When people think of space technologies, many think of high-tech solar panels, complex and powerful propulsion systems or sophisticated, electronic guidance systems. Another critical piece of spaceflight technology, however, is an ultra stable, highly accurate device for timing — essential to NASA’s success on deep-space exploration missions. NASA is preparing to fly a Deep Space Atomic Clock, or DSAC, demonstration that will revolutionize the way we conduct deep-space navigation by enabling a spacecraft to calculate its own timing and navigation data in real time.