An Introduction to Planetary Defense antonis English April 29, 2007March 25, 2008 1 Minute A group of American aerospace engineers have written a book on how to defend the earth against alien invasion. A limited preview can be found here. [ref] Share this:TwitterFacebookEmailLike this:Like Loading... Published by antonis View all posts by antonis Published April 29, 2007March 25, 2008
