Currently, navigation in space actually requires all of the decisions to be made on Earth. This kind of precision timing will be needed for future deep space missions. He anticipates that during the next phase of the mission, the JPL team will achieve even lower frequency variations, further improving the clock’s performance. “These on-orbit frequency stability results are very encouraging for the technology,” even though the clock did not operate in its optimal settings while in space, says Camparo, who holds a doctorate in chemical physics and was not involved in the study. James Camparo of the Aerospace Corporation thinks the drift of their clock is exceptionally low. If it’s at the wrong frequency, nothing happens.” “If it’s at the right frequency, then you get a lot of atoms jumping around. “One way to envision it is that the atomic portion is just a steering wheel on the oscillator,” says Burt. ![]() That means scientists can monitor the stability of their clocks by observing the activity of the atoms it is paired with. To jump into higher orbits, the electrons must be given energy of just the right frequency. (This clock uses mercury, but others have used cesium, rubidium, or strontium.) Atoms are made up of electrons circling a nucleus, and these electrons can exist only in specific, discrete orbits, based on how much energy they have. So, Burt says, atomic clocks pair an oscillator with a collection of atoms to help keep that frequency stable. The frequency of that vibration, or how many oscillations occur in a second, is how clocks keep time, or tick.īut oscillators are fickle-the stability of their frequency degrades over time, a phenomenon known as drift. “It could be as simple as a pendulum arm swinging, or it could be a quartz crystal like you have in your watch or iPhone,” Burt says. “And our clock can play a role in that.”Ītomic clocks, like every other kind, start with an oscillator: something that vibrates. “A robust onboard navigation system is going to be a fundamental component to human exploration beyond Earth,” says Ely, the project’s principal investigator. ![]() ![]() It’s the most precise clock to ever operate in space, and it’s paving the way for making real-time navigation of the cosmos a reality. Ely and Burt are two leaders of the Deep Space Atomic Clock project at NASA’s Jet Propulsion Laboratory, and in September-more than two years after the clock’s deployment into low Earth orbit-the clock’s satellite was powered off, marking the end of its first mission. “I watched it from three miles away, thinking: How is our little clock going to ever survive?”īut it did. Despite all of the shake tests they had performed beforehand to ensure their delicate device could endure the journey into space, the violence of the launch left Burt in disbelief. “You feel it in your chest,” he recalls.Īlso at the site was Ely’s colleague Eric Burt, a physicist who is an expert on atomic clocks. He distinctly remembers a bright flash and a beating vibration that lasted long after the light went dim. It was 2:30 in the morning when astronautical engineer Todd Ely watched as a little atomic clock-the size of a four-slice toaster-was launched into space on a satellite attached to one of the most powerful rockets in the world.
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