Operation of the UK Desert Fireball Network

陨石是我们可以利用的最具科学价值的岩石之一，但我们几乎不受它们来自哪里的限制。在没有空间背景的情况下，解释其中包含的早期太阳系过程的记录变得极其困难。人们试图通过获取单个陨石坠落的轨道来提供这一背景(这使我们能够追踪样本到它的起源)。这可以通过有组织的火球天文台网络(旨在拍摄火球、计算轨道、三角测量坠落位置和找回陨石)或通过偶然观察和恢复来实现。但经过几十年的工作，目前只找到了少数几块有轨道的陨石。问题不在于陨石坠落的数量--仅加拿大陨石观测和恢复项目就观察到了50多次陨石坠落事件。问题出在位置上。陨石是一种小的深色岩石，在以前网络所在的植被覆盖的地区很难找到。事实上，在地球表面上，可以进行野外搜索并有现实成功机会的地方相对较少。尽管这是一个重大问题，但它有一个相对简单的解决方案：在一个已知适合回收陨石的地方建立一个网络。到2007年12月，我已经在澳大利亚沙漠完成了一个由四个火球天文台组成的试验网络的建设，以证明这一概念。我们团队的第一次搜索是在2008年10月进行的。在搜索的第一天，我们在距离预计坠落位置不到100米的地方找到了这块陨石。描述这项工作的论文于2009年9月发表在《科学》杂志上，并引起了媒体的极大兴趣，包括在线新闻机构中的70多篇文章。我们的近期目标是寻求资金，使我们能够建立一个由大约16个天文台组成的完整的沙漠火球网络，探测澳大利亚约100万平方公里的火球，并每年观测10-15个瀑布。这是一个与以前的网络数量相似的天文台，也是一个类似的探测区域。这里的不同之处在于，在澳大利亚沙漠建立一个网络将使我的团队能够回收陨石。在这种类型的网络中，我们在一年内发射的带有轨道的陨石将比200年来观测到的陨石还多。在3到4年的时间里，我们将拥有一个统计上很大的陨石轨道数据集--这样的数据集不仅会给这个领域带来革命性的变化，而且会产生远远超出这个领域的影响。课本将被重写。通过轨道和反射光谱的相似性将陨石与特定的近地小行星联系起来，将有效地为我们提供这些天体的样品返回任务，而不需要航天器。此外，我们的计算表明，观测和回收彗星陨石是真正有可能的--从行星科学样本分析的角度来看，这是一个真正的“圣杯”。星尘(2.12亿美元)、深度撞击(3.3亿美元)和罗塞塔(约9.8亿美元)太空任务证明了彗星样本作为太阳系早期过程的见证者的价值。然而，在寻求资金以显著扩大该系统的同时，我们需要保持我们的试验网络的持续运行。这就是这项提议的目的。维持目前的网络运作、开发数字系统和组织实地工作需要一名全职的PDRA。我们目前的模拟系统每年观察到2-3次坠落：我们也在申请实地工作资金来覆盖这些搜索。额外的恢复将支持扩大该系统的理由。

Meteorites are amongst the most scientifically valuable rocks available to us, but we have virtually no constraint on where they come from. With no spatial context, interpreting the record of early Solar System processes that they contain becomes extremely difficult. Attempts have been made to provide that context, by getting orbits for individual meteorite falls (allowing us to track a sample back to its origin). This can be accomplished either by organised networks of fireball observatories (designed to photograph fireballs, calculate orbits, triangulate fall positions, and recover meteorites), or through chance observation and recovery. But after decades of work only a handful of meteorites with orbits have been recovered. The problem was not numbers of meteorite falls - the Canadian Meteorite Observation and Recovery Project alone observed over 50 meteorite-dropping events. The problem was location. Meteorites are small dark rocks, which are difficult to find in the vegetated areas where previous networks were sited. In fact, there are relatively few places on the Earth's surface where field searches can be mounted with a realistic chance of success. Although this is a significant problem, it has a relatively simple solution: construct a network in a place known to be suitable for recovering meteorites. By December 2007 I had completed construction of a trial network of four fireball observatories in the Australian desert to prove the concept. My team's first search was conducted in October 2008. We recovered the meteorite within 100m of the predicted fall position, on the first day of the search. The paper describing this work appeared in Science in September 2009 and generated substantial media interest, including over 70 articles in online news outlets. Our near-term goal is to pursue funding that would allow us to build a full Desert Fireball Network of ~16 observatories, detecting fireballs over ~1 million km2 of Australia and observing 10-15 falls per year. This is a similar number of observatories to previous networks, and a similar detecting area. The difference here is that putting a network in the Australian desert will allow my team to recover the meteorites. In a single year with this type of network we would deliver more meteorites with orbits than have been recovered in 200 years of observations. In a 3-4 year period we would have a statistically large dataset of meteorites with orbits - a dataset like that would not only revolutionise this field, it would have repercussions far beyond it. Textbooks would be re-written. Linking meteorites to specific near-Earth asteroids through similarities in orbits and reflectance spectra would effectively provide us with sample-return missions to those objects, but without the need for spacecraft. In addition, our calculations show that there is the real potential to observe and recover a cometary meteorite - a true 'Holy Grail' in terms of planetary science sample analysis. The Stardust (US$212 million), Deep Impact (US$330 million), and Rosetta (~US$980 million) space missions are testimony to the value placed on cometary samples as witnesses of early Solar System processes. However, while pursuing funding to significantly expand the system we need to maintain the continuous operation of our trial network. That is the purpose of this proposal. Maintaining current network operations, developing a digital system, and organising fieldwork requires a full-time PDRA. Our current analogue system is observing ~2-3 falls per year: we are also requesting fieldwork funding to cover those searches. Additional recoveries will bolster the case for expanding the system.