Asteroid fragments on a fast collision courseOver a million large asteroids, each several kilometres wide, are orbiting the Sun in a belt between Mars and Jupiter. There are sometimes violent collisions... Collisions in the Asteroid Belt result in the asteroids being completely destroyed and shattered into countless pieces. Computer simulations predict that most of these fragments will eventually fall into the Sun. Some of them, however, will hit the Earth after millions of years as meteorites... Collisional fragments from asteroids in space are constantly being hit by cosmic radiation. This creates noble gases from nuclear reactions. These gases do not enter into any further chemical reactions. Therefore, during the entire duration of the radiation, i.e., the travel time of the fragment in space, they accumulate in the fragment. After measuring the concentration of these so-called cosmogenic inert gases, the travel time from original body to Earth can be calculated. The higher the concentration, the longer the meteorite was underway... The researchers used meteorites for their tests that are assumed to be the results of a huge asteroid collision in the recent history of the solar system. These meteorites were found in a stone quarry in southern Sweden in a 480 million year old seabed deposit... With the new method, it could be proven for the first time that the noble gases in the meteorites in southern Sweden were already in the meteorites 480 million years ago. The calculated travel time was reduced to a few hundred thousand years, which corresponds to the lower limits predicted by the computer simulations. These were the first fragments to arrive on Earth after a great collision. The short radiation age is a clue that the collision took place in the proximity of an orbital resonance in the Asteroid Belt. In addition, it could be proven that the fossil meteorites from southern Sweden all stem from the same event. The newly developed method from the Institute for Isotope Geology makes it possible to confirm the theories about the behaviour of asteroid fragments in space. This will make it significantly easier for researchers to predict future collisions with our planet.
Philipp Reza Heck
Prof. Rainer Wieler
July 14, 2004
Long-Destroyed Fifth Planet May Have Caused Lunar Cataclysm, Researchers Say
SPACE dot COM | 18 March 2002 ,posted: 03:00 pm ET | By Leonard David, Senior Space Writer
Posted on 03/25/2002 5:42:10 PM EST by vannrox
http://www.freerepublic.com/focus/f-news/653287/posts
