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Researchers from Imperial college London and the Russian Academy of sciences used specifically designed computer simulations to predict whether asteroids with a diameter up to one kilometre will explode in the atmosphere or reach the Earth’s surface. The results indicated asteroids greater than 200 metres in diameter have a larger probability of hitting the Earth than first expected.
The findings predict that many more asteroids will explode in the atmosphere than previous estimates, lowering the threat posed by impact related Tsunamis. The researchers suggests that Near Earth Object (NEO) monitoring institutions review their programs to search for smaller objects.
"There is overwhelming evidence that impacts from space have caused
catastrophes for life on Earth in the past, and will do so again. On Earth the atmosphere acts like a screen and geological activity erodes many craters too. Massive impacts of the type thought to have wiped out the dinosaurs leave an indelible print on the Earth, but we have not been able to accurately document the effect of smaller impacts. Now, we have a handle on the size of 'rock' we really need to worry about and how well the Earth's atmosphere protects us." Said Dr Phil Bland from Imperial’s Earth Science department.
The scientists created a new model of asteroids smashing into the Earth’s atmosphere, which included more accurate interaction between asteroids and the atmosphere. Over 1,000 simulations were completed with this new model and previously excepted old models. Objects made of either iron or stone, were used to reflect the composition of asteroids and experiments were run with varying diameters up to one kilometre.
The researchers found the number of impacts for iron objects were
comparable with all models, although for stone old models significantly
overestimated the probability of surviving atmospheric re-entry. The data suggests that stony asteroids need to be 1,000 times bigger than the iron ones to make similar sized craters.
The results are published in the 17 July issue of Nature.
More info: Nature
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