The impact diaries
The team
Mike Bullivant's diary about the challenge for the Impact programme, from the BBC/OU series Rough Science 4
Day One & Two
If someone had told me that you can estimate the size of the meteor that created a particular impact crater just by dropping a 1.75 kilo steel ball into sand, I’d have told them they were talking rubbish. But it can be done. The first two days of this challenge involved me doing just that. For this programme, Kathy, Iain and I have been given the job of working out the size (diameter) of the meteorite that produced the particularly large impact crater in the Nevada Desert. While Kathy and Iain were away in Nevada working out the actual size of the crater, my job was to create a series of much smaller craters using a much smaller meteorite.
All I had to do was drop a steel ball of known weight from known heights and plot the diameter of the impact craters that I formed against the energy of the impact, which can be calculated since you know the height from which you’re dropping the ball. By going to greater and greater heights you can get more and more impact energy. From just a few data points, it’s possible to estimate the size of the meteorite that will produce a particular crater size. The idea is to extrapolate from my small-scale results to the larger scale of the Nevada crater.
OK, there are other processes going on in real meteorite impacts, such as the meteorite exploding – something that we could never reproduce experimentally under Rough Science conditions. Even so, this extrapolation method might still work well enough for our purposes.
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Content last updated: 19/07/2006
