Tiny Main-belt Asteroid Spectral Survey (TMASS)

小行星光谱学中一个长期存在的问题是，这些天体的光谱是否会因暴露于太阳风和/或微陨石撞击而随时间变化，这一过程被称为“太空风化”。最近有证据表明，小行星表面确实会发生空间风化，1-5公里的直径范围是一个临界过渡尺寸。这个由安德鲁·里夫金博士领导的研究项目将利用新收集的天文数据，在一个没有其他研究中存在的许多不确定因素的样本中探索太空风化。小行星空间风化的程度和速率将通过收集大约100颗Koronis动力族小行星的可见光和近红外反射光谱来测量。国家设施（基特峰的4米望远镜和红外望远镜设施（IRTF））以及与研究人员机构相关的设施（里夫金在新墨西哥州的阿帕奇角天文台，宾泽尔在智利的麦哲伦望远镜）将用于观测。目标将是直径在1-5公里范围内的物体，这些物体在主带尚未被系统研究过。这项工作的结果将是更好地了解小行星的表面过程和组成。一项对近地天体（NEO）光谱的研究表明，平均距离为1公里及以下的天体几乎没有空间风化的迹象，而距离为5公里及以上的天体的平均光谱与大型主带天体相似。这与小行星表面随着时间的推移而形成的风化产物相一致。然而，已经完成的研究必须假设近地天体具有相同的成分、风化风格和速率，彼此之间以及与主带小行星相同。通过观察动态家族的小成员，并将它们与同一家族的大成员进行比较，这个问题将被消除。通过建立和测量Koronis家族的空间风化程度（或不存在），将确定光谱因这一过程而变化的数量，以及在进行成分解释时（酌情）对其进行校正的途径。该团队已经获得、还原并发表了大量的可见和红外小行星光谱，完全有资格承担这个项目。建立和表征小行星的空间风化程度直接适用于了解其组成和性质。小行星采矿的应用将对确定其表面的真实成分感兴趣，而不是风化的外观。近地天体缓解问题也是如此；一个富含金属的物体可能会因为空间风化或金属浓度高而出现这种情况。这项研究将有助于揭示这两种可能性，如果这样一个物体必须偏转或摧毁，这两种可能性显然是重要的。收集到的数据将尽可能快地向公众公布。作为美国国家科学基金会资助的mit - irtfuhno调查（http://smass.mit.edu/minus.html）.***)的一部分，研究小组之前已经对其他数据进行了这样的处理

AST 0708101RivkinA long-standing problem in asteroid spectroscopy has been the question of whether the spectra of these bodies change with time via exposure to the solar wind and/or micrometeorite impact, a process dubbed "space weathering". Recent evidence is coalescing around the theory that space weathering does occur on asteroid surfaces, and that the 1-5 km diameter range is a critical transition size. This research program led by Dr. Andrew Rivkin will use newly-collected astronomical data to explore space weathering in a sample free of many uncertainties present in other studies.The extent and rate of space weathering on asteroids will be measured by collecting the visible and near-IR reflectance spectra of roughly 100 asteroids in the Koronis dynamical family. National facilities (the 4-m telescope at Kitt Peak and the Infrared Telescope Facility (IRTF)) as well as facilities associated with the researchers' institutions (Apache Point Observatory in New Mexico for Rivkin, the Magellan telescopes in Chile for Binzel) will be used for observations. The targets willbe objects in the 1-5 km diameter range, which have not been systematically studied in the main belt.The result of this work will be a better understanding of the surface processes on and composition of asteroids. A study of Near-Earth Object (NEO) spectra indicates that objects roughly 1 km and smaller on average show little evidence of space weathering, while those 5 km and larger have average spectra like large main-belt objects. This is consistent with the buildup of weathering products with time on asteroid surfaces. However, studies that have been done must assume the NEOs have the same composition and weathering styles and rates as each other and of main-belt asteroids. By observing small members of a dynamical family and comparing them to larger members of the same family, that issue will be removed. By establishing and measuring the degree (or absence) of space weathering in the Koronis family, the amount that spectra can change due to this process, and the road to correcting for it (as appropriate) in making compositional interpretations will be determined. The team have obtained, reduced, and published a large quantity of visible and infrared asteroid spectra, and are well-qualified to undertake this project.Establishing and characterizing the extent of space weathering on asteroids is directly applicable to understanding their composition and nature. Although not a near-term prospect, asteroid mining applications will be interested in determining the true composition of surfaces, not the weathered appearance. The same is true of NEO mitigation concerns; a metal-rich object could appear so due to space weathering or a high concentration of metal. This study will help unravel those twopossibilities, which are of obvious importance if such an object had to be deflected or destroyed. The data collected will be made publicly available as quickly as is practical. The research team have done this before for other data, as part of the NSF-funded MIT-IRTFUHNEO survey (http://smass.mit.edu/minus.html).***