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Status of the ACES mission - IN2P3

Moriond Workshop, March 2003. Gravitational Waves and Experimental Gravity . Status of the aces mission The aces system The aces payload : - space clocks : PHARAO and SHM. - on-board comparisons - space-ground clocks comparisons with the microwave link MWL. ISS orbit determination The operations and coordination of aces ground users Moriond Workshop Les Arcs , 22-29 March 2003 1. The aces system PHARAO : Cold Cs atoms clock PHARAO XPLC SHM SHM : Space Hydrogen Maser FCDP : Frequency Comparison and Distribution Package FCDP XPLC : External payload computer TM PDU : Power distribution unit MWL space PDU. segment TC. ISS MWL : Microwave Link ASOC ASOC : aces control and mission center MWL ground Specific needs : terminals Precise ISS orbit determination aces payload microvibrations level Moriond Workshop Les Arcs , 22-29 March 2003 2.

Status of the ACES mission The ACES system ... (Timetech, Kayser-Threde, Germany) ... Phase comparator Typical MWL

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Transcription of Status of the ACES mission - IN2P3

1 Moriond Workshop, March 2003. Gravitational Waves and Experimental Gravity . Status of the aces mission The aces system The aces payload : - space clocks : PHARAO and SHM. - on-board comparisons - space-ground clocks comparisons with the microwave link MWL. ISS orbit determination The operations and coordination of aces ground users Moriond Workshop Les Arcs , 22-29 March 2003 1. The aces system PHARAO : Cold Cs atoms clock PHARAO XPLC SHM SHM : Space Hydrogen Maser FCDP : Frequency Comparison and Distribution Package FCDP XPLC : External payload computer TM PDU : Power distribution unit MWL space PDU. segment TC. ISS MWL : Microwave Link ASOC ASOC : aces control and mission center MWL ground Specific needs : terminals Precise ISS orbit determination aces payload microvibrations level Moriond Workshop Les Arcs , 22-29 March 2003 2.

2 The aces payload Moriond Workshop Les Arcs , 22-29 March 2003 3. aces on ISS. Launch ULF-3 end of 2006. COLUMBUS module Express Pallets aces . LOCATION. Moriond Workshop Les Arcs , 22-29 March 2003 4. aces PAYLOAD. (Astrium, France and Germany). MWL ANTENNAS. PHARAO. PDU. HEAT PIPES. BGU. MWL. SHM. XPLC. PHARAO CESIUM TUBE. PHARAO - OLS. Volume 1 m3 Mass 225 kg Power 400 W. Moriond Workshop Les Arcs , 22-29 March 2003 5. aces SPACE CLOCKS : PHARAO & SHM. Moriond Workshop Les Arcs , 22-29 March 2003 6. aces space clocks performance PHARAO stability better than y( ) = 10-13. -1/2 (in frequency). x( ) = 10-14. +1/2 (in time). PHARAO accuracy target : 10-16.

3 SHM stability better than PHARAO stability for mid-term PHARAO. -13 PHARAO. 10 100 SHM. SHM 12 ps @ 1 day -14. 10 10. x( ) [ps]. 3. 10-16 @ 1 day y( ). -15. 10 1. -16. 10 0,1. -17. 10 0,01. -1 0 1 2 3 4 5 6 7 -1 0 1 2 3 4 5 6 7. 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10. [s] [s]. Moriond Workshop Les Arcs , 22-29 March 2003 7. SHM PHYSICS PACKAGE. (Neuch tel Observatory, Switzerland). physics package cut view PTFE storage bulb collimator cavity thermal shield & c-field sapphire storage bulb microwave cavity cavity magnetic shields (4x). thermal shield external magnetic shield vacuum main structure assembly hydrogen beam assembly dissociator assembly Moriond Workshop Les Arcs , 22-29 March 2003 8.

4 SHM DESIGN. Magnetic shield hydrogen distribution RF oscillator Electronic package ion pump high voltage supply ion pump ! Thermal sensitivity ( f/f 10-15 per C), magnetic control ( 1 G nT). Moriond Workshop Les Arcs , 22-29 March 2003 9. PHARAO CESIUM TUBE DESIGN. (SODERN, France). ATOMIC STATE. PREPARATION DETECTION. REGION REGION. Cs RESERVOIR. COOLING. REGION MICROWAVE. INTERROGATION. REGION. !UHV : a few 10-10 torr ION PUMP. !Cavity temperature control ( C), magnetic control (< 1 G nT). Moriond Workshop Les Arcs , 22-29 March 2003 10. PHARAO DESIGN. CESIUM TUBE. PHARAO. COMPUTER. (EREMS). ION PUMP. MICROWAVE. SOURCE. OPTICAL LASER SOURCE. Moriond Workshop Les Arcs , 22-29 March 2003 11.

5 OPTICAL LASER SOURCE DESIGN. (SODERN, France). Alignment both in air and under vacuum Redundancy of laser diodes Moriond Workshop Les Arcs , 22-29 March 2003 12. EXTENDED CAVITY LASER DESIGN. (SODERN, France). ! High spectral purity laser diode for laser cooling and clock signal detection ECL breadboard test Moriond Workshop Les Arcs , 22-29 March 2003 13. MICROWAVE SOURCE DESIGN. (Thal s,Cemac, France). !High spectral purity microwave interrogation signal (@ GHz) to avoid any degradation of PHARAO frequency stability " High performance quartz oscillator ! stability 7. 10-14 @ 1 s " Microwave source detail Moriond Workshop Les Arcs , 22-29 March 2003 14.

6 PHARAO GROUND TESTING EQUIPMENT. (CNES, France). Vacuum chamber for PHARAO tests Moriond Workshop Les Arcs , 22-29 March 2003 15. Clocks comparisons in space : the FCDP . and the SERVO LOOPS. Moriond Workshop Les Arcs , 22-29 March 2003 16. The FCDP and the Servo loops . PHARAO XPLC SHM. MICRO CONTROLER. OLS. H Resonator PHARAO. -13 SHM. 10. CS Resonator aces clocks UGB. DDS2 FCDP DDS GHz -14. 10. y( ). -15. 100 MHz 100 MHz 10. DDS1 MWL 10 MHz FCDP and servo loops breadboard -16. Space terminal 10. 10( timetech , -1. 10. 0. 10 Kayser-Threde, 1. 10. 2. 10. 3. 10 Germany). 4. 10 10. 5 6 7. 10. 10 MHz [s]. Short term servo loop : improvement of PHARAO mid-term stability Long term servo loop : correction of SHM frequency drifts !

7 The signal delivered to the ground has the stability of the best clock and PHARAO accuracy Moriond Workshop Les Arcs , 22-29 March 2003 17. Space ground clocks comparisons with the microwave link MWL. All aces major scientific objectives rely on space ground comparisons : Short term comparisons (special relativity tests : c/c). Long term comparisons (general relativity tests : red shift, variation). Moriond Workshop Les Arcs , 22-29 March 2003 18. Clocks comparisons with MWL. " Low orbit of ISS : 400 km " Period : 90 min " Mean visibility duration : 300 s Comparison sessions with aces clocks for different ground clocks : Ground clock A. 90 min 300 s Ground clock B.

8 Ground clock C. Ground clock D. time 1 day Non-common view comparisons Common-view comparisons Moriond Workshop Les Arcs , 22-29 March 2003 19. MWL PERFORMANCE. STABILITY : PHARAO. 100. SHM. MWL. 10. x( ) [ps]. 1. 6 ps @ 1 day 0,1. ps over 1 pass -1 0 1 2 3 4 5 6 7. 10 10 10 10 10 10 10 10 10. [s]. ACCURACY : No need (time interval comparisons only). But the MWL ground terminal delays will be calibrated with an uncertainty below 100 ps Moriond Workshop Les Arcs , 22-29 March 2003 20. COMPARISON BETWEEN TWO DISTANT CLOCKS. TROPOSPHERIC DELAY. (temperature, humidity) ! 10 ns Electrical reference point IONOSPHERIC DELAY. V (TEC, varies as 1/f2 ) ! 10 ns SPACE INSTRUMENT.

9 MULTI-PATH EFFECT. multipath (distance, reflectivity of spurious reflectors). ionosphere INSTRUMENTAL DELAYS. (temperature, frequency and power of signals, incidence angle, .) ! 100 ps/K. troposphere RELATIVISTIC EFFECTS. (Position and velocities of space and ground clocks ). ! 1st order Doppler effect ! 2. 10-5. GROUND TERMINAL. ! 2nd order Doppler effect ! 3. 10-10. Electrical reference point ! Sagnac effect ! 7. 10-13. ! Gravitational shift ! 4. 10-11. Moriond Workshop Les Arcs , 22-29 March 2003 21. CHARACTERISTICS OF MWL. ( timetech , Kayser-Threde, Germany). Two way technique in Ku band : Down link @ 15 GHz ( W). Up link @ 13,5 GHz (4 W). ! removal of troposphere, 1st order Doppler aces clock instrumental delays.

10 Additional S band down link (@ GHz - W). ! for TEC determination Phase comparisons in space and on ground Phase PN code modulation : ! removal of 2 phase ambiguity Carrier phase and code phase measurements (1 measurement / s) both in space and on the ground Earth clock Data link (2 kBits/s in S-band down link). ! to obtain clock comparison results in real time 4 simultaneous ground users capability for common view comparisons Moriond Workshop Les Arcs , 22-29 March 2003 22. DESIGN AND REALIZATION OF MWL. ( timetech , Kayser-Threde, Germany). phase comparator MWL space segment breadboard Main constraints : Typical MWL. Multipaths ground terminal Temperature sensitivity and calibration Moriond Workshop Les Arcs , 22-29 March 2003 23.


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