Jupiter’s moon Europa is one of the most intriguing bodies in the solar system. Its icy crust appears to cover a global ocean that could be many miles deep. Heat from deep within Europa could produce fountains of mineral-rich hot water at the bottom of the ocean. That combination could make Europa’s ocean a comfortable home for life. A couple of months ago, NASA asked scientists and engineers to suggest missions to explore this fascinating moon. It’s the first step toward what could eventually be an orbiter or lander. NASA frequently asks for proposals to explore the worlds of the solar system and beyond. Most of those proposals never make it off the ground, but a few eventually get funded and sent off into space. Even then, however, it generally takes years to develop an idea, build a craft, and send it on its way. In addition to the mission to Europa, NASA is also looking for proposals for ways to catch an asteroid and change its orbit. A robotic craft would push the asteroid into a
