Why is this Important?

In the early 1980's, Drs Louis and Walter Alverez postulated that the dinosaurs died out because of a meteroite strike from an exterrestrial blow. A creater was later discovered in the Yucatan penninsula at what is now called chicxulub. He found a rare chemical called iridium, which is associated with meteorites, in the geological strata known for the demise of the dinosaurs. This was found in locations throughout the world. Walter Alverez has yet to received the Noble prize for his work. Since that time over 150 meteorite strikes have been found on land and offshore.
It is postulated that an asteroid or comet over 1 kilometer would produce a worldwide cloud of dust known as an impact winter. This would destroy all crops for at least one season. If this strike was in the water, which makes up 2/3 of our earth, then there would be a major tsunami that would destroy the coastlines of the oceans' continents that surround the strike zone. A large exterresteral body could produce earthquakes and firestorms that would destroy civilization as we know it.

Here is an excellent link from the Soutwest Research Institute on NEO defense : http://www.boulder.swri.edu/clark/neowp.html

In 1994 Levy-Shoemaker 9, a long-term comet, crashed into Jupiter after being captured by that planet and breaking into 21 pieces. This motiovated Congress to task NASA with the job of finding and tracking all NEO Asteroids over 1 kilometer in size. NASA has tasked themselves to find 90% of these Asteroids by 2008. Here is what about.com has to say about this problem: http://space.about.com/cs/nasanews/a/neoimpact.htm