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Optically pumped cesium-beam frequency standard for GPS-III.
![atomic clock atomic clock](https://images-na.ssl-images-amazon.com/images/I/813yQgBypSL._AC_SL1500_.jpg)
Deep Space Atomic Clock (DSAC) for a NASA Technology Demonstration Mission. 27Al + quantum-logic clock with a systematic uncertainty below 10 −18. A compensated multi-pole linear ion trap mercury frequency standard for ultra-stable timekeeping. 50th IEEE International Frequency Control Symposium, 1073–1081 (IEEE, 1996).īurt, E. A mercury ion frequency standard engineering prototype for the NASA deep space network. 13th Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting, 563–577 (Institute of Navigation, 1981). A trapped mercury 199 ion frequency standard. Linear ion trap based atomic frequency standard. Test of relativistic gravitation with a space-borne hydrogen maser. Searching for an oscillating massive scalar field as a dark matter candidate using atomic hyperfine frequency comparisons. Hees, A., Guéna, J., Abgrall, M., Bize, S. Atomic clock performance enabling geodesy below the centimetre level. The search for variation of fundamental constants with clocks. Atomic clocks and variations of the fine structure constant. Space qualified frequency sources (clocks) for current and future GNSS applications. Radiometric Tracking Techniques for Deep-Space Navigation (Wiley-Interscience, 2003).
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This level of space clock performance will enable one-way navigation in which signal delay times are measured in situ, making near-real-time navigation of deep space probes possible 18. The Deep Space Atomic Clock is particularly amenable to the space environment because of its low sensitivity to variations in radiation, temperature and magnetic fields. Each of these exceeds current space clock performance by up to an order of magnitude 15, 16, 17. Launched in 2019, the clock has operated for more than 12 months in space and demonstrated there a long-term stability of 3 × 10 −15 at 23 days (no drift removal), and an estimated drift of 3.0(0.7) × 10 −16 per day. On the ground, NASA’s Deep Space Atomic Clock demonstrated a short-term fractional frequency stability of 1.5 × 10 −13/ τ 1/2 (where τ is the averaging time) 14. Here we show the results from a trapped-ion atomic clock operating in space.
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Terrestrial trapped-ion clocks operating in the optical domain have achieved orders-of-magnitude improvements in performance over their predecessors and have become a key component in national metrology laboratory research programmes 13, but transporting this new technology into space has remained challenging. Methods of electromagnetically trapping and cooling ions have revolutionized atomic clock performance 8, 9, 10, 11, 12, 13. Although space atomic clocks with low instability are an enabling technology for global navigation, they have not yet been applied to deep space navigation and have seen only limited application to space-based fundamental physics, owing to performance constraints imposed by the rigours of space operation 7. Such satellite systems use precise measurement of signal propagation times determined by atomic clocks, together with propagation speed, to calculate position. Atomic clocks, which lock the frequency of an oscillator to the extremely stable quantized energy levels of atoms, are essential for navigation applications such as deep space exploration 1 and global navigation satellite systems 2, and are useful tools with which to address questions in fundamental physics 3, 4, 5, 6.