Anewgeneration of cosmic dust is continuously produced and processed through the evolution of stars and planetary systems, as observed in stellar atmospheres, debris disks, and the solar system.
Even though nearly all of the truck-size spacecraft would burn up in the atmosphere, some debris could survive and be dangerous, as in the case of a Soviet satellite that scattered wreckage over the Northwest Territories in Canada.
Christopher Kraft, the former head of Nasa's Manned Spaceflight Centre, one of the authors of the letter, warned of a "catastrophic re-entry" of the 400-tonne station into the Earth's atmosphere and showers of debris if there was no capability to fix it in the event of a "terrible failure".
The disaster agency said it had spewed millions of cubic meters of debris into the atmosphere.
On July 11 , 1979 it entered the atmosphere, broke up, and scattered debris over the southeastern Indian Ocean and Western Australia.
The disaster agency said it had spewed millions of cubic metres of debris into the atmosphere.
This theory states that the impact of an asteroid on Earth may have triggered the extinction event by ejecting a huge quantity of rock debris into the atmosphere, enshrouding Earth in darkness for several months or longer.
Russian officials have also suggested that the 13-ton probe, which fell out of orbit and burned up in the atmosphere on Sunday, scattering some debris over the Pacific Ocean, might have been struck by an anti-satellite weapon.
This theory states that a bolide (meteorite or comet) impact may have triggered the extinction event by ejecting a huge quantity of rock debris into the atmosphere, enshrouding Earth in darkness for several months or longer.
But officials of the National Aeronautics and Space Administration feared that one more failure by navigation instruments would leave the huge $670 million spacecraft uncontrollable and, on its re-entry into the atmosphere, a threat to scatter debris over populated areas.
