"BEIJING, July 7 (Reuters) - Chinese researchers want to send more than 20 of China's largest rockets to practice turning away a sizable asteroid - a technique that may eventually be crucial if a killer rock is on a collision course with Earth.
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At China's National Space Science Center, researchers found in simulations that 23 Long March 5 rockets hitting simultaneously could deflect a large asteroid from its original path by a distance 1.4 times the Earth's radius.
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The science center cited a recently published study in Icarus, a journal on planetary science.
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The proposal of keeping the upper stage of the launch rocket to a guiding spacecraft, making one large 'kinetic impactor' to deflect an asteroid, is a rather nice concept," said Professor Alan Fitzsimmons from the Astrophysics Research Centre at Queen's University Belfast.

"By increasing the mass hitting the asteroid, simple physics should ensure a much greater effect," Fitzsimmons told Reuters, although, he added, the actual operation of such a mission needs to be studied in greater detail.
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Altering an asteroid's path presents a lower risk than blasting the rock with nuclear explosives, which may create smaller fragments without changing their course, scientists say."

https://www.reuters.com/lifestyle/science/chinese-researchers-propose-deflecting-armageddon-asteroids-with-rockets-2021-07-07/