Earth is always at risk of a collision with a near-Earth object. NASA is constantly monitoring countless asteroids flying around in space, some of which are traveling in near-Earth orbits -- objects that could hit Earth. The chances are small, but the danger is there. The biggest of these objects could do severe damage, possibly wiping out huge parts of Earth's environment.
NASA has been following 99942 Apophis, for instance -- one huge near-Earth object (NEO) that, until recently, had a 2.7 percent chance of hitting Earth in 2029 [source: NASA]. NASA's research has shown that the 2029 approach will not be a hit, but that the movement into Earth's gravitational pull could alter the path of the asteroid enough to make it harder to predict the chances of a hit in 2036. Currently, those chances are considered to be 1 in 6,250 [source: NASA].
What to do? NASA is not just tracking these asteroids; it's also researching ways to avoid a hit. NASA scientists have looked into such methods as a gravity-tractor method of deflecting a collision. In that scenario, a spacecraft would either land on or orbit the near-Earth object, essentially pulling it out of a collision course by altering the gravitational pull.
If it comes to that, near-Earth object research will do more to save the environment than all the alternative-energy research, education and pollution studies combined. NASA could literally save the world.
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