Planetary Science and Cosmochemistry at the University of Manchester

我们试图了解我们太阳系的不同环境是如何形成和演变的，以及它们今天是如何运作的。我们研究到达地球表面的样品（例如陨石）或由太空任务带回的样品。我们还利用对太阳系其他天体的观测，从中我们可以确定成分并推断火山活动和撞击坑的历史。我们将我们的数据与模型进行比较，例如模拟大气，小行星冷却和火山爆发的模型。这些模型是基于我们用来了解我们的星球的相同想法。因此，在了解太阳系的同时，我们也在测试自己的想法，并深入了解地球环境如何对自然和人为变化做出反应。包括地球在内的行星的组成是在45.6亿年前围绕成长中的太阳形成的尘埃和气体盘中确定的。尘埃颗粒团被瞬间加热成熔融液滴，然后迅速冷却：球粒。软骨球的形成除去了被热赶走的物质（“挥发物”，如水）。通过在实验室中制造“陨石球粒”并将其与陨石样品进行比较，我们将了解圆盘的组成，并试图确定加热机制（闪电，冲击波，撞击）。第一批小行星--微行星--是由球粒和其他颗粒形成的，其中一些从来没有热过。快速衰变的放射性加热了微行星，当微行星冷却时，它们被轰击，直到圆盘消散--这导致了更多的挥发性损失。通过研究来自这些微行星的陨石，我们将追踪加热、冷却和撞击过程的历史，以了解行星的初始成分，了解塑造早期太阳系的撞击，并了解放射性是否均匀地分布在圆盘中，或者是否有证据表明在太阳系形成时从附近的星星引入。有些陨石富含挥发物。我们将了解它们的挥发性成分是如何演变的，并测试它们是否代表了补充行星的来源。我们还将测试漂浮在我们大气层中的微小尘埃颗粒，看看它们是否采样了另一个来源，如彗星。我们将研究微生物是否可以在某些陨石中富含碳的物质上生存，以及这些物质是否可以作为地球以外生命的燃料。自从行星形成以来，它们的地壳已经被撞击、火山活动和水流所改变。撞击提供了一个可以改变岩石结构的热源-月球上的一些神秘岩石提供了研究这种情况如何发生的机会，并了解整个太阳系行星地壳演化的主要过程。月球的火山活动在覆盖在火山口周围的火山碎屑沉积物中很明显。利用这些火山中心的图像，以及从月球带回的火山岩的结构，我们将发现这些物质从月球内部被炸出的速度有多快。由于膨胀的气体为这种喷发提供了动力，这反过来将为月球内部挥发物的浓度提供见解。我们将研究最近发现的火星陨石，它似乎是由撞击组合而成的不同年龄的多个碎片。从这一点上，我们将了解火星表面的组成如何随着时间的推移而变化，以及这如何影响其大气层。行星大气层提供了一个令人兴奋的机会来测试我们用来了解我们自己的天气和气候的想法。火星表面显示了40亿年前的痕迹，当时它的气候非常像地球，我们将研究云如何形成并导致这种环境下的降水。在土星上，我们将通过模拟其北极周围六边形云结构的形成来测试我们对行星自旋如何与其大气相互作用的理解。

We seek to understand how our solar system's diverse environments formed and evolved, and how they operate today. We study samples that arrived at the Earth's surface (e.g. meteorites) or were brought back by space missions. We also use observations from missions to other bodies in our solar system, from which we can determine compositions and infer their history of volcanic activity and impact cratering. We compare our data to models, such as those that simulate atmospheres, the cooling of asteroids and volcanic eruptions. These models are based on the same ideas we use to understand our planet. So as well as learning about our solar system, we test our ideas and gain insight into how the Earth's environment responds to natural and man-made changes.The compositions of the planets, including the Earth, were set as they formed in a disk of dust and gas that circled the growing sun 4.56 billion years ago. Clumps of dust grains were flash-heated into melt droplets that rapidly cooled: chondrules. Chondrule formation removed species that are driven off by heat ("volatiles", like water). By making "chondrules" in the lab and comparing them to meteorite samples we will understand the composition of the disk and try to identify the heating mechanism (lightning, shock waves, impacts). The first asteroids - planetesimals - were formed from chondrules and other grains, some of which had never been hot. Fast-decaying radioactivity heated planetesimals, and as planetesimals cooled they were bombarded until the disk had dissipated - this led to more volatile loss. By studying meteorites from these planetesimals we will track the history of heating and cooling and impact processing to understand the starting compositions of planets, to characterise the impacts that shaped the early solar system, and to learn whether radioactivity was equally distributed in the disk or shows evidence of having been introduced from a nearby star as the solar system was forming.Some meteorites are rich in volatiles. We will learn how their volatile content evolved, and test whether they may represent a source that replenished the planets. We will also test minute particles of dust that float down through our atmosphere to see if they sample another source, such as comets. We will study whether microbes can live on carbon-rich material in some meteorites, and so whether this material could serve as fuel for life beyond Earth. Since the planets formed, their crusts have been modified by impacts, by volcanic activity, and by water flows. Impacts provide a source of heat that can change the structures of rocks - some enigmatic rocks on the Moon offer the chance to study how this occurs and learn about a major process in the evolution of planetary crusts across the solar system. Lunar volcanic activity is evident in the volcanic pyroclastic deposits that now drape the surface around volcanic vents. Using images of these volcanic centres, and the structure of volcanic rocks brought back from the Moon, we will find out how rapidly the material was blasted out of the lunar interior. Since expanding gases power such eruptions, this in turn will provide insights into the concentration of volatiles inside the Moon. We will examine a recently discovered Martian meteorite that appears to be multiple fragments of different ages assembled by an impact. From this we will learn how the composition of the Martian surface has changed over time, and how this has affected its atmosphere. Planetary atmospheres provide an exciting opportunity to test the ideas we use to understand our own weather and climate. The Martian surface shows traces of a time 4 billion years ago when it had a climate very like the Earth, we will study how clouds would form and lead to precipitation in this environment. On Saturn, we will test our understanding of how a planet's spin interacts with its atmosphere by modelling the formation of hexagonal cloud structures around its North Pole.