力寻找太阳伸长小于90度的新近地天体，在这种情况下，某些类型轨道上的天体可以花费大部分时间，如果不是全部时间的话。第二项任务是对近地天体进行后续天体测量，重点关注视星等在20至24等范围内的天体，这些天体目前几乎没有后续能力。第三项任务涉及获取17到19个绝对星等范围内的近地天体的校准光度测量，以便更好地确定比绝对星等18更亮的天体的真实数量。地球围绕太阳运行的是一群小行星碎片，大小从大约10公里到微小的尘埃颗粒不等。这种碎片的大小-频率分布是这样的：只有几个物体存在于分布的最大端，而内太阳系则弥漫着数十亿个尘埃粒子。这些天体与地球之间的碰撞速度与它们的数量成正比。虽然与尘埃粒子的碰撞基本上是连续的，可见的表现形式被称为流星，但与较大物体的碰撞相对较少。每几百年就有一个50米的物体撞击地球，最近的例子是1908年的通古斯卡事件。更大的物体与地球相撞的影响可能是毁灭性的，6500万年前恐龙的灭绝被归因于一个10公里物体的撞击。为了清查潜在危险的小行星，几个小组正在勘测地球轨道以外的太阳系，但很少有人关注地球轨道内部的太阳系区域。之前的小太阳伸展调查工作可能是迄今为止最重大的近地天体发现，(99942)阿波菲斯，一个300m的天体，将于2029年4月13日通过地球半径6个半径。在以发现日期为中心的20年时间里，该天体95%的时间是在太阳伸长小于90度的情况下度过的。还有多少其他类似的物体？这个项目就是为了回答这个重要的问题。专业调查发现的较亮近地天体的天体测量跟踪是一项涉及世界各地数百名业余天文学家的活动，没有性别、种族或地理界限。这项调查在这方面也不会有什么不同。该项目将直接涉及一名博士后研究员和/或一名研究生，从而提供天体测量学、光度学和天体力学学科的教育和培训。由于小行星撞击和恐龙灭绝之间的明显联系，近地小行星学科几乎和恐龙学科一样受到年轻学生的欢迎。它提供了一个机会，让公众了解太阳系的结构，而不是传统上在小学里记忆的八大行星。尽管在不久的将来发现与地球相撞的重大物体的可能性很小，但这种发现的更广泛影响将是巨大的，包括灾害准备、影响预测和威胁缓解等主题。近年来，这个主题变得如此受欢迎，以至于它催生了两部主要的戏剧电影，一部电视迷你剧，以及许多纪录片。