A journey from the solar nebula to planetary bodies: cycling of heat, water and organics

在这个研究项目中，来自格拉斯哥大学和苏格兰大学环境研究中心的行星科学家和工程师们联手回答了有关小行星、月球和火星的起源和演化的重要问题。我们的工作重点是了解这些行星体在一定时间和距离尺度上的热历史，以及水和富含碳的分子如何在它们内部和之间运输。该联盟的一部分将探索小行星的形成和后来的历史。我们的重点是原始小行星，它们自45亿年前在被称为太阳星云的尘埃和气体云中形成以来几乎没有变化。这些天体比行星小得多，但在科学上非常重要，因为它们含有水和富含碳的分子，这两者都是生命所必需的。我们想要了解形成这些小行星的所有物质，以及它们来自太阳星云的哪里。虽然它们非常原始，但这些小行星中的大多数都是由液态水驱动的化学反应改变的，液态水本身是由冰融化产生的。我们会问，融化这些冰所需的热量是由放射性元素的衰变产生的，还是由与其他小行星的碰撞产生的。这个问题的答案对于理解所有类型的小行星是如何进化的，以及当我们收集原始小行星的样本并返回地球时，我们可能会发现什么，具有重要的意义。原始小行星的碎片也会以陨石的形式落到地球上，并带来一些原始的水，以及富含碳的分子。许多科学家认为，今天地球上的大部分水是从外太空获得的，联合研究人员想要验证这一想法。为了了解陨石可能带来的水和碳的性质和体积，我们首先需要开发可靠的方法来区分地外碳和水与陨石坠落地球后添加到陨石中的碳和水。我们计划通过识别地球水和碳的“指纹”来做到这一点，这样它们就可以从地球外的成分中减去。在地球形成初期，碳被传递到地球的主要方式之一是大型陨石以高速撞击地球表面。因此，我们也希望了解在这些高能撞击事件中，地外碳被保存或转化的程度。月球的形成和早期热历史是该联盟感兴趣的另一个领域。特别是，我们将询问它的岩石外壳是什么时候形成的，并利用它的撞击历史来确定整个内太阳系的陨石通量。为了回答这些问题，我们将分析阿波罗和月球任务收集的陨石和样本，以确定这些岩石中含有的化学元素的数量，包括氩和铅。关于火星表面和地下区域温度的信息可以帮助我们了解包括火星地壳与液态水相互作用在内的过程。为了能够利用NASA InSight着陆器即将获得的火星岩石热特性信息来探索这些过程，我们将对模拟火星表面的加热和冷却效果进行实验室研究。从火星内部到达火星表面的热水可能曾经创造了适合生命发展的环境，由这些水形成的矿物质可能保存了当时存在的任何微生物的痕迹。我们将通过研究地球上一个独特的高海拔温泉系统来评估这种温泉保存过去火星生命痕迹的可能性。

In this research programme, planetary scientists and engineers from the University of Glasgow and the Scottish Universities Environmental Research Centre have joined forces to answer important questions concerning the origin and evolution of asteroids, the Moon and Mars. The emphasis of our work is on understanding the thermal histories of these planetary bodies over a range of time and distance scales, and how water and carbon-rich molecules have been transported within and between them.One part of the consortium will explore the formation and subsequent history of asteroids. Our focus is on primitive asteroids, which have changed little since they formed 4500 million years ago within a cloud of dust and gas called the solar nebula. These bodies are far smaller than the planets, but are scientifically very important because they contain water and carbon-rich molecules, both of which are essential to life. We want to understand the full range of materials that went to form these asteroids, and where in the solar nebular they came from. Although they are very primitive, most of these asteroids have been changed by chemical reactions that were driven by liquid water, itself generated by the melting of ice. We will ask whether the heat needed to melt this ice was produced by the decay of radioactive elements, or by collisions with other asteroids. The answer to this question has important implications for understanding how asteroids of all types evolved, and what we may find when samples of primitive asteroids are collected and returned to Earth. Pieces of primitive asteroids also fall to Earth as meteorites, and bring with them some of their primordial water, along with molecules that are rich in carbon. Many scientists think that much of the water on Earth today was obtained from outer space, and consortium researchers would like to test this idea. In order to understand the nature and volume of water and carbon that would have been delivered by meteorites, we first need to develop reliable ways to distinguish extraterrestrial carbon and water from the carbon and water that has been added to the meteorite after it fell to Earth. We plan to do this by identifying 'fingerprints' of terrestrial water and carbon so that they can be subtracted from the extraterrestrial components. One of the main ways in which this carbon was delivered to Earth during its earliest times was by large meteorites colliding with the surface of our planet at high velocities. Thus we also wish to understand the extent to which the extraterrestrial carbon was preserved or transformed during these energetic impact events.The formation and early thermal history of the moon is another area of interest for the consortium. In particular, we will ask when its rocky crust was formed, and use its impact history to determine meteorite flux throughout the inner solar system. To answer these questions we will analyse meteorites and samples collected by the Apollo and Luna missions to determine the amounts of chemical elements including argon and lead that these rocks contain. Information on the temperature of surface and sub-surface regions of Mars can help us to understand processes including the interaction of the planet's crust with liquid water. In order to be able to explore these processes using information on the thermal properties of martian rocks that will soon to be obtained by the NASA InSight lander, we will undertake a laboratory study of the effects of heating and cooling on a simulated martian surface. Hot water reaching the surface of Mars from its interior may once have created environments that were suitable for life to develop, and minerals formed by this water could have preserved the traces of any microorganisms that were present. We will assess the possibility that such springs could have preserved traces of past martian life by examining a unique high-altitude hot spring system on Earth.