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Investigating the Solar System with Isotope Cosmochemistry

用同位素宇宙化学研究太阳系

基本信息

批准号：
ST/G003068/1
负责人：
Ian Lyon
金额：
$ 357.57万
依托单位：
University of Manchester
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2009
资助国家：
英国
起止时间：
2009 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FG003068%2F1
关键词：
Investigating Solar System Isotope Cosmochemistry

项目摘要

We focus on the prehistory, formation and evolution of our solar system, to understand whether planets like our Earth, capable of supporting life, are common. To do this we pioneer new technology and apply it to samples of extraterrestrial material, notably samples from space missions and meteorites, (fragments of planets and asteroids that reach the Earth). Our solar system formed by collapse of a cloud of dust and gas in interstellar space. We can find out what our sun's parent cloud was like by studying presolar grains - particles of dust from the cloud that have been preserved inside meteorites. Each grain formed around a dying star, so they reveal the history of the galaxy before our sun formed and how the elements of our everyday world were made in previous generations of stars. They also experienced shocks from exploding stars as they floated through galactic space. Comparing these grains with those entering the solar system today (returned by the Stardust mission) will let us to see how galactic dust has changed over the last 5 billion years. We also study our sun's birth place through traces of radioactive decay preserved in meteorites. The decay occurred so quickly that radioactive material must have been made shortly before the sun began to form, so the sources - massive stars - must have died nearby relatively recently. From these traces we learn how the stars made material and how it was mixed into their surroundings. This radioactive decay in the early solar system also lets us measure the time between events as asteroids and planets formed. In meteorites we have snapshots of stages in the life of the first asteroids that tell us how long it took them to grow, heat up, form cores and rocky mantles, and cool. Material that the Stardust mission returned will tell us if comets played a major role in providing our Earth with volatiles. Volatiles (things that condense at low temperature, like water) are essential for life, and meteorites let us understand how they behaved on the first asteroids. The sun's mass dominates the solar system, so it defines the bulk composition. The Genesis mission returned a solar wind sample, allowing us to measure this composition and so tell where the Earth's varies. This will also help us understand how our planet grew in its current form. We know planets incorporated volatiles into their interiors - on Earth and Mars volcanoes have released massive amounts of CO2 into the atmosphere. But when rocks are heated or melted as a planet forms they ought to lose volatiles very quickly, so why do planetary interiors contain any volatiles at all? There are two ideas. Some people think volatiles dissolved into a molten planetary surface from a massive early atmosphere that had been captured by gravity, others that volatiles trapped in the material from which the planet was built could not escape easily. Neon can act as a fingerprint that will allow us to identify the culprit, once we have understood the neon composition trapped in meteorites. The story wasn't complete once planets were assembled. Terrestrial planets like our Earth have been affected by many processes since they formed. These processes can be studied through the traces they have left on samples such as meteorites from Mars and the Moon. By studying martian meteorites we can understand the timing of fluid flows on the martian surface and what sort of environment these fluids had come from. In particular, we can compare them with terrestrial fluids and seek evidence of the effects of life. By looking at lunar samples we can supplement the information gained from the Apollo missions and better understand the massive cratering events and volcanic processes that shaped the familiar face of the full Moon.

我们专注于太阳系的史前史，形成和演化，以了解像我们地球这样能够支持生命的行星是否常见。为了做到这一点，我们开创了新技术，并将其应用于外星物质的样本，特别是来自太空任务和陨石的样本，（到达地球的行星和小行星的碎片）。我们的太阳系是由星际空间中的尘埃和气体云坍缩形成的。我们可以通过研究前太阳颗粒来找出太阳的母云是什么样子的--前太阳颗粒是保存在陨石中的云尘颗粒。每一颗颗粒都是围绕着一颗垂死的星星形成的，因此它们揭示了太阳形成之前银河系的历史，以及我们日常世界的元素是如何在前几代恒星中形成的。当他们漂浮在银河系空间时，他们也经历了恒星爆炸的冲击。将这些颗粒与今天进入太阳系的颗粒（由星尘使命返回）进行比较，将让我们看到银河系尘埃在过去50亿年中的变化。我们还通过陨石中保存的放射性衰变痕迹来研究太阳的诞生地。衰变发生得如此之快，以至于放射性物质一定是在太阳开始形成前不久产生的，所以这些放射源--大质量恒星--一定是在相对较近的时间内死亡的。从这些痕迹中，我们了解到恒星是如何制造物质的，以及物质是如何与周围环境混合的。早期太阳系中的这种放射性衰变也让我们能够测量小行星和行星形成的时间间隔。在陨石中，我们有第一批小行星生命阶段的快照，告诉我们它们花了多长时间成长，加热，形成核心和岩石地幔，冷却。星尘使命返回的材料将告诉我们彗星是否在为我们的地球提供挥发物方面发挥了重要作用。挥发物（在低温下凝结的东西，如水）对生命至关重要，陨石让我们了解它们在第一颗小行星上的行为。太阳的质量决定了太阳系的整体组成。“创世纪”使命返回了一个太阳风样本，使我们能够测量这种成分，从而告诉我们地球的变化。这也将帮助我们了解我们的星球是如何以目前的形式成长的。我们知道行星将挥发物融入其内部-在地球和火星上，火山向大气中释放了大量的二氧化碳。但是，当岩石在行星形成时被加热或熔化时，它们应该会很快失去挥发物，那么为什么行星内部会含有挥发物呢？有两个想法。有些人认为挥发物从被引力捕获的大量早期大气中溶解到熔化的行星表面，其他人认为挥发物被困在建造行星的材料中无法轻易逃脱。氖可以作为指纹，一旦我们了解了陨石中的氖成分，就可以识别出罪魁祸首。一旦行星被组装起来，这个故事就不完整了。像我们地球这样的类地行星自形成以来一直受到许多过程的影响。这些过程可以通过它们在火星和月球陨石等样品上留下的痕迹来研究。通过研究火星陨石，我们可以了解火星表面流体流动的时间以及这些流体来自什么样的环境。特别是，我们可以将它们与陆地流体进行比较，并寻找生命影响的证据。通过观察月球样本，我们可以补充从阿波罗任务中获得的信息，并更好地了解塑造满月熟悉面孔的大规模陨石坑事件和火山过程。