Abstract This paper discusses the asteroid which scientists believe caused the extinction of dinosaurs and the probability of another event such as this occurring. It also discuss the measurements government has taken to prevent a damaging impact and the different methods they will use to deter such an asteroid if one should come too near the Earth.
From the Paper "Luckily for us, impacts that would cause massive destruction occur on Earth only about once ever 100,000 years (NASA Ames Space Science Division). According to NASA, these dangerous asteroids capable of wreaking global havoc are extremely rare."