Traveling the solar system could one day be as easy as taking a bus to work. Scientists envision self-driving spaceships ferrying astronauts through deep space, and GPS-like systems guiding visitors across the terrains of other planets and moons. But for those futuristic navigation schemes, spacecraft and satellites would need to be equipped with clocks that keep time with extreme precision — more precise than any timepiece ever sent to space.
A prototype of that clock is scheduled to launch on June 24 for a test flight.