And they are right. We just don't know when. Grant Program to help find out the answer. The purpose of the program is to enable new discoveries of asteroids known to be in our planet's vicinity. The Society funds for the NEO Grant Program come from its 100,000 members worldwide, whose voluntary dues and donations permit targeted support to research and development programs.
Earth lives in a swarm of near-Earth objects of different sizes and orbits.
The results of those impacts are seen graphically on the crater-marked surfaces of Mercury, the Moon, Mars and the outer planet satellites. Because of Earth's oceans, the heavy atmospheric processes, and the modifications to the surface of the planet by life itself, such craters are less visible on Earth. Less than 200 NEOs have been discovered thus far. It is estimated there are several thousand such NEOs larger than one kilometer and 150,000 to perhaps 100 million larger than 100 meters in size. While various astronomical groups and NASA advisory committees have made strong recommendations to accelerate discovery of these asteroids, government support for NEO search programs is very modest.