presented by Wei-Tou Ni, Purple Mountai n Observatory, Chinese Academy of Scienc es, Nanjing 1 ASTROD and ASTROD I: Deep- ASTROD and ASTROD I: Deep- Space Laser Ranging Missions Space Laser Ranging Missions ASTROD: ASTRODYNAMICAL SPACE T EST OF RELATIVITY USING OPTICA L DEVICES ASTROD I --- A FIRST STEP OF A STRODYNAMICAL SPACE TEST OF RE LATIVITY USING OPTICAL DEVICES
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Presented by Wei-Tou Ni, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 1 ASTROD and ASTROD I: Deep- Space Laser Ranging Missions ASTROD:
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presented by Wei-Tou Ni, Purple Mountain Observatory, Ch
inese Academy of Sciences, Nanjing 1
ASTROD and ASTROD I: Deep-ASTROD and ASTROD I: Deep-Space Laser Ranging MissionsSpace Laser Ranging Missions
ASTROD: ASTRODYNAMICAL SPACE TEST OF RELATIVITY USING OPTICA
L DEVICES
ASTROD I --- A FIRST STEP OF ASTRODYNAMICAL SPACE TEST OF RELATI
VITY USING OPTICAL DEVICES
2006.04. 21. ASTROD & ASTROD I: Deep-Space Laser Ranging Missions 2ASTROD study team
Current ASTROD Collaborators Current ASTROD Collaborators Purple Mountain Obs, CAS Wei-Tou Ni, Gang Bao, Guangyu Li, H-Y Li, A. Pulido Patón, J. Shi, F. Wang, Y. Xia, Jun YanCAST, Li Wang, Hou,
Zhang, ...IP, CAS, Y-X Nie, Z. WeiYunnan Obs, CAS, Y.Xiong ITP, CAS, Y-Z Zhang Nanjing U Tianyi HuangTsing Hua U Sachie ShiomiNanjing A & A U H. WangNanjing N U, X. Wu, C. Xu H S & T U, Ze-Bing Zhou
ZARM, Bremen Hansjörg Dittus Claus Lämmerzahl Stephan Theil Imperial College Henrique Araújo Diana Shaul Timothy SumnerCERGA J-F Mangin Étienne Samain ONERA Pierre TouboulHumboldt U, Berlin Achim Peters
U Düsseldorf Stephan Schiller Andreas Wicht Max-Planck, Gårching Albrecht RüdigerTechnical U, Dresden Sergei Klioner Soffel U Missouri-Columbia Sergei KopeikinIAA, RAS George Krasinsky Elena PitjevaNanyang U, Singapore H-C Yeh
2006.04. 21. ASTROD & ASTROD I: Deep-Space Laser Ranging Missions 3ASTROD study team
AASTRODSTRODynamical ynamical SSpace pace TTest of est of RRelativity using elativity using OOptical ptical DDevicesevices
Sun
Inner Orbit
Earth Orbit
Outer OrbitLaunch Position
. Earth (800 days after launch)
L1 point
Laser Ranging
S/C 2
S/C 1
2006.04. 21. ASTROD & ASTROD I: Deep-Space Laser Ranging Missions 4ASTROD study team
OBJECTIVEOBJECTIVE ASTRODASTROD
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.
2006.04. 21. ASTROD & ASTROD I: Deep-Space Laser Ranging Missions 5ASTROD study team
ASTROD I: Two-Way Interferometric and ASTROD I: Two-Way Interferometric and Pulse Laser Ranging between Pulse Laser Ranging between
Spacecraft and Ground Laser StationSpacecraft and Ground Laser Station
Testing relativistic gravity with 3-order-of-magnitude improvement in sensitivity;
Astrodynamics & solar-system parameter determination improved by 1-3 orders of magnitude;
Improving gravitational-wave detection compared to radio Doppler tracking (Auxiliary goal).
2006.04. 21. ASTROD & ASTROD I: Deep-Space Laser Ranging Missions 6ASTROD study team
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).
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)
2006.04. 21. ASTROD & ASTROD I: Deep-Space Laser Ranging Missions 7ASTROD study team
International Collaboration PeriodInternational 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
Aimed accuracy of PPN space parameter γ for Aimed accuracy of PPN space parameter γ for
various ongoing / proposed experiments. various ongoing / proposed experiments. The types of experiments are given in the parentheses. The types of experiments are given in the parentheses.
Weaklight Phase LockingWeaklight 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 GOALASTROD GOALTesting relativistic gravity and the fundamental law
s 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.
Uncertainties of Determining Solar Uncertainties of Determining Solar Quadrupole Parameter J2 as a function of Quadrupole Parameter J2 as a function of
Schematic Diagram of the Schematic Diagram of the ASTROD I Spacecraft: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.
PayloadPayload (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 I Drag-free ControlASTROD I Drag-free Control
Hongying Li from PMO is in Bremen studying and working with Stephan Theil, Hansjoerg Dittus, and Claus Laemmerzahl to work out a preliminary drag-free control for ASTROD I.
Paper to be presented in the forthcoming COSPAR general assembly.
Testing relativistic gravity and the fundamental laws of spacetime with three-order-of-magnitude improvement in sensitivity; gamma to 10-7 or better, beta to 10-7, J
2 to 10-9, asteroid masses to 10-3 fraction Improving the sensitivity in the 5 µHz - 5 mHz low fre
quency gravitational-wave detection by several times; Initiating the revolution of astrodynamics with laser ra
nging in the solar system, increasing the sensitivity of solar, planetary and asteroid parameter determination by 1-3 orders of magnitude.