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ASTROD and ASTROD I: Deep-Space Laser Ranging Missions

ASTROD and ASTROD I: Deep-Space Laser Ranging Missions. ASTROD : ASTROD YNAMICAL S PACE T EST OF R ELATIVITY USING O PTICAL D EVICES ASTROD I --- A FIRST STEP OF ASTRODYNAMICAL SPACE TEST OF RELATIVITY USING OPTICAL DEVICES. Current ASTROD Collaborators. ZARM, Bremen Hansjörg Dittus

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ASTROD and ASTROD I: Deep-Space Laser Ranging Missions

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  1. ASTROD and ASTROD I: Deep-Space Laser Ranging Missions ASTROD:ASTRODYNAMICAL SPACE TEST OF RELATIVITY USING OPTICALDEVICES ASTROD I --- A FIRST STEP OFASTRODYNAMICAL SPACE TEST OF RELATIVITY USING OPTICALDEVICES presented by Wei-Tou Ni, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing

  2. Current ASTROD Collaborators ZARM, Bremen Hansjörg Dittus Claus Lämmerzahl Stephan Theil Imperial College Henrique Araújo Diana Shaul Timothy Sumner CERGA J-F Mangin Étienne Samain ONERA Pierre Touboul Humboldt U, Berlin Achim Peters U Düsseldorf Stephan Schiller Andreas Wicht Max-Planck, Gårching Albrecht Rüdiger Technical U, Dresden Sergei Klioner Soffel U Missouri-Columbia Sergei Kopeikin IAA, RAS George Krasinsky Elena Pitjeva Nanyang U, Singapore H-C Yeh Purple Mountain Obs, CAS Wei-Tou Ni, Gang Bao, Guangyu Li, H-YLi, A. Pulido Patón, J. Shi, F. Wang, Y. Xia, Jun Yan CAST, Li Wang, Hou, Zhang, ... IP, CAS,Y-X Nie,Z. Wei Yunnan Obs, CAS, Y.Xiong ITP, CAS, Y-Z Zhang Nanjing U Tianyi Huang Tsing Hua USachie Shiomi Nanjing A & AUH. Wang Nanjing N U,X. Wu, C. Xu H S & T U, Ze-Bing Zhou ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  3. S/C 2 S/C 1 Laser Ranging Inner Orbit Sun Launch Position Outer Orbit Earth Orbit . L1 point Earth (800 days after launch) ASTRODynamical Space Test of Relativity using Optical Devices ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  4. OBJECTIVEASTROD • Testing relativistic gravity and the fundamental laws of spacetime with 5 order-of-magnitude improvement in sensitivity; • Improving the sensitivity in the 5 µHz - 5 mHz low frequency gravitational-wave detection by several orders of magnitude as in LISA but shifted toward lower frequencies; • Revolutionize the astrodynamics with laser ranging in the solar system, increasing the sensitivity of solar, planetary and asteroid parameter determination by 3-4 orders of magnitude. ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  5. ASTROD I: Two-Way Interferometric and Pulse Laser Ranging between Spacecraft and Ground Laser Station • Testing relativistic gravity with 3-order-of-magnitude improvement in sensitivity; • Astrodynamics & solar-systemparameter determination improved by 1-3 orders of magnitude; • Improving gravitational-wave detection compared to radio Doppler tracking (Auxiliary goal). ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  6. 1993 Laser Astrodynamics was proposed to study the relativistic gravity and to explore the solar system in 2nd William Fairbank Conference (Hong Kong) and in the International workshop on Gravitation and Fifth Force (Seoul). • ASTROD mission concept – 7th Marcel Grossmann (Stanford, 1994) and 31st COSPAR (Birmingham, 1996) • Ġ /G and solar-system mass loss measurement (Seoul, 1996) • G-wave sensitivity studied; Mini-ASTROD and Super-ASTROD proposed (1st TAMA Meeting, Tokyo, 1997) • Lab and Mission Concept Studies (1993-2000) ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  7. International Collaboration Period • 2000: ASTROD proposal submitted to ESA F2/F3 call (2000) • 2001: 1st International ASTROD School and Symposium held in Beijing; Mini-ASTROD study began • 2002: Mini-ASTROD (ASTROD I) workshop, Nanjing • 2004: German proposal for a German-China ASTROD study collaboration approved • 2005: 2nd International ASTROD Symposium of these combined meetings (June 2-3, Bremen, Germany) • 2004-2005: ESA-China Space Workshops (1st &2nd, Noordwijk & Shanghai), potential collaboration discussed • 2006: Collaboration Proposal Applied to Sino-German Center; 3rd ASTROD Symposium (July 14-16, Beijing) before COSPAR (July 16-23) in Beijing • May- September, 2006: Joint ASTROD I proposal to be submitted to ESA call for Cosmic Vision proposals ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  8. Gravitational wave strain sensitivity for ASTROD compared to LISA ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  9. Outgoing Laser beam Telescope Optical readout beam Dummy telescope Proof mass Large gap Incoming Laser beam ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  10. Orbit Simulation Assumptions • (1) The uncertainty due to the imprecision of the ranging devices: 1 ps one way (Gaussian) • (2) Unknown acceleration due to the imperfections of the spacecraft drag-free system: 10-17m/s2 & change direction randomly every 4 hr (~104s) [This is equivalent to (10-17m/s2)  (104s)1/2 = 10-15m/s2(Hz) ½ at 10-4Hz] ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  11. An error simulation for 2015 launching orbit ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  12. Anchoring Anchoring Dummy telescope Dummy telescope Proof mass Proof mass Housing Housing LASER Metrology LASER Metrology Telescope Telescope ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  13. Gaussian Fits & Propagation of Errors ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  14. Simulation for 3000 days ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  15. ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  16. Expected Mass-Loss Rate of the Sun Mechanism Fractional Rate -------------------------------------------------- Solar EM Radiation 7 Х 10-14/yr Solar Wind ~ 10-14/yr Solar Neutrino ~ 2Х 10-15/yr Solar Axion ~ 10-15/yr -------------------------------------------------- ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  17. Aimed accuracy of PPN space parameter γ for various ongoing / proposed experiments. The types of experiments are given in the parentheses. ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  18. Crucial Technology • 100 fW weaklight phase locking • Design and development of sunlight shield system • Design and development of drag-free system ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  19. The Results for 20 pW Power Beam Error Signal X: 20 s/div X: 50 ms/div Locked Y: 10 mV/div Y: 10 mV/div ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  20. Experemental Results presented by Wei-Tou Ni, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing

  21. Weaklight Phase Locking • Requirement: phase locking to 100 fW weak light • Achieved: phase locking of 2 pW weak light with 200 µW local oscillator • With pre-stabilization of lasers, improving on the balanced photodetection and lowering of the electronic circuit noise, the intensity goal should be readily be achieved • This part of challenge should be focussed on offset phase locking, frequency-tracking and modulation-demodulation to make it mature experimental technique (also important for deep space communication) • Weak light phase locking experiment re-started at PMO ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  22. Drag-free System R & D • Consists of a high-precision accelerometer/inertial sensor to detect non-drag-free motions and micro-thruster system to do the feedback to keep the spacecraft drag-free • Looking for collaboration with ONERA and Trento University to learn the R & D they have for accelerometer/inertial sensor • Collaboration with ZARM, Bremen University for feedback control and end-to-end spacecraft model • Collaboration with Imperial College on charge control of the proof mass ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  23. Design of Sunlight Shield System Sun shutter Narrow band filter FADOFfilter ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  24. Design of Sunlight Shield System • The sunlight shield system consists of a narrow-band interference filter, a FADOF (Faraday Anomalous Dispersion Optical Filter) filter, and a shutter • The narrow-band interference filter reflects most of the Sun light directly to space • The bandwidth of the FADOF filter can be 0.6-5 GHz • With the shutter, the Sun light should be less than 1 % of the laser light at the photodetector ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  25. Solar oscilla-tion modes ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  26. BISON network observations ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  27. μ ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  28. ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  29. 1-year amplitude modulation of solar oscillation for ASTROD • A joint/dedicated mission are under investigation ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  30. ASTROD GOAL • Testing relativistic gravity and the fundamental laws of spacetime with 5 order-of-magnitude improvement in sensitivity; • Improving the sensitivity in the 5 µHz - 5 mHz low frequency gravitational-wave detection by several orders of magnitude as in LISA but shifted toward lower frequencies; • Revolutionize the astrodynamics with laser ranging in the solar system, increasing the sensitivity of solar, planetary and asteroid parameter determination by 3-4 orders of magnitude. • Chance to detect solar g-mode oscillations ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  31. ASTROD I ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  32. ASTROD I: Two-Way Interferometric and Pulse Laser Ranging between Spacecraft and Ground Laser Station • Testing relativistic gravity with 3-order-of-magnitude improvement in sensitivity; • Astrodynamics & solar-systemparameter determination improved by 1-3 orders of magnitude; • Improving gravitational-wave detection compared to radio Doppler tracking (Auxiliary goal). ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  33. Typical Launch Trajectory of ASTROD I ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  34. Spacecraft Trajectory ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  35. Spacecraft-Venus Distance ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  36. Orbit Description • Launch via low earth transfer orbit to solar orbit with orbit period 300 days • First encounter with Venus at 118 days after launch; orbit period changed to 225 days (Venus orbit period) • Second encounter with Venus at 336 days after launch; orbit period changed to 165 days • Opposition to the Sun: shortly after 370 days, 718 days and 1066 days ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  37. Apparent Angles during 2 Solar Oppositions ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  38. Shapiro Time Delays ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  39. Orbit Simulation Assumptions • (1) The uncertainty due to the imprecision of the ranging devices: 10 ps one way (Gaussian) • (2) Unknown acceleration due to the imperfections of the spacecraft drag-free system: 10-15m/s2 & change direction randomly every 4 hr (~104s) [This is equivalent to (10-15m/s2)  (104s)1/2 = 10-13m/s2(Hz) ½ at 10-4Hz] ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  40. 3 Sets of Simulated Data(Total: 50 sets) ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  41. Uncertainties of Determining Gamma and Beta as a function of Epoch ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  42. Uncertainties of Determining Solar Quadrupole Parameter J2 as a function of Epoch ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  43. Gaussian Fit of 50 Determinations of Relativistic Parameters ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  44. Orbit Simulation Results • Determine the relativistic parameter γ to 10-7. • Determine the relativistic parameter β to 10-7 and others with improvement. • Improve the solar quadrupole moment parameter J2 determination by one order of magnitude, i.e., to 10-9. • Ġ /G to 10-13/yr ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  45. Black Surface FEEP Power Unit Optical Comb Optical Cavity Clock CW Lasers Thermal Control Electronics Telescope TIPO Pulse Laser Power Unit Black Surface FEEP Schematic Diagram of the ASTROD I Spacecraft ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  46. Schematic Diagram of the ASTROD I Spacecraft: • (i) Cylindrical spacecraft with diameter 2.5m, height 2m and cylindrical surface covered with solar panels, • (ii) In orbit, the cylindrical axis is perpendicular to the orbit plane with the telescope pointing toward the ground laser station. The effective area to receive sunlight is about 5m2 and can generate over 500 W of power. • (iii) The total mass of spacecraft is 300-350 kg. That of payload is 100-120 kg. • (iv) Science data rate is 500 bps. The telemetry rate is 5 kbps for about 9 hours in two days. ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  47. Payload (1) Laser systems for interferometric and pulse ranging (i) 2 (plus 1 spare) diode-pumped Nd:YAG laser (wavelength 1.064 m, output power 1 W) with a Fabry-Perot reference cavity: 1 laser locked to the Fabry-Perot cavity, the other laser pre-stabilized by this laser and phase-locked to the incoming weak light. (ii) 1 (plus 1 spare) pulsed Nd:YAG laser with transponding system for transponding back the incoming laser pulse from ground laser stations. (2) Quadrant photodiode detector (3) 380-500 mm diameter f/1 Cassegrain telescope (transmit/receive), /10 outgoing wavefront quality ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  48. Payload (4) Sunlight Shield System (5) Drag-free proof mass (reference mirror can be separate): 50  35  35 mm3 rectangular parallelepiped; Au-Pt alloy of extremely low magnetic suceptibility (<10-5); Ti-housing at vacuum 10-5Pa ; six-degree-of- freedom capacity sensing. (6) Cesium clock (7) Optical comb ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  49. One Way Laser rangingTime Transfer by Laser LinkTIPO Etienne Samain, Patrick Vrancken OCA, Gemini 2130 route de l’Observatoire 06460 Caussols, FRANCE Philippe Guillemot CNES Av Edouard Belin 31400 Toulouse, FRANCE Cheng Zhou (PMO) is in OCA studying and working on 3 ps event timer ASTROD & ASTROD I: Deep-Space Laser Ranging Missions

  50. Ground Station for the ASTROD I Mission at Yunnan Observatory ◆Introduction of Yunnan Observatory 1.2m Telescope＆ Its Laser Ranging System◆ Key Requirements of Ground Station for the Mission◆ Telescope Requirement: Pointing and Tracking Accuracy◆Atmospheric Turbulence Effects on Laser Ranging ◆ F. Song of Yunnan Observatory is collaborating with Y. Luo of PMO to study the laser acquisition and pointahead presented by Wei-Tou Ni, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing

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