How Europe Is Going to Land on a Comet

In November 2014, after traveling 10 years and hundreds of millions of miles, a European spacecraft will touch down on a two-and-a-half-mile-wide ball of ice and dust as it hurtles through space towards the sun. And if all goes according to plan, this unprecedented feat could finally give us what we need to understand the origins of life on Earth. It's just the "according to plan" that's the tricky part.