Flux and structure of meteoroids which impact the Earth

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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.