These seafaring robots will search for life across the solar system

We recognize Earth as the blue planet, but it's not the only ocean world in our neighborhood. Oceans may be concealed beneath thick crusts of ice on moons orbiting Jupiter, Saturn, and Neptune, and on the dwarf planets Pluto and Eris. Saturn's moon Titan even boasts liquid seas right on its surface, although they are full of methane rather than water. If anywhere in our solar system holds signs of life, it is likely to be these frigid worlds. Scientists are determined to explore the distant seas of Titan and Jupiter's moon Europa, and are designing ice-gripping rovers and submarines to take the plunge into their mysterious depths.