The asteroid that came so close to Earth recently is the closest a stellar body has come to the Earth in a very long time. It was 17,000 miles away from the Earth at the closest approach and this resulted in some small rocks entering the atmosphere and either exploding in the atmosphere or hitting the ground and causing minor damage. The size of the asteroid was nothing compared to the Asteroid that wiped out the Dinosaurs 65 million years ago. It was a near miss this time but the rocks pulled along behind the asteroid became the shrapnel that pummeled our planet. But it was only a very small asteroid that endangered the planet. If the rock had hit the Earth the damage would have been severe if it had hit a populated area, but if it had struck in the middle of the Gobi desert or the Sahara then it would have expended its energy before the blast wave reached a populated area. There are larger rocks in the asteroid belt, but the massive gravitational pull of Jupiter sucks in most of the rocks that come past the Jovian gravity well. That is why we are so blessed in our solar system; we have a huge gas giant that has 8 times Earth`s gravity and vacuums up all the space junk that happens to come too close. So much worry and panic over such small meteorites that burned up in the atmosphere before they could do a great amount of damage. DA14 is a spectacle that we might not see again for a long time.
I remember seeing a meteorite burning up in the atmosphere as a young child, it was quite a large rock, but it did not result in a massive explosion like the Russian meteorites did. But seeing something like that with your own eyes is something else indeed. It goes to show that living in the cosmos that we inhabit is dangerous but the thick atmosphere of our planet burns up rocks before they can hit us. This asteroid was only 150 feet or 45 meters in diameter. Very small considering the size of some of the rocks orbiting in the asteroid belt. Sometimes they collide with each other and this can knock a large object into a collision course with Earth. Read more about asteroid DA14 on this educational page: http://www.nasa.gov/topics/solarsystem/features/asteroidflyby.html. Just goes to show how much of a near miss this was. But we are safe after all; the world did not end and no cities suffered serious damage in the impacts. Movies like Deep Impact show the results of a small comet impacting the Earth and the destruction to the cities that tsunami caused. Earth has suffered unimaginably massive impacts early in its lifespan due to the enormous amount of debris floating around in the young solar system. Thankfully this debris is gone now; only the asteroid belt and the Kuiper belt still holds the largest amounts of dangerous rocks. I wish that we could place an asteroid into Earth orbit in a safe altitude; then we could mine it and gain some useful material that would be very good for Earth.
We would get so much material that it would be worth the effort to send up rockets and bring back material. Constructing a new spaceship like a space shuttle to hold large amounts of material would be worth the expenditure to gain mineral wealth. Space is the future and we need to invest more into the conquest of our solar system before we are rendered extinct by a natural disaster or nuclear war. The classic Charlton Heston movie Planet of the Apes showed this graphically when the protagonist realizes that the planet he is on was the post nuclear-holocaust Earth all along and the people in charge had blown it all up. That is a very powerful scene indeed. If only they could have used a slingshot around the Sun and traveled back in time to stop the nuclear war. But they would not have had Spock or the warp drive needed to achieve time warp and rescue humanity. The Star Trek movie that involved the Cretacean probe and the rescue of the whales from the 20th century was the best in my opinion. The time travel trope was well done, I am assuming that they used FTL travel to go backwards in time. But this in reality is not possible as exceeding the speed of light is impossible. An object at 99.99999999999999999999999% of the speed of light would have 99.99999999999999999999999% of infinite mass and it would not be able to be accelerated to the speed of light. This is why we cannot travel to the stars in FTL spaceships.
You need to find a workaround to the limitations of space time. Enclosing the spacecraft in a bubble of space time and using space folding or warp drive would provide a method of reaching the stars. The Alcubierre drive is one possibility; or if we could fold space like the Guild Navigator in Dune. Piloting the Guild Heighliners travelling from one planet to another without moving. That is another way of reaching any point in the Universe. As long as you could calculate where the ship would materialize when you came out in the destination. That would require very complex mathematics.