One of the most profound breakthroughs in planetary science in the past two decades has been the discovery of liquid methane lakes on the surface of Saturn's largest moon Titan, and liquid oceans under the icy surfaces of many of the giant gas planets' other moons. Some of these space "waters" may actually harbor life, space experts say. An idea being explored is developing submarines to send through space to the moons. Over the next two years, NASA is devoting half a million dollars to researching the prospect of sending such a vehicle to Titan. Other studies target Jupiter's Europa and Ganymede, and Saturn's Enceladus. Are such missions actually within our technological reach? The answer to that question is maybe; it just depends on when these deep-space missions could be staged. Machine autonomy and machine vision technologies are improving all the time. The big challenges would be getting the space submarines to their destinations and communicating with them effectively.