Planetary Origins and Development (OxPOD)

根据对陨石中最古老粒子的放射性测年，太阳系大约在45.7亿年前由一个扁平的气体和尘埃盘形成。随着太阳在中心经历其最早的，激烈的发展阶段，氢，氦，水氨和甲烷等气体被吹到最外面的部分，超出小行星带，在那里它们被浓缩成巨大的行星木星，土星，天王星和海王星。内太阳系主要由尘埃组成，这些尘埃在数千年的时间里逐渐聚集在一起，并成长为大量10-100公里大小的天体。在300万到3000万年的时间里，这些小天体碰撞并成长为内行星，水星，金星，地球和火星，留下小行星带中较小的小行星作为行星生长之前时期的残留物。该项目旨在通过结合陨石研究，了解小行星上和行星生长期间发生的一些最重要的过程。以及旨在模拟太阳系最早期行星生长条件的实验。我们特别感兴趣的是，内行星如何获得所谓的“中等挥发性元素”，如硫、氯、锌和铅，以及这些和其他挥发性元素，特别是惰性气体氦、氖、氩、氪和氙，如何被脱气到大气中并再循环到行星内部。我们还在建立能力，以实验方式模拟外太阳系行星天王星和海王星深处的条件，据信这两颗行星含有大量甲烷。我们的5个相互关联的项目可以单独总结如下：A。讨论了太阳系内行星如何获得硫和氯等中等挥发性非金属目前浓度的问题，并询问获取机制是否与获取锌、铅、锑和铜等挥发性金属的机制不同。这涉及到在1300摄氏度左右的温度下熔化含有这些元素的岩石，并确定不同元素在大气中损失的速度。硫在木卫一内部循环的物理和化学途径是什么？木卫一是木星的卫星，是太阳系中火山活动最活跃的天体，其大气层不断被火山喷发出的富含硫的气体所补充。该项目使用计算机模拟来解决硫排放到大气中，在表面冷凝，然后再循环到走廊的方式。火星表面的水合作用是如何导致包括水、惰性气体、氯、溴和碘在内的挥发物循环的？这些气体通过被锁定在一种常见的矿物--闪石中而固定在火星表面。该项目的目的是通过高压实验确定这些元素在多大程度上可以被捕获在角闪石中并再循环到火星通道。水是如何加入到富含碳的小行星中导致磁铁矿的生长的？大部分碳质陨石在其母体上经历了水蚀变，磁铁矿是所涉及过程的重要线索。本项目旨在实验室模拟导致上述类型磁铁矿的转化过程。在天王星和海王星内部的极端压力和温度条件下，甲烷和水的性质是什么？该项目旨在确定甲烷和水的哪些化合物在这些巨行星的内部是稳定的，并提供数据，以便能够对行星特性进行建模。

Based on radioactive dating of the oldest particles in meteorites, the solar system formed from a flattened disk of gas and dust about 4.57 billion years ago. With the sun at the centre going through its earliest, violent stages of development, gases such as hydrogen, helium, water ammonia and methane were swept to the outermost parts, beyond the asteroid belt, where they were condensed into the giant planets Jupiter, Saturn, Uranus and Neptune. The inner solar system consisted predominantly of dust and this dust gradually clumped together over 10's of thousands of years and grew into a large number of bodies of 10-100 km in size. Over periods of 3 to 30 million years these small bodies collided and grew into the inner planets, Mercury, Venus, Earth and Mars, leaving the smaller asteroids of the asteroid belt as remnants of the period before the planets grew.This project is aimed at the understanding of some of the most important processes which took place on small asteroids and during growth of the planets using a combination of studies of meteorites and experiments aimed at simulating conditions on growing planets during the earliest history of the solar system. We are particularly interested in how the inner planets acquired their inventories of the so-called "moderately volatile elements" such as sulphur, chlorine, zinc and lead, and how these and other volatile elements, notably the noble gases Helium, Neon, Argon, Krypton and Xenon, are degassed to the atmosphere and recycled to the planet's interior. We are also building the capacity to simulate experimentally the conditions deep within the outer solar system planets Uranus and Neptune, which are believed to contain significant amount of methane. Individually our 5 inter-related projects may be summarised as follows:A. Addresses the question of how the planets of the inner solar system obtained their current concentrations of moderately volatile non-metals such as sulphur and chlorine and asks if the mechanisms of acquisition are different from those in which the volatile metals such as zinc, lead antimony and copper were acquired. This involves melting rocks containing these elements at temperatures of about 1300oC and determining the rates at which the different elements are lost to the atmosphere.B. What are the physical and chemical pathways by which sulphur is cycled through Io's interior? Io, a moon of Jupiter, is the most volcanically active body in the solar system and its atmosphere is being continually replenished by sulphur-rich gases emitted by volcanoes. This project uses computer modelling to address the ways in which sulphur is emitted to the atmosphere, condensed on the surface and then recycled to the interior.C. How has hydration of the martian surface led to recycling of volatiles including water, the noble gases, chlorine, bromine and iodine? These gases become fixed on Mars' surface by being locked into a common mineral, amphibole. The aim of this project is to determine, by high pressure experiment, the extents to which these elements can be trapped in amphibole and recycled to the martian interior.D. How did addition of water to carbon-rich asteroids lead to the growth of magnetite? A large proportion of carbonaceous meteorites have undergone aqueous alteration on their parent bodies and magnetite is an important clue to the processes involved. This project is aimed at experimentally simulating in the laboratory the transformation processes which lead to magnetite of the types observed.E. What are the properties of methane and water under the extreme pressure and temperature conditions in the interiors of Uranus and Neptune? This project is aimed at determining which compounds of methane and water are stable in the interiors of these giant planets and providing data to enable modelling of the planetary properties.