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Wednesday, June 30, 2021

Six DeSales Student-Athletes Named Academic All-MAC - DSU Bulldogs

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Annville, PA (June 30, 2021) - Six DeSales University student-athletes were honored on Tuesday afternoon being named to the Academic All-MAC Team in their respective sports as announced by the conference office and as voted on by the Sports Information Directors in the MAC Freedom and MAC Commonwealth.

The Academic All-MAC teams recognize the top student-athletes both in the classroom and in athletic competition during the 2021 spring semester.  The team consists of 10 student-athletes from both the MAC Freedom and MAC Commonwealth teams voted on and selected by the Sports Information Directors of the MAC schools highlighting each student-athletes academic and athletic credentials.  To be eligible you must have a 3.2 GPA for the 2020-21 academic year.

The six student-athletes earning the honor this season were: freshman Elijah Eberly (Men's Basketball); juniors Rylie Rittenhouse and Averi Jordan (Women's Basketball); senior Vince Maria (Men's Lacrosse); junior Annie Rakos (Women's Tennis); senior Matthew Kraus (Men's Outdoor Track & Field).

Eberly, an accounting major, enjoyed a tremendous freshman season with the Bulldogs ranking second on the team in both scoring (10.0 PPG) and rebounding (5.7 RPG).  He shot a team-high 69.6 percent from the field and was second on the team with 13 blocked shots.

Rittenhouse, a nursing major, earns the honor for the first time in her career.  She was also named to the All-MAC Freedom First-Team and to the D3hoops.com All-Region Second-Team.  She finished the year averaging 10.9 points per game and led the MAC Freedom shooting 52.8 percent from the field.

Jordan, a nursing major, earns Academic All-MAC honors for the second straight season.  She was named to the All-MAC Freedom First-Team, MAC Freedom Player of the Year, D3hoops.com Atlantic/Mid-Atlantic Region Co-Player of the Year and First-Team, WBCA All-Region First-Team and WBCA HM All-American, D3hoops.com Third-Team All-American, and CoSIDA Academic All-District First-Team and Third Team All-American.  Jordan led the Bulldogs in scoring (15.9 PPG) and pulled down 5.0 rebounds per game.  She shot a career-high 51.9 percent from the field and 53.8 percent from three-point land.

Maria, a biology major, earns Academic All-MAC honors for the second time in his career.  He added this to also earning All-MAC Freedom First-Team honors and being named a USILA Honorable-Mention All-American.  Maria finished the year ranked third in the MAC Freedom with 2.45 CT's per game and totaled 27 caused turnovers and 43 ground balls as a defender.

Rakos, a medical studies major, earns Academic All-MAC honors for the first time in her career.  She was named to the All-MAC Freedom First-Team this season as well finishing the year with a 9-2 overall record, including a 6-2 record at the #1 singles flight.

Kraus, a biology major, earns Academic All-MAC honors for the fifth time in his career.  He won the Elite 90 award this season at the NCAA Division III Outdoor National Championships qualifying and finishing 11th in the 800-meters at the National Championships.  Kraus was also named USTFCCCA All-Region in the 800-meters and took home second place in the 800-meters at the MAC Outdoor Championships.

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eMobility Experience at CES 2022 Announced Test Track and Demo of Electric Bicycles and Electric Scooters Event Programming Produced by Electric Bike Events LLC - PRNewswire

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BETHESDA, Md. and LAS VEGAS, June 30, 2021 /PRNewswire/ -- Electric Bike Events LLC, a wholly-owned business unit of international trade show organizer E.J. Krause & Associates (EJK), announced today the formation of the eMobility Experience at CES 2022, taking place January 5-8 at the Las Vegas Convention Center (LVCC). The test track will include over 50 companies with bike and scooter brands, accessories and part suppliers.

"Electric bike sales continue to surge in the bike market. E-bikes and e-scooters are some of the hottest mobility products on the market both in the United States and internationally. Bringing a test track and demo area to CES, the most influential tech event in the world, reflects the importance of this growing category," said Ned Krause, CEO of E.J. Krause & Associates. "Our team has been behind the 22 ebike test track programs running across the US since 2016, including the experiential tracks at Interbike."

"The transportation industry has evolved rapidly to cleaner, electric powered vehicles and the world's leading brands choose to showcase this tech at CES," said Karen Chupka, EVP, CES, CTA. "We are excited for CES attendees to see and experience the latest innovations in electric bikes and electric scooters at the eMobility Experience at CES 2022."

The 65,000 square foot test track will include hills and ramps to test the motors, handling and acceleration features of the vehicles. Once an attendee completes their test of one vehicle, they can simply return it and pick up another. Attendees will also have access to a loaner helmet to use while testing (COVID protocols in effect). The test track will be open during all active show hours of CES, January 5 through 8, 2022. You must be a registered CES attendee to experience the test drive.

"There has been a strong need for a major national bike tradeshow to keep up with industry expansion, particularly a national forum for showcasing and testing bicycles, and ebikes. This program brings the ebike brands to an international stage with attendees, retailers, media and supplier partners already all in attendance. eBikes and escooters are all technology-centric and fit the profile of CES participants well. The program and exhibit format simply makes finding and evaluating the products significantly easier," said Bill Sell, eMobility Experience program manager.

The eMobility Experience will be part of the transportation and smart cities categories at CES. The transportation and vehicle tech category is on track for record growth at CES 2022. The transportation story is growing and expanding at CES, and many companies are focused on sharing electrification and self-driving technologies. Electric bicycles and electric scooters also fit into the smart cities story CES, as they are transforming urban mobility and sustainability.

For additional information on the eMobility Experience please visit: electricbikeevents.com 

SOURCE E.J. Krause & Associates, Inc.

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Demonstration of a trapped-ion atomic clock in space - Nature.com

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Abstract

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 exploration1 and global navigation satellite systems2, and are useful tools with which to address questions in fundamental physics3,4,5,6. Such satellite systems use precise measurement of signal propagation times determined by atomic clocks, together with propagation speed, to calculate position. 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 operation7. Methods of electromagnetically trapping and cooling ions have revolutionized atomic clock performance8,9,10,11,12,13. 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 programmes13, but transporting this new technology into space has remained challenging. Here we show the results from a trapped-ion atomic clock operating in space. On the ground, NASA’s Deep Space Atomic Clock demonstrated a short-term fractional frequency stability of 1.5 × 10−13/τ1/2 (where τ is the averaging time)14. 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. Each of these exceeds current space clock performance by up to an order of magnitude15,16,17. 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. 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 possible18.

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Fig. 1: The Deep Space Atomic Clock launch.
Fig. 2: Clock vacuum chamber and traps.
Fig. 3: Clock frequency offsets in space.
Fig. 4: Clock stability in space.

Data availability

Full data for Fig. 4 and Extended Data Fig. 3 are available from the corresponding author on reasonable request.

References

  1. 1.

    Thornton, C. L. & Border, J. S. Radiometric Tracking Techniques for Deep-Space Navigation (Wiley-Interscience, 2003).

  2. 2.

    Mallette, L. A., White, J. & Rochat, P. Space qualified frequency sources (clocks) for current and future GNSS applications. IEEE/ION Position Locat. Navig. Symp. (Online), https://doi.org/10.1109/PLANS.2010.5507225 (2010).

    Article  Google Scholar 

  3. 3.

    Prestage, J. D., Tjoelker, R. L. & Maleki, L. Atomic clocks and variations of the fine structure constant. Phys. Rev. Lett. 74, 3511 (1995).

    CAS  Article  Google Scholar 

  4. 4.

    Safronova, M. S. The search for variation of fundamental constants with clocks. Ann. Phys. 531, 1800364 (2019).

    Article  Google Scholar 

  5. 5.

    McGrew, D. et al. Atomic clock performance enabling geodesy below the centimetre level. Nature 564, 87 (2018).

    CAS  Article  Google Scholar 

  6. 6.

    Hees, A., Guéna, J., Abgrall, M., Bize, S. & Wolf, P. Searching for an oscillating massive scalar field as a dark matter candidate using atomic hyperfine frequency comparisons. Phys. Rev. Lett. 117, 061301 (2016).

    CAS  Article  Google Scholar 

  7. 7.

    Vessot, R. F. C. et al. Test of relativistic gravitation with a space-borne hydrogen maser. Phys. Rev. Lett. 45, 2081 (1980).

    Article  Google Scholar 

  8. 8.

    Prestage, J. D., Dick, G. J. & Maleki, L. Linear ion trap based atomic frequency standard. IEEE Trans. Instrum. Meas. 40, 132 (1991).

    CAS  Article  Google Scholar 

  9. 9.

    Cutler, L. S., Giffard, R. P. & McGuire, M. D. A trapped mercury 199 ion frequency standard. In Proc. 13th Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting, 563–577 (Institute of Navigation, 1981).

  10. 10.

    Tjoelker, R. L. et al. A mercury ion frequency standard engineering prototype for the NASA deep space network. In Proc. 50th IEEE International Frequency Control Symposium, 1073–1081 (IEEE, 1996).

  11. 11.

    Burt, E. A., Diener, W. A. & Tjoelker, R. L. A compensated multi-pole linear ion trap mercury frequency standard for ultra-stable timekeeping. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 55, 2586 (2008).

    Article  Google Scholar 

  12. 12.

    Hinkley, N. et al. An atomic clock with 10−18 instability. Science 341, 1215 (2013).

    CAS  Article  Google Scholar 

  13. 13.

    Brewer, S. M. et al. 27Al+ quantum-logic clock with a systematic uncertainty below 10−18. Phys. Rev. Lett. 123, 033201 (2019).

    CAS  Article  Google Scholar 

  14. 14.

    Tjoelker, R. L. et al. Deep Space Atomic Clock (DSAC) for a NASA Technology Demonstration Mission. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 63, 1034–1043 (2016).

    Article  Google Scholar 

  15. 15.

    Lutwak, R., Emmons, D., Garvey, R. M. & Vlitas, P. Optically pumped cesium-beam frequency standard for GPS-III. In Proc. 33rd Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting, 19–30 (Institute of Navigation, 2001).

  16. 16.

    Riley, W. J. Rubidium atomic frequency standards for GPS block IIR. In Proc. 22nd Annual Precise Time and Time Interval (PTTI), 221–230 (Institute of Navigation, 1990).

  17. 17.

    Droz, F. et al. Space passive hydrogen maser—performances and lifetime data. In Proc. 2009 IEEE International Frequency Control Symposium Joint with the 22nd European Frequency and Time Forum, 393–398 (IEEE, 2009).

  18. 18.

    Seubert, J., Ely, T. & Stuart, J. Results of the deep space atomic clock deep space navigation analog experiment. In Proc. AAS/AIAA Astrodynamics Specialist Conference (American Astronomical Society, in the press).

  19. 19.

    Codik, A. Autonomous navigation of GPS satellites: a challenge for the future. J. Inst. Navig. 32, 221–232 (1985).

    Article  Google Scholar 

  20. 20.

    Dehmelt, H. G. Monoion oscillator as potential ultimate laser frequency standard. IEEE Trans. Instrum. Meas. IM-31, 83–87 (1982).

    CAS  Article  Google Scholar 

  21. 21.

    Liu, L. et al. In-orbit operation of an atomic clock based on laser-cooled 87Rb atoms. Nat. Commun. 9, 2760 (2018).

    Article  Google Scholar 

  22. 22.

    Tjoelker, R. L. et al. Mercury atomic frequency standards for space-based navigation and timekeeping. In Proc. 43rd annual Precise Time and Time Interval (PTTI) Systems and Applications Meeting, 209–304 (Institute of Navigation, 2011).

  23. 23.

    Prestage, J.D., Chung, S., Le, T., Lim, L., and Maleki, L. Liter sized ion clock with 10−15 stability. In Proc. Joint IEEE IFCS and PTTI, 472–476 (IEEE, 2005).

  24. 24.

    Prestage, J. D. & Weaver, G. L. Atomic clocks and oscillators for deep-space navigation and radio science. Proc. IEEE 95, 2235–2247 (2007).

    Article  Google Scholar 

  25. 25.

    Ely, T. A., Seubert, J. & Bell, J. in Space Operations: Innovations, Inventions, and Discoveries, 105–138 (American Institute of Aeronautics and Astronautics, Inc., 2015).

  26. 26.

    Ely, T. A., Burt, E. A., Prestage, J. D., Seubert, J. M. & Tjoelker, R. L. Using the Deep Space Atomic Clock for navigation and science. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 65, 950–961 (2018).

    Article  Google Scholar 

  27. 27.

    Prestage, J. D., Dick, G. J. & Maleki, L. New ion trap for frequency standard applications. J. Appl. Phys. 66, 1013 (1989).

    Article  Google Scholar 

  28. 28.

    Prestage, J. D., Tjoelker, R. L. & Maleki, L. Higher pole linear traps for atomic clock applications. In Proc. 1999 Joint European Frequency and Time Forum and IEEE International Frequency Control Symposium, 121–124 (IEEE< 1999).

  29. 29.

    Dicke, R. H. The effect of collisions upon the Doppler width of spectral lines. Phys. Rev. 89, 472 (1953).

    CAS  Article  Google Scholar 

  30. 30.

    Enzer, D., Diener, W., Murphy, D., Rao, S. & Tjoelker, R. L. Drifts and environmental disturbances in atomic clock subsystem: quantifying local oscillator, control loop, & ion resonance interactions. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 64, 623–633 (2017).

    Article  Google Scholar 

  31. 31.

    Ely, T. A., Murphy, D., Seubert, J., Bell, J. & Kuang, D. Expected performance of the Deep Space Atomic Clock Mission. In Proc. AAS/AIAA Space Flight Mechanics Meeting, 807–826 (American Astronomical Society, 2014).

  32. 32.

    Howe, D. A., Allan, D. W. & Barnes, J. A. Properties of signal sources and measurement methods. In Proc. 35th Annual IEEE Symposium on Frequency Control, 1–47 (IEEE, 1981).

  33. 33.

    Dick, G. J. Local oscillator induced instabilities in trapped ion frequency standards. In Proc. 19th Precise Time and Time Interval Symposium, 133–147 (Institute of Navigation, 1987).

  34. 34.

    Larson, K. M. & Levine, J. Time transfer using the phase of the GPS carrier. In Proc. 1998 IEEE International Frequency Control Symposium, 292–297 (IEEE, 1998).

  35. 35.

    Bertiger, W. et al. Single receiver phase ambiguity resolution with GPS data. J. Geod. 84, 327–337 (2010).

    Article  Google Scholar 

  36. 36.

    Petit, G. Sub-10−16 accuracy GNSS frequency transfer with IPPP. GPS Solut. 25, 22 (2021).

    Article  Google Scholar 

  37. 37.

    Larson, K. M., Ashby, N., Hackman, C. & Bertiger, W. An assessment of relativistic effects for low earth orbiters: the GRACE satellites. Metrologia 44, 484 (2007).

    Article  Google Scholar 

  38. 38.

    Prestage, J. D., Tjoelker, R. L., Dick, G. J. & Maleki, L. Doppler sideband spectra for ions in a linear trap. In Proc. IEEE International Frequency Control Symposium, 148–154 (IEEE, 1993).

  39. 39.

    Tjoelker, R. L., Prestage, J. D., Dick, G. J. & Maleki, L. Long term stability of Hg+ trapped ion frequency standards. In Proc. 1993 IEEE International Frequency Control Symposium, 132–138 (IEEE, 1993).

  40. 40.

    Burt, E. A. & Tjoelker, R. L. Prospects for ultra-stable timekeeping with sealed vacuum operation in multi-pole linear ion trap standards. In Proc. 39th Annual Precise Time and Time Interval Systems and Applications Meeting, 309–316 (Institute of Navigation, 2008).

  41. 41.

    Chung, S. K., Prestage, J. D. & Tjoelker, R. L. Buffer gas experiments in mercury (Hg+) ion clock. In Proc. IEEE International Frequency Control Symposium, 130–133 (IEEE, 2004).

  42. 42.

    Yi, L., Taghavi-Larigani, S., Burt, E. A. & Tjoelker, R. L. Progress towards a dual-isotope trapped mercury ion atomic clock: further studies of background gas collision shifts. In Proc. 2012 IEEE International Frequency Control Symposium, 1–5 (IEEE, 2012).

  43. 43.

    Shen, G. L. The pumping of methane by an ionization assisted Zr/Al getter pump. J. Vac. Sci. Technol. A 5, 2580 (1987).

    CAS  Article  Google Scholar 

  44. 44.

    Konradi, A., Badhwar, G. D. & Braby, L. A. Recent space shuttle observations of the South Atlantic Anomaly and the radiation belt models. Adv. Space Res. 14, 911–921 (1994).

    CAS  Article  Google Scholar 

  45. 45.

    Ginet, G. P., Madden, D., Dichter, B. K. & Brautigam, D. H. Energetic Proton Maps for the South Atlantic Anomaly. In Proc. 2007 IEEE Radiation Effects Data Workshop, 1–8 (IEEE, 2007).

  46. 46.

    Jerde, R. L., Peterson, L. E. & Stein, W. Effects of high energy radiations on noise pulses from photomultiplier tubes. Rev. Sci. Instrum. 38, 1387 (1967).

    CAS  Article  Google Scholar 

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Acknowledgements

This work is jointly funded by NASA’s Space Technology Mission Directorate (STMD) office and the office of Space Communications and Navigation (SCaN). The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). Copyright 2020, California Institute of Technology. Government sponsorship acknowledged.

Author information

Author notes

  1. These authors contributed equally: Eric A. Burt, John D. Prestage, Robert L. Tjoelker

Affiliations

  1. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA

    E. A. Burt, J. D. Prestage, R. L. Tjoelker, D. G. Enzer, D. Kuang, D. W. Murphy, D. E. Robison, J. M. Seubert, R. T. Wang & T. A. Ely

Authors
  1. E. A. Burt
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Contributions

E.A.B., J.D.P. and R.L.T. contributed equally. E.A.B. led DSAC clock preparation and optimization, determined operation modes and parameters, characterized the clock and payload before launch and in space, and led manuscript preparation activity. J.D.P. is the DSAC clock co-investigator, led the vacuum tube, ion trap, optics and magnetic design, and consulted on all other aspects of clock preparation, characterization and data analysis. R.L.T. is the DSAC clock co-investigator, consulted on all aspects of clock and payload design, preparation, characterization and data analysis, and led efforts to resolve several technical challenges with the instrument. D.G.E. led the development of telemetry processing and analysis tools, characterized local oscillator and system performance, and performed USO and control loop modelling. D.K. contributed GPS data processing, modelling and analysis. D.W.M. led the GPS data processing, modelling and analysis, including relativistic calculations and orbital parameter analysis, and wrote telemetry processing and display software. D.E.R. led controller algorithm implementation and data acquisition, and coordinated clock commanding through the spacecraft provider. J.M.S. was the DSAC deputy principal investigator and led technical and programmatic planning and performed the new one-way navigation experiments enabled by DSAC. T.A.E. is the DSAC principal investigator, led technical and programmatic planning and performed the new one-way navigation experiments enabled by DSAC, and with D.W.M. devised new methods to perform GPS receiver thermal calibrations. R.T.W led USO characterizations, instrument integration into the payload and payload integration into the spacecraft. All authors read, edited and approved the final manuscript.

Corresponding author

Correspondence to E. A. Burt.

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Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature thanks Pascale Defraigne, Ekkehard Peik and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 System-level block diagram of the DSAC payload.

The GPS receiver (Rcv.) is not shown.

Extended Data Fig. 2 Level diagram for 199Hg(II).

The S1/2, F = 1 to P1/2, F = 1 optical electric dipole transition used for state preparation and readout is shown in purple (note that the source of this light is broad enough to not resolve Zeeman sublevels, so the line is meant to indicate any transition between the S1/2 F = 1 and P1/2 F = 1 manifolds that is consistent with selection rules). Also shown are the S1/2, F = 0, mF = 0 to S1/2, F = 1, mF = 0 magnetic-field-insensitive 40.5-GHz hyperfine clock transition (thick black arrow), and the ΔmF = ±1 field-sensitive Zeeman lines at ±140 kHz (thin black arrows).

Extended Data Fig. 3 Measured Allan deviation.

Allan deviation without any corrections (red), with relativity corrections but no temperature corrections (green), and with both relativity and temperature corrections (black). Simulated expected clock performance with clock parameters during the run with environmental perturbations (solid blue) and without (dashed blue) is shown for comparison. All traces except the blue are overlapping Allan deviation. For reference, the orbital period of about T = 6,000 s will result in expected peaks in the Allan deviation at 0.37T ≈ 2,200 s (ref. 30).

Extended Data Fig. 4 Variations in the Earth’s magnetic field observed on the DSAC spacecraft as a function of time.

The orbital period is approximately 6,000 s at an altitude of 720 km.  The component of the fieldin the weakest shielding direction is plotted.  Shielding in the other two directions is over an order of magnitude higher so that the impact of variations on the clock is dominated by the component shown.

Extended Data Fig. 5 Impact of magnetic field variations on the clock.

The Allan deviation of the frequency shift associated with measured magnetic field variations on board the DSAC spacecraft is shown (red) assuming a worst-case sensitivity of 7 × 10−16 μT−1. Reference lines are also shown for expected multipole trap (dashed blue) and load trap (dashed black) operation noise floors (without LO noise aliasing effects for the multipole trap line). Error bars represent 68% confidence intervals.

Extended Data Fig. 6 Fractional frequency versus signal size in the load trap.

Signal size is the number of PMT counts measured at the line centre minus the counts at a detuning of one linewidth corresponding to the first minimum in a Rabi line trace. The slope gives an estimate of the number-dependent second-order Doppler shift while operating in the load trap. As a point of reference, the corresponding shift in the multipole trap would be 10–20 times smaller.

Extended Data Fig. 7 Residuals from a fit to frequency versus signal size.

Residuals are now plotted against temperature in the load trap. A linear fit gives a total temperature sensitivity of −2.3(1.1) × 10−15 °C−1.

Extended Data Fig. 8 Temperature data.

Temperature data shown for the 52-day dataset described in the main text. a, Long-term temperature variation in the load trap over 52 days correlated with changes in Sun beta angle. b, A 5-day subset showing 24-h temperature variations. c, A 1-day subset showing orbital temperature variation.

Extended Data Fig. 9 Trace-gas evolution.

Frequency data with the temperature effect removed (black dots) and fitted to a straight line (blue line), so as to place a limit of 4.6 × 10−16 per day on frequency shifts due to trace-gas evolution in the clock vacuum chamber.

Extended Data Fig. 10 Passage through the SAA.

Total PMT counts in 8.1-s portions of each clock cycle as a function of time, showing excess counts due to passage through the SAA. Each passage is approximately 20 min, as shown for the expanded view (inset). The varying peak amplitude is due to spacecraft orbital precession, which varies the trajectory of the spacecraft in and out of the SAA on a daily timescale.

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Burt, E.A., Prestage, J.D., Tjoelker, R.L. et al. Demonstration of a trapped-ion atomic clock in space. Nature 595, 43–47 (2021). https://ift.tt/2SDEIO1

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