Flux and structure of meteoroids which impact the Earth

流星是了解早期太阳系的独特窗口。来自彗星和小行星的毫米大小的尘埃碎片变化很小，因为它们在行星形成之前从太阳星云中凝结出来，它们的结构和成分告诉我们我们自己行星的起源。这种大小范围的流星体也对航天器构成威胁，包括载人飞行任务。最慢的流星体的速度比子弹快得多，过去曾使航天器失去能力。 在西方大学，我们有一些世界上最先进的观测流星的仪器。有了这笔资金，我们将研究流星撞击地球的速度分布;这将告诉我们大多数流星体来自哪里，以及它们对航天器的危险程度。 我们还将使用雷达和流星照相机来观察流星雨活动，以便我们能够更好地预测何时可能发生壮观（和潜在危险）的爆发。通过将这些流星与它们的母体联系起来，我们可以更好地了解地球附近彗星和小行星的近代历史。不属于流星雨的流星可能有数万年或数十万年的历史，这给了我们一个了解我们附近彗星和小行星过去活动的窗口。这些小物体也比流星雨多得多，因此对航天器构成最大的风险。我们将看看这些流星的活动如何随时间变化。 我们的流星相机可以跟踪流星，因为他们飞在天空中使用非常快的镜子和望远镜。这些流星中的一些在飞行时粉碎成尘埃，一些破碎成几大块，还有一些似乎根本没有破碎。从它们在大气中燃烧时的分解方式，我们可以知道流星体的组成颗粒是如何粘在一起的;光谱信息可以缩小哪些矿物可能是单个流星体的一部分。我们将建立流星体在大气中蒸发之前几分之一秒内发生的事情的模型：这将帮助我们了解母小行星和彗星是由什么组成的，以及它们是如何形成的。我们还可以计算出流星体的物理特性，这有助于评估它们在碰撞中的危险程度。

Meteors are a unique window into the early solar system. Millimeter-sized pieces of dust from comets and asteroids have changed very little since they condensed out of the solar nebula before the planets formed, and their structure and composition tell us about the origin of our own planet. Meteoroids in this size range also pose a threat to spacecraft, including crewed missions. The slowest meteoroids travel much faster than bullets and have incapacitated spacecraft in the past. At Western University, we have some of the most advanced instruments in the world for observing meteors. With this grant, we will study the distribution of speeds at which meteors strike our planet; this will tell us where most meteoroids come from as well as how dangerous they are to spacecraft. We will also look at meteor shower activity, using both radar and meteor cameras, so that we can better predict when spectacular (and potentially dangerous) outbursts may occur. By linking these meteors with their parent bodies, we can better understand the recent history of comets and asteroids near the Earth. Meteors which don't belong to showers may be tens or hundreds of thousands of years old, and give us a window into the past activity of comets and asteroids in our neighbourhood. These small objects are also much more numerous than shower meteors, and so pose the most risk to spacecraft. We will look at how the activity of these meteors changes with time. Our meteor cameras can track meteors as they fly across the sky using very fast mirrors and a telescope. Some of these meteors crumble into dust as they fly, some break into a few large pieces, and some seem not to break apart at all. From the way they break apart as they burn up in the atmosphere, we can tell how the component grains of meteoroids are stuck together; spectral information can narrow down which minerals might be part of individual meteoroids. We will build up models of what happens to a meteoroid in the fraction of a second before it is vaporized in the atmosphere: this will help us understand what the parent asteroids and comets are made of, and how they formed. We can also work out physical properties of the meteoroids, which help to evaluate how dangerous they will be in a collision.