Experimental Chondrule Formation I - Lightning Discharge Experiments under Microgravity Conditions at the International Space Station

球粒形成实验I——国际空间站微重力条件下的闪电放电实验

• 批准号: 418578734
• 负责人: Professor Dr. Frank Erich Brenker
• 金额: --
• 依托单位: Fachrichtung Mineralogie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/418578734?language=en
• 关键词: Experimental; Chondrule; Formation; Lightning; Discharge

With this project we intend to study the formation mechanism of chondrules, one of the most important and most frequent solids formed within the first million years of the Solar System. Although known for almost hundred years the formation mechanism is still a matter of intense scientific debate. Just recently the discussion about the formation mechanism of chondrules get several new impulses and re-activated a few of the most favorable formation mechanism like nebular lightning discharges (e.g. Johansen and Okuzumi, 2018), nebular shock waves (e.g. Desch et al., 2012; Fedkin et al., 2012) and asteroidal collision (e.g. Sanders and Scott, 2012). In addition several new aspects of the chondrule formation process itself were published (Palme et al., 2015; Friend, 2017). Taking all this into account the lack of experimental chondrule formation at conditions relevant to the solar nebula, e.g under microgravity, is obvious.The new experimental approach presented here will be performed under microgravity conditions aboard the International Space Station during Alexander Gerst´s current space mission. The sample container will returned to Earth in December 2018 for detailed analytical laboratory studies. The experiment was accepted as one of only three experiments within the framework of the “Ueberflieger”- competition. The proposal presented here will cover the detailed analytical study of the sample material after returned to Earth and the evaluation of the full digital video coverage of the experiment.The main goals of the project are:1) Is lightning are reasonable process to produce chondrule like objects under microgravity conditions?2) Do melting of dust aggregates enhance particle growth?3) What are the structural details of the chondrule like objects formed and can they be related to specific known chondrule types expected to form at high cooling rates, like cryptocrystalline, radial olivine or barred olivine chondrules.4) What are the geochemical consequences on chondrules formed by lightning discharges?5) What is the degree of crystallinity obtained?6) Do we see phase separation and/or the formation of other phases like pyroxene, commonly found in chondrules?

通过这个项目，我们打算研究球粒的形成机制，球粒是太阳系最初一百万年内形成的最重要和最常见的固体之一，尽管已知近百年，但其形成机制仍然是一个激烈的科学争论问题。就在最近，关于球粒形成机制的讨论获得了一些新的推动力，并重新激活了一些最有利的形成机制，如星云闪电放电（例如 Johansen 和 Okuzumi，2018），星云冲击波（例如 Desch 等人，2012 年；Fedkin 等人，2012 年）和小行星碰撞（例如 Sanders 和 Scott，2012 年）此外，还发表了球粒形成过程本身的几个新方面（Palme 等人，2012 年）。 2015；Friend，2017）考虑到在与太阳相关的条件下缺乏球粒形成的实验。星云，例如在微重力下，是显而易见的。这里介绍的新实验方法将在亚历山大·格斯特当前的太空任务期间在国际空间站上的微重力条件下进行。样品容器将于 2018 年 12 月返回地球进行详细的分析实验室研究。该实验被接受为“Ueberflieger”竞赛框架内仅有的三个实验之一。此处提出的提案将涵盖返回地球后对样本材料的详细分析研究以及对完整样本的评估。实验的数字视频报道。该项目的主要目标是：1) 闪电是在微重力条件下产生球粒状物体的合理过程吗？2) 尘埃聚集体的熔化是否会促进颗粒生长？3) 闪电的结构细节是什么？形成的类似球粒的物体，它们是否与预期在高冷却速率下形成的特定已知球粒类型有关，例如隐晶质、放射状橄榄石或棒状橄榄石球粒。4）什么是闪电放电对球粒形成的地球化学影响？5) 获得的结晶度是多少？6) 我们是否看到球粒中常见的相分离和/或辉石等其他相的形成？