Studies on Planetary Formation and Evolution at Bristol

拟议的工作遵循行星体的发展，从其原材料的形成到其大气层的功能。我们的注意力从最早的太阳系开始，当时太阳周围存在唯一的细粒物质。我们都将看到这个星云中一种关键放射性核素的分布，以及行星形成初期气体与固体的分离。这将告诉我们可能形成的行星的成分，以及它们是否会大规模融化。在行星成长的历史中，一个重要的事件是金属下沉到它的中心，形成一个核心。这在地球上是很好理解的，但对于较小的行星体则不然。我们将使用一种新颖的同位素测量最大的小行星之一（灶神星），月球和火星的核心大小。这种新的方法是可能的，因为我们有能力进行精确的同位素测量，并将它们与实验室中的熔化实验相结合。这种方法背后的想法是，我们几乎没有这些行星体的样本，而地球上使用的技术对这些样本不起作用，这些样本在到达表面的途中经历了未知的扰动。我们有很强的理由相信这不会发生在镍同位素上，因此它们记录了小天体核心形成的强烈信号。虽然一些小行星的形成，如灶神星，被认为是很好的理解，但我们最近的伴星月球的起源长期以来一直存在问题。似乎成功的动力学模型未能解释其与地球的化学相似性。为了解决这个问题，一套新的模型已经提出，这代表了一个根本的偏离风格的形成。然而，人们仍然不知道月球实际上是如何从这种碰撞中形成的蒸汽云中形成的。这是我们第四个项目的重点，将进一步研究新模型是否也能解释地球和月球相同的同位素组成。地球内部很难探测，但月球内部的动力学更难。地球上使用地震技术，月球上也有一些地震记录。这些嘈杂的数据很难处理，但处理地面数据的进展使我们有时间重新检查月球档案中携带的信息。特别是，该项目将寻找各向异性-由物体的优先排列引起的。这在地球上被证明是非常成功的，可能会揭示月球内部运动的更详细的图片，以及这是否与表面的明显特征有关。最后，我们的行星探索集中在土星卫星泰坦的活跃大气层。利用航天器的光谱观测和新的高分辨率地面数据，该项目将研究土卫六大气中含氧分子的分布，并利用这些信息测试产生和移动这些物种的过程模型。这将为了解遥远行星体的活跃大气提供一个窗口。

The proposed work follows the development of planetary bodies from formation of their raw materials to the functioning of their atmospheres. Our attention starts with the earliest solar system, when the only fine grained material was present around the sun. We will both look at the distribution of a key radioactive nuclide in this nebula and the separation of gas from solid at the beginnings of planet formation. This will tell us about the compositions of planets likely to form and whether or not they will melt extensively. A major event in the history of a growing planet is the sinking of metal to its centre, forming a core. This is well understood on Earth, but not for smaller planetary bodies. We will use a novel, isotopic measure of the size of cores in one of the largest asteroids (Vesta), the Moon and Mars. This new approach is made possible by our ability to make precision isotopic measurements and couple them with melting experiments in the lab. The idea behind this approach is that we have few samples of these planetary bodies and the techniques used on Earth do not work well for such samples, which have experienced unknown perturbation en route to the surface. We have strong reason to believe this does not occur for Ni isotopes and so they record a robust signal of core formation in small bodies.Although the formation of some small planetary bodies, like Vesta, is thought to be well understood, the origin of our closest companion, the Moon has long proven problematic. What appeared successful models of its dynamics fail to account for its marked chemical similarity with the Earth. To address this a new suite of models have been proposed, which represent a radical departure in the style of formation. However, it is still not know how the Moon actually forms from the vapour cloud formed in such collisions. This is the focus of our fourth project which will further see if the new models can also explain the identical isotopic compositions of Earth and Moon.The interior of the Earth is difficult to probe, but the dynamics of the Moon's interior is yet harder. Seismic techniques are used on Earth and there are some seismic records of the Moon. These noisey data are difficult to process, but advances in processing terrestrial data make it time to re-examine the information carried in the lunar archive. In particular, the project will look for anisotropy- caused by the preferential alignment of objects. This has proven very successful on Earth and may reveal a more detailed picture of motions within the lunar interior and whether or not this relates to obvious features on the surface.Finally our planetary exploration focuses on the active atmosphere of Saturn's satellite Titan. Using spectroscopic observations from spacecraft and new, high-resolution, ground-based data, the project will examine the distribution of oxygen bearing molecules in Titan's atmosphere and use this information to test models of the processes that produce and move these species. This will provide a window into understanding the active atmosphere of a distant planetary body.