by Mitchell Zimmer
Thanks to the Distinguished Research Professorship, Professor Peter Brown of the Deaprtment of Physics & Astronomy will follow up on a once in a lifetime chance that fell from the sky.
Soon after a meteor exploded over the Russian city of Chelyabinsk on February 15, the Canada Research Chair in Meteor Science was part of a worldwide team to provide an immediate analysis of the fireball. “The first month was very frantic,” says Brown, “now we’re settling down more into the detailed analysis which I find more enjoyable.”
The Distinguished Research Professorship releases Brown from his teaching duties for one year so that he can pursue these new avenues of inquiry. There are several different areas to investigate about this phenomenon and he is involved either in a leadership role or a support role in most of them. “We have put out, based on a lot of initial analysis, some information. Of course people are very interested in this, but we’re trying to do more detailed information, looking at refining the orbit and trajectory.”
Brown says that the size of the meteorite was worked out quite early on. “Our much more detailed analysis has basically borne out those initial estimates. It was about twenty metres across and had the equivalent energy of about half a ton of TNT.” The analysis did reveal at least one surprise. “From my perspective the most unusual aspect of this was the shock wave which was very strong and damaged thousands of windows in the city” says Brown. “I’m spending more than fifty per cent of my time trying to understand the damage assessment from that air blast.”
Another big question is how large an asteroid needs to be before it hits Earth. “That’s what we want to understand, our models suggest that stony objects, like those at Chelyabinsk, really start producing damage on the ground once they get into the 40, 50, 60 meter size - how big do you need to be before you worry about things on the ground?” The Chelyabinsk event gives researchers like Brown a much needed opportunity to fill in some gaps in their data. “This is a huge windfall for us to understand all of these things in a natural laboratory. Something like this object hits the earth maybe once every eighty years, an object of this size or bigger hits near an urban area like Chelyabinsk once in every 4,000 years” says Brown. “For it to happen so close to a city is really unusual and so it gives us a great opportunity to dig, in detail, on how these things happen at sizes much larger than we have seen before. This is a totally unique event.”
The next year will have Brown traveling to meet with other researchers who are trying to understand what the damage mechanisms in play from meteors are. He estimates that within the next few decades objects smaller than Chelyabinsk, will actually be detected before they impact. “The question will be, ‘What do you do?’” Brown then adds, “If we had known about Chelyabinsk beforehand, with the information we have at hand now, we probably could argue that it may have been worthwhile to evacuate there, because you couldn’t be absolutely certain what the shock wave would do and that probably would have reduced the number of injuries. We want to be more informed and this information will come back to play in a practical way in the next few decades as our asteroid survey starts to pick up.”