Stone Aerospace

The autonomous underwater robot known as DepthX has completed its exploration of one of the worlds deepest sinkholes, Mexicos Sistema Zacatón. Diving almost 1,100 feet into this massive, water-filled network of caves, DepthX penetrated far deeper than human divers have ever reached. It brought back samples of water and slime coating the cave walls.

If the asteroid Apophis were to collide with Earth 30 years from now, it would strike with the force of 57,000 Hiroshima bombs. The aircraft-carrier-size rock could wipe out a city the size of Los Angeles and cause a 30-foot tsunami to smack into southern California. There's only a 1 in 5,500 chance of impact, but it's a chance that NASA is not willing to take.

So in late October, the space agency outlined a three-phase plan to observe, track, and deflect the rogue rock over the next two decades.