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刻的影响。因此，这是科学和技术设施理事会设定的一个关键科学挑战。我们的星球与太阳以及太阳系中的其他行星和小天体一起形成于45亿年前。只有了解太阳系如何形成的细节，我们才有望找到答案。我们现在大体上知道了恒星和行星系统是如何形成的。我们知道，恒星是由星际尘埃和气体云坍塌形成的，行星是由尘埃和气体组成的圆盘环绕着这些年轻的恒星。然而，关于我们的太阳系是如何形成的，我们还有很多不知道的东西。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？答案就在行星聚集之前的事件中。我们的研究计划集中于回答太阳系早期历史中的关键悬而未决的问题。太阳系前尘埃的来源为我们的太阳系提供了一个背景。尘埃来自哪种类型的恒星？这种混合物是其他行星系统的典型吗？其中一些尘埃仍然保存在古老的陨石中，揭示出至少有30颗恒星为我们的行星制造了积木。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来采样更多的恒星。这将为行星系统提供一个完整的成分清单，而不仅仅是我们自己的。尘埃组装成更大的天体后，行星材料发生了怎样的变化，对于制造适合生命的行星至关重要。我们的研究将通过考察陨石中早期磁场的证据，来检验行星的早期先驱--原始小行星是否在内部融化和混合。我们的研究将评估已经在陨石矿物中发现的古代磁迹是否是金属核心发电机的可靠指示器。挥发性成分对生命至关重要，但很容易因加热而丢失，而且在我们太阳系的行星之间，它们的丰度差异很大。我们的研究重点是类地行星的不稳定预算，以确定挥发物的来源并确定它们何时被添加。为此，这项研究检查了硒和碲的同位素，这项研究的技术和方法进步将使这项研究成为可能。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。在太阳系早期的一段长时间的强烈轰炸中，大量的挥发物、有机物和能量被输送到类地行星，这可能对生命的出现和演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伤痕的大型陨石坑记录了这种轰炸，但这是一种难以破译的记录。通过使用先进的数值模型模拟大型陨石坑的形成，我们的目标是将观测到的陨石坑数量与形成它们的撞击器联系起来，并限制它们向内太阳系输送的时间和来源。最后，是什么构成了一个适合生命的行星？到目前为止，我们只知道地球上有生物。虽然在火星上寻找生命的工作仍在继续，但许多人认为，在木星和土星卫星的冰层覆盖的海洋中，更有可能存在生命有机体。我们的研究将集中于利用实验和世界领先的分析技术来识别大气层内生命的分子特征和从冰卫星流出的生命。这项研究可能会为地球以外的生命提供第一个令人信服的证据，并拓宽我们对合适的星球类型的看法。

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.