Meteorites as free sample-returns: Operation of the UK Desert Fireball Network

陨石作为免费样品返回：英国沙漠火球网络的运营

• 批准号: ST/F003072/1
• 负责人: Philip Bland
• 金额: $ 38.3万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FF003072%2F1
• 关键词: Meteorites; free; sample; returns; Operation

A spatial context to aid interpretation is fundamental to all sample analysis: whether those samples are rocks, medical tests, or police evidence, we need to know where they came from to interpret the results. Meteorites are our only samples of a protoplanetary disk; the only surviving physical record of the formation of our own Solar System (including the variety of local stellar sources that contributed to our disk, and the chemical processes that occurred within it); the only record of how differentiation and core formation occurs in planetesimals. And yet we have virtually no constraint on where they come from. Until we get sample-return missions to numbers of asteroids, what we need are orbits for specific meteorites. Unfortunately, out of tens of thousands of meteorites, we have good orbits for only four, and reasonable orbits for a couple more. The aim of this project is to determine orbits for numbers of meteorites. The results potentially have implications for every area of meteorite study, just as a knowledge of spatial context of any other sample has implications for all subsequent analyses of it. Meteoroids produce a bright fireball as they transit our atmosphere. By photographing the fireball from different angles, the atmospheric track of the object can be determined with great accuracy. If material survives to the surface as a meteorite, this allows us to work out what its orbit was before it entered the atmosphere, and also where it landed on the Earth's surface. This technique has been employed a number of times over the last 50 years, all in temperate regions of the northern hemisphere, but although hundreds meteorite falls have been observed, only four were recovered. The poor success rate is down to the difficulty in recovering a small rock in an area of several square kilometres when there is significant undergrowth. Our solution was rather simple. Over the last few decades, tens of thousands of meteorites have been found in the world's deserts. Put a fireball network in a desert and it should be much easier samples. We have designed a fireball observatory that can operate automatically in the harsh environment of the Australian desert. Based on previous fieldwork in this area, looking for old weathered meteorites, we should have about a 70% chance of finding meteorites that we see land. Our first grant, to put a small network of 3 observatories out in the desert, and test both the technology and concept, began June 2005. Two years on, fireball observatories have been built, deployed in the Australian desert, and successfully integrated with satellite internet and solar power. In addition to fully-functioning autonomous observatories, logistics to maintain them in operation, and support regular fieldwork, are in place. The UK now has a fireball camera network operating in the Australian desert. Orbits have been calculated from 22 fireballs - the first orbits to be determined from southern hemisphere fireballs. And most important: at least one of these fireballs has produced a meteorite on the ground. An expedition to recover this sample - and any others that fall in the meantime - will be mounted in the next field season. Our initial trial network has proven a success. We now need the support that will let us translate this success into a growing collection of meteorites with orbits, finally providing meteorite scientists with that most basic information: a knowledge of where their samples come from.

帮助解释的空间背景是所有样本分析的基础：无论这些样本是岩石、医学测试还是警方证据，我们都需要知道它们来自哪里才能解释结果。陨石是我们唯一的原行星盘样本;我们自己的太阳系形成的唯一幸存的物理记录（包括各种各样的本地恒星来源，有助于我们的磁盘，以及其中发生的化学过程）;唯一的记录是如何分化和核心形成在星子中发生。然而，我们实际上对它们来自哪里没有任何限制。在我们完成对大量小行星的采样返回任务之前，我们需要的是特定陨石的轨道。不幸的是，在数以万计的陨石中，我们只有四颗有良好的轨道，还有几颗有合理的轨道。该项目的目的是确定陨石数量的轨道。这些结果可能对陨石研究的每个领域都有影响，就像任何其他样本的空间背景知识对所有后续分析都有影响一样。流星体在穿过我们的大气层时会产生明亮的火球。通过从不同角度拍摄火球，可以非常准确地确定物体的大气轨迹。如果物质以陨石的形式存活到地表，这使我们能够计算出它进入大气层之前的轨道，以及它在地球表面的着陆点。在过去的50年里，这项技术已经被应用了很多次，都是在北方的温带地区，但是尽管已经观察到了数百颗陨石福尔斯，只有四颗被回收。成功率低的原因是，在几平方公里的地区，当有大量的灌木丛时，很难回收一块小石头。我们的解决方案相当简单。在过去的几十年里，在世界的沙漠中发现了成千上万的陨石。把一个火球网络放在沙漠里，它应该更容易样本。我们设计了一个火球观测站，可以在澳大利亚沙漠的恶劣环境中自动运行。根据以前在这一地区的实地考察，寻找古老的风化陨石，我们应该有大约70%的机会找到陨石，我们看到的土地。我们的第一笔赠款是在沙漠中建立一个由3个观测站组成的小型网络，并测试技术和概念，始于2005年6月。两年后，火球观测站已经建成，部署在澳大利亚沙漠中，并成功地与卫星互联网和太阳能相结合。除了全面运作的自治观测站外，还提供了维持观测站运作和支持定期实地工作的后勤保障。英国现在有一个火球摄像机网络在澳大利亚沙漠中运行。从22个火球中计算出了轨道-这是第一个从南半球火球中确定的轨道。最重要的是：这些火球中至少有一个在地面上产生了陨石。在下一个野外季节，将进行一次探险，以恢复这一样本--以及在此期间掉落的任何其他样本。我们最初的试验网络已经证明是成功的。我们现在需要支持，让我们将这一成功转化为越来越多的陨石轨道，最终为陨石科学家提供最基本的信息：他们的样本来自哪里的知识。