ATOMIC CLOCK ENSEMBLE IN SPACE Mission status

Transcription

1 ATOMIC CLOCK ENSEMBLE IN SPACE Mission status Luigi Cacciapuoti on behalf of the ACES team 30/03/2017 Rencontres de Moriond Gravitation, La Thuile

2 ACES Luigi Cacciapuoti 30/03/2017 Slide 2

3 The Columbus module Luigi Cacciapuoti 30/03/2017 Slide 3

4 The ACES Payload o PHARAO (CNES): Atomic clock based on laser cooled Cs atoms o SHM (ESA): Active hydrogen maser o FCDP (ESA): Clocks comparison and distribution o MWL (ESA): T&F transfer link o GNSS receiver (ESA) o ELT (ESA): Optical link o Support subsystems (ESA) XPLC: External PL computer PDU: Power distribution unit, Mechanical, thermal subsystems CEPA: Columbus External PL Adapter (ESA-NASA) Volume: 1172x867x1246 mm 3 Mass: 227 kg Power: 450 W Luigi Cacciapuoti 30/03/2017 Slide 4

5 ACES Servo-loops SHM FCDP PHARAO 100 MHz 100 MHz FLL PLL Detsynch XPLC Luigi Cacciapuoti 30/03/2017 Slide 5

6 ACES Clocks and Links Performance PHARAO accuracy ~ MWL ground terminal ELT detector Luigi Cacciapuoti 30/03/2017 Slide 6

7 ACES Integration Activities Luigi Cacciapuoti 30/03/2017 Slide 7

8 ACES Pre-IST (Integrated System Tests) Luigi Cacciapuoti 30/03/2017 Slide 8

9 SHM: An Active H-maser for Space o SHM role in ACES ACES flywheel oscillator PHARAO characterization o Technical challenges Low mass, volume, and power consumption Full performances: o s o s Design solution Full size Al cavity Automatic Cavity Tuning System (ACT) Volume: 390x390x590 mm 3 Mass: 42 kg Luigi Cacciapuoti 30/03/2017 Slide 9

10 SHM EM Stability Luigi Cacciapuoti 30/03/2017 Slide 10

11 PHARAO FM Integration Luigi Cacciapuoti 30/03/2017 Slide 11

12 Flight Model of the PHARAO Lasers Source Luigi Cacciapuoti 30/03/2017 Slide 12

13 PHARAO FM Ramsey Fringes Contrast: 0.9 Linewidth: 5.6 Hz Luigi Cacciapuoti 30/03/2017 Slide 13

14 PHARAO FM Stability Autonomous Mode On ground: In space: / τ / τ Luigi Cacciapuoti 30/03/2017 Slide 14

15 ACES Backup Mode Detsynch 1/τ slope Luigi Cacciapuoti 30/03/2017 Slide 15

16 PHARAO FM Frequency Shift and Accuracy 2 nd order Zeeman effect ( ν=1372 Hz) Blackbody radiation (T= mk) Cold collisions (N= ) 1 st order Doppler effect Main frequency shifts ( ) ADS H-maser UTC (via GPS) Gravitational redshift (410 m) 47.3 Total 205 PHARAO ADS H-maser 1579 ADS H-maser UTC Total 205 PHARAO Accuracy CNES): o On ground: o In space: < Luigi Cacciapuoti 30/03/2017 Slide 16

17 MWL o o Two-way link: Removal of the troposphere time delay ( ns) Removal of 1st order Doppler effect Removal of instrumental delays and common mode effects Additional down-link in the S-band: Determination of the ionosphere TEC Correction of the ionosphere time delay ( ns in S-band, ps in Kuband) o o Phase PN code modulation: Removal of 2π phase ambiguity High chip rate (100 MChip/s) on the code: o o o Higher resolution Multipath suppression Carrier and code phase measurements (1 per second) Data link: 2 kbits/s on the S-band down-link to obtain clock comparison results in real time Up to 4 simultaneous space-to-ground clock comparisons Luigi Cacciapuoti 30/03/2017 Slide 17

18 MWL EM End-to-end Test MWL ground terminal MWL on-board electronics Luigi Cacciapuoti 30/03/2017 Slide 18

19 MWL EM Results 2-way carrier phase in static conditions 2-way carrier phase under signal dynamics Luigi Cacciapuoti 30/03/2017 Slide 19

20 ACES Network Luigi Cacciapuoti 30/03/2017 Slide 20

21 European Laser Timing (ELT) TM/TC Power ACES tt space ACES Time Scale (MWL) Detector package 500 grams 0.6 Watt tt stop tt start ττ g tt ττ s tt = tt start + tt stop tt 2 space + +ττ relativity + ττ atmosphere + ττ geometry CTU Prague Luigi Cacciapuoti 30/03/2017 Slide 21

22 ELT FM Performance SPAD FM stability Time tagging board EM stability Luigi Cacciapuoti 30/03/2017 Slide 22

23 ILRS Network of SLR Stations ACES submitted to ILRS as target: Wettzell, the ACES primary station already calibrated; Gratz and Herstmonceaux will follow; other stations can join provided they comply with ISS safety requirements. Luigi Cacciapuoti 30/03/2017 Slide 23

24 Fundamental Physics Tests ACES Mission Objectives ACES performances Scientific background and recent results Fundamental physics tests Measurement of the gravitational red shift Absolute measurement of the gravitational red-shift at an uncertainty level < after 300 s and < after 10 days of integration time. Space-to-ground clock comparison at the level, will yield a factor 70 improvement on previous measurements (GPA experiment). Search for time drifts of fundamental constants Time variations of the fine structure constant a at a precision level of α -1 da / dt < year -1 down to year -1 in case of a mission duration of 3 years Optical clocks progress will allow clock-toclock comparisons below the level. Crossed comparisons of clocks based on different atomic elements will impose strong constraints on the time drifts of a, m e /Λ QCD, and m u /Λ QCD. Search for violations of special relativity Search for anisotropies of the speed of light at the level δ c / c < ACES results will improve present limits on the RMS parameter a based on fast ions spectroscopy and GPS satellites by one and two orders of magnitudes respectively. Luigi Cacciapuoti 30/03/2017 Slide 24

25 Gravitational Redshift Test ddττ gg dddd ddττ ss dddd = 1 cc 2 UU tt, xx ss UU tt, xx gg + vv ss 2 tt 2 vv gg 2 tt 2 Frequency shifts First order Doppler effect Second order Doppler effect Gravitational red-shift Sagnac effect OO 1 cc 4 Luigi Cacciapuoti 30/03/2017 Slide 25

26 Relativistic Geodesy U 1 U 2 Relativistic geodesy: mapping of the Earth gravitational potential based on the precision measurement of the red-shift experienced by two clocks at two different locations o ACES will perform intercontinental comparisons of optical clocks at the level after 1 week of integration time, measuring the local height of the geoid at the 10 cm level. o The global coverage offered by ACES will complement the results of the CHAMP, GRACE, and GOCE missions. Luigi Cacciapuoti 30/03/2017 Slide 26

27 Fundamental Physics Tests ACES Mission Objectives ACES performances Scientific background and recent results Fundamental physics tests Measurement of the gravitational red shift Absolute measurement of the gravitational red-shift at an uncertainty level < after 300 s and < after 10 days of integration time. Space-to-ground clock comparison at the level, will yield a factor 35 improvement on previous measurements (GPA experiment). Search for time drifts of fundamental constants Time variations of the fine structure constant a at a precision level of α -1 dα / dt < year -1 down to year -1 in case of a mission duration of 3 years Optical clocks progress will allow clock-toclock comparisons below the level. Crossed comparisons of clocks based on different atomic elements will impose strong constraints on the time drifts of a, m e /Λ QCD, and m u /Λ QCD. Search for violations of special relativity Search for anisotropies of the speed of light at the level δ c / c < ACES results will improve present limits on the RMS parameter a based on fast ions spectroscopy and GPS satellites by one and two orders of magnitudes respectively. Luigi Cacciapuoti 30/03/2017 Slide 27

28 Fundamental Constants Frequency of hyperfine transitions: Frequency of electronic transitions: Ratios between atomic frequencies: Sensitivity to time variations of fundamental constants: Luigi Cacciapuoti 30/03/2017 Slide 28

29 Fundamental Constants Luigi Cacciapuoti 30/03/2017 Slide 29

30 Fundamental Physics Tests ACES Mission Objectives ACES performances Scientific background and recent results Fundamental physics tests Measurement of the gravitational red shift Absolute measurement of the gravitational red-shift at an uncertainty level < after 300 s and < after 10 days of integration time. Space-to-ground clock comparison at the level, will yield a factor 70 improvement on previous measurements (GPA experiment). Search for time drifts of fundamental constants Time variations of the fine structure constant a at a precision level of α -1 da / dt < year -1 down to year -1 in case of a mission duration of 3 years Optical clocks progress will allow clock-toclock comparisons below the level. Crossed comparisons of clocks based on different atomic elements will impose strong constraints on the time drifts of a, m e /Λ QCD, and m u /Λ QCD. Search for violations of special relativity Search for anisotropies of the speed of light at the level δ c / c < ACES results will improve present limits on the RMS parameter a based on fast ions spectroscopy and GPS satellites by one and two orders of magnitudes respectively. Luigi Cacciapuoti 30/03/2017 Slide 30

31 Special Relativity Tests Kinematic test theories (RMS framework): Preferred reference frame (CMB) in which light is assumed to propagate isotropically Dynamic test theories (SME framework): Lorentz transformations violating terms in the Hamiltonian of the system δc + 2 T c δc c cosθ ( T T ) ( T T ) + = 2 T ( 1 cosθ ) 1 T 2 1 T 2 3 = s 4 + l a Measurement principle: o Exchange of microwave signals between ACES clocks and ground clocks along the ISS orbit o Difference of measured reception and emission times provides the one-way travel time of the signal plus some unknown constant offset (desynchronization, path asymmetries, propagation delay ) o Difference of the up and down travel times sensitive to a non zero value of δc/c P. Wolf, PRA 51, 5016 (1995) Luigi Cacciapuoti 30/03/2017 Slide 31

32 Applications o o o o o o Clock comparisons over intercontinental distances: in less than 1 week Absolute time transfer and time synchronization of remote clocks: 100 ps via MWL and 50 via ELT Universal time scales: UTC, TAI Ranging: optical vs microwave and 1-way vs 2-way Atmospheric propagation delays: optical and microwave Monitoring of clocks in the GNSS network (GPS and Galileo) + test bed for technology towards future GNSS systems Luigi Cacciapuoti 30/03/2017 Slide 32

33 ACES Status o PHARAO FM delivered and integrated on the ACES baseplate o FCDP, ELT, and on-board GNSS receiver FMs delivered for integration o MWL FM and SHM PFM will be completed, tested and delivered by mid 2017 o Pre-IST tests completed in Nov o ACES FM tests already started and continued all across 2017 o MWL GTs: First terminal deployed in PTB in Nov and remotely monitored since then Remaining fixed terminals to be deployed by mid 2018 o ACES launch: mid months: commissioning/calibration 12 to 30 months: routine science phase Luigi Cacciapuoti 30/03/2017 Slide 33

34 Beyond ACES: Space Optical Clocks Atomic clock fractional frequency instability at the quantum projection noise limit: σσ yy ττ = 1 ππ νν 1 νν 0 NN aaaa TT cc ττ o o ν 1Hz, limited by the interaction time N at 10 6, limited by cooling and trapping techniques, collisions, etc. From the microwave to the optical domain o Frequency instability is inversely proportional to ν0: optical transitions show a potential increase of almost 5 orders of magnitude Microwave fountain clocks: σσ yy ττ = ττ 1/2 Optical clock: σσ yy ττ = ττ 1/2 o Accuracy: Technical issues and solutions o Measurements of optical frequencies fs frequency-comb generator o Recoil and Doppler effect trapped ion clock or lattice clock o Reference oscillator noise better clock lasers and reference cavities SOC as ACES follow-on mission Sr lattice clock with fractional frequency instability and inaccuracy Luigi Cacciapuoti 30/03/2017 Slide 34

35 SOC Lasers 461 nm 461 nm distribution 689 nm 813 nm 698 nm 689 nm Cavity Repumper Repumper Lock unit Luigi Cacciapuoti 30/03/2017 Slide 35

36 SOC Transportable Clock 163x99x60 cm Luigi Cacciapuoti 30/03/2017 Slide 36

37 SOC Status and Way Forward o Sr clock physics package completed and transported to PTB for clock characterization o Sr clocks at SYRTE and PTB below , both for stability and accuracy o Technology development activities for reaching TRL 4-5 on lasers started (TRP): Sr cooling lasers Sr lattice laser at the magic wavelength Clock control unit o Development of high-finesse cavity for the Sr clock laser + environmental tests started (GSTP) o SOC transportable clock to be used in ACES for geodesy studies o Phase A study of the SOC mission on the ISS to just started o Phase B study as part of the SciSpace programme to be approved by PB 163x99x60 cm Luigi Cacciapuoti 30/03/2017 Slide 37

38 Thanks for your attention Luigi Cacciapuoti 30/03/2017 Slide 38