From: Near Earth Object Information Centre
Posted: Friday, March 21, 2003
Today at the Lunar and Planetary Science Conference in Houston Dr Jim Head presented new results to suggest that about one rock from Mars falls on Earth each month. Headís work involves calculating exactly how often asteroids and comets impact with the planet Mars and how many martian rocks these collisions blast up into space. He then models the paths of these little fragments of the red planet, under the influence of the combined gravity of the planets and Sun to see how many and how often such martian meteorites fall to Earth.
The results of the new research suggest that martian meteorites come from craters larger than 3 km on the red planet and take up to 100 million years to make the 45 million kilometre journey to the Earth. Headís work implies that the currently known martian meteorites, of which there are just over 20, come from around 6 craters on the martian surface and so some are samples of closely related rocks that can give additional clues to the geological history of the red planet.
Martian meteorites are our only samples of another planet and they provide us with the opportunity of to investigate how planets form and evolve in general. It is only because of the collision of asteroids and comets with Mars, every few hundred thousand years, that we can study the red planet in such detail.
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