NASA's Deep Space Atomic Clock is the Most Precise Clock in Space Launched on a satellite in June 2019, NASA's Deep Space Atomic Clock is the most precise clock to ever fly to space. The DSAC as it is abbreviated is at least 10 times more accurate than standard clocks to fly in space, like those on GPS satellites, which means it might be reliable for future space navigation systems. Current spacecraft and probes use signals from antennas earth to navigate the solar system, bouncing these signals back to get readings from clocks on earth to calculate position. These signals require very large, precise clocks and often it can take hours to pinpoint a spacecraft's position. Moving away from this method of navigation and using a clock on the spacecraft itself, the spacecraft would still need signals from earth to pinpoint its location, but wouldn't need to bounce them back. The DSAC gets its stability from electrically charged atoms, or ions, held within electric fields. The electric fields protect the ions, keeping the charges correct and precise so the clock can keep time properly. How stable is the DSAC? Researchers compared it with the U.S. Naval Observatory's hydrogen master clock on the ground and found it drifted about 26 picoseconds over a day. These trillionths of a second drift are comparable to clocks currently used in ground-based deep-space navigation.