Planetary Origins and Evolution at Imperial (2019-2022)

恒星和行星系统是如何发展的，生命是我们星球独有的吗？这是科学中最基本的问题之一，对我们在宇宙中的位置有着深远的影响。因此，这是科学和技术设施理事会设定的一项关键科学挑战。我们的地球是在45亿年前与太阳以及太阳系中的其他行星和小天体一起形成的。只有了解了太阳系形成的细节，我们才有希望找到答案。我们现在知道恒星和行星系统是如何形成的。我们知道恒星是由星际尘埃云和气体云的坍缩形成的，行星是由围绕在这些年轻恒星周围的尘埃云和气体云组成的。然而，对于太阳系是如何形成的，我们所知甚少。例如，为什么所有的行星都如此不同？为什么金星是地狱，火星是冰冻的岩石，而地球是生命的天堂？答案在行星聚集之前的事件中。我们的研究计划侧重于回答太阳系早期历史中关键的突出问题。太阳系前尘埃的来源为我们的太阳系提供了一个背景。尘埃来自于哪种类型的恒星，这种混合物是其他行星系统的典型特征吗？其中一些尘埃仍然保存在古老的陨石中，这表明至少有30颗恒星为我们的行星提供了基石。我们的目标是通过在地球历史上积累的沉积物中寻找保存在地球表面的星际尘埃，对更多的恒星进行取样。这将为行星系统提供一个完整的成分表，而不仅仅是我们自己的。在尘埃聚集成更大的天体后，行星物质的变化对制造适合生命生存的行星至关重要。我们的研究将通过检查陨石中早期磁场的证据，来检验行星的早期前身——原始的星子是否在内部熔化和混合。我们的研究将评估已经在陨石矿物中发现的古代磁性痕迹是否是金属岩心发电机的可靠指标。挥发性成分对生命至关重要，但很容易因加热而流失，而且在太阳系的不同行星之间，挥发性成分的含量差别很大。我们的研究重点是类地行星的挥发性预算，以确定挥发性预算的来源，并确定它们是何时添加的。为此，该研究检查了硒和碲的同位素，并通过技术和方法的进步使其成为可能，这将是该研究的先驱。因此，这项工作将帮助我们了解行星是如何获得形成生命所必需的成分的。在早期太阳系中，大量的挥发物、有机物和能量在长时间的剧烈轰击中被输送到类地行星上，这可能对生命的出现和进化产生了深远的影响。在月球、火星、金星和大型小行星上留下的大陨石坑提供了这种轰击的记录，但这一记录很难破译。通过使用先进的数值模型模拟大型陨石坑的形成，我们的目标是将观察到的陨石坑数量与形成它们的撞击物联系起来，并限制它们向太阳系内部传递的时间和来源。最后，什么构成了一颗“适合生命”的行星？迄今为止，已知只有地球上有生物。虽然在火星上寻找生命的工作仍在继续，但许多人认为，有生命的有机体更有可能存在于木星和土星卫星上被冰雪覆盖的海洋中。我们的研究将集中在利用实验和世界领先的分析技术来识别大气中生命的分子特征和冰卫星的流出物。这项研究可能会提供第一个令人信服的证据，证明地球外存在生命，并扩大我们对行星类型的认识。

How do stars and planetary systems develop and is life unique to our planet? This is one of the most fundamental of questions in science and has deeply profound implications for our place in the cosmos. It is thus a key scientific challenge set by the Science and Technology Facilities Council. Our planet formed 4.5 billion years ago along with the Sun and the other planets and minor bodies in our Solar System. Only by understanding the details of how our Solar System formed can we hope to find an answer.We now know how stars and planetary systems form in general. We know that stars form by the collapse of interstellar clouds of dust and gas, and planets are constructed in disks of dust and gas surrounding these young stars. There is, however, much we don't know about how our Solar System formed. Why, for example, are all the planets so different? Why is Venus an inferno, Mars a frozen rock, and Earth a haven for life? The answer lies in events that predated the assembly of the planets. Our research program focuses on answering key outstanding questions in this early history of the Solar System.The source of presolar dust provides a context to our solar system. From what types of star was dust derived and is this mixture typical of other planetary systems? Some of this dust still remains preserved within ancient meteorites and reveals that at least 30 stars produced building blocks for our planets. We aim to sample many more stars by looking for interstellar dust preserved on the Earth's surface within sediments accumulated throughout our planet's history. This will provide a full ingredient list for planetary systems, not just our own.How planetary materials changed after the dust was assembled into larger bodies is crucial in making planets that are suitable for life. Our research will examine whether primitive planetesimals, the early forerunners of planets, melted and mixed internally by examining the evidence for early magnetic fields within meteorites. Our research will evaluate whether ancient magnetic traces already found in meteorite minerals are reliable indicators of the dynamos of metallic cores.Volatile constituents are vital to life but easily lost by heating and they differ greatly in abundance between planets in our solar system. Our research focuses on the volatile budgets of the terrestrial planets, to identify the source of the volatiles and determine when they were added. For this, the research examines the isotopes of selenium and tellurium and is made possible by technology and method advances that will be pioneered in the study. As such, the work will help us understand how planets acquire the ingredients essential to the formation life.Large quantities of volatiles, organic matter and energy, were delivered to the terrestrial planets in a prolonged period of intense bombardment in the early solar system, which likely had a profound influence on the emergence and evolution of life. Large craters that scar the Moon, Mars, Venus and large asteroids provide a record of this bombardment, but one that is challenging to decode. By simulating large crater formation using advanced numerical models, we aim to link observed crater populations to the impactors that formed them and constrain the timing and source of their delivery to the inner solar system.Finally, what constitutes a planet "suitable for life"? To date only Earth is known to have living things. Whilst the search for life on Mars continues, many believe that living organisms are more likely within the ice-covered oceans of the moons of Jupiter and Saturn. Our research will focus on recognizing the molecular signature of life within the atmospheres and outflows from icy-moons using experiments and world-leading analytical techniques. This research could provide the first convincing evidence for life beyond Earth and widen our view of the right kind of planet.