@washingtonpost: Europa, one of the four large moons of Jupiter first seen by Galileo 414 years ago, may have a deep, salty, global ocean hidden beneath a thick crust of ice. Where there is water, there might be life. In an ambitious $5 billion mission decades in the making, NASA is poised to send a jumbo robotic probe called the Europa Clipper to see if the icy moon has the key characteristics of a habitable world.