Asteroid Chasers   With a pair of binoculars you can see the Moon is carpeted with impact pockmarks. If you think about it, Earth has been hit more often than our heavenly neighbor, but the craters are hidden by water and vegetation, or healed by geologic movement. I've also read how unlikely NASA's "rock hunters" would miss identifying a big asteroid before it collided with our home planet and changed life as we know it.

 

What about a small one, bigger than a football field, which could level San Francisco Bay or cause a huge tsunami? Last March a 330-foot giant (2013 ET) missed Earth by 240,000 miles. The scary part is it wasn't discovered until 6 days before the event. Scientists will have the ability to track these smaller, but potentially destructive near-Earth objects when deep space telescope Sentinel is launched in 2018.

 If we detect the asteroid soon enough, a nuclear blast won't be necessary to divert its path from a hit to a miss. According to Scott Hubbard, a former NASA director, "We just need to alter its velocity by about the speed of an ant walking" to avoid disaster.