One of Jupiter’s 95 known moons, Europa is almost the size of our own moon. It's encased in an ice sheet estimated to be 10 miles to 15 miles or more (15 kilometers to 24 kilometers) thick.

"It's like a game of billiards around the solar system, flying by a couple of planets at just the right angle and timing to build up the energy we need to get to Jupiter and Europa." Today (March ...