I have written about using space rocks as weapons.
Robert A. Metzger had performed a calculation that a civilization with access to 100 to 1000 times the energy that we have now (possible with advanced nanotechnology) could make 1000 big particle accelerators and over a year slow planet earth down enough to dodge teh incoming asteroid
Of course the space rock as weapon with an advanced adversary could make some adjustments, but being able to dodge does raise the bar. Plus it shows that a really advanced civilization with a lot of power can handle any size natural asteroid if it spots it within 2 years.
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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