Astronomers say they are close to his goal — to find every asteroid that poses a threat to human civilization. The next challenge will be to find smaller objects that can destroy, for example, the city, the experts told the Subcommittee on Science, Technology and Space of the Senate of the United States. They're going to find all the objects more than a kilometer radius approaching the Earth. According to Lindley Johnson of NASA, to date, scientists have found about 70% of the "population" of asteroids with a diameter of a kilometer or more.
Specialists have little doubt that in the past many times asteroid slammed into the planet. For example, one or more of these stones were most likely the cause of death of the dinosaurs. But, as scientists believe, these events do not occur more than once every 700,000 years. However, they do not want to sit around, a reminder that the consequences of a collision with an asteroid can be so devastating that the defense simply need to prepare in advance. After all, with today's level of civilization will require at least 30 years to prepare for a meeting of potential killers.
The next challenge for the scientific community — to find smaller objects that are not able to destroy the biosphere, but can cause significant damage in a collision. To do this, scientists need a satellite orbiting around the sun directly inside the Earth's orbit — he can see about 90% of all asteroids with a diameter of 100 meters in 10 years. For its construction would require $ 300 million — and five years.