Presented by Wei-Tou Ni, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 1 ASTROD and ASTROD I: Deep- Space Laser Ranging Missions ASTROD:

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


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


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.


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).


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)


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

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


Gravitational wave strain sensitivity for ASTROD compared to LISA

1E-25

1E-24

1E-23

1E-22

1E-21

1E-20

1E-19

1E-18

1E-17

1E-16

1E-15

1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01

Frequency (Hz)

Gra

vita

tio

nal

Wav

e S

trai

n

LISA Bender extension

LISA, 1 yr int. time S/N=5

ASTROD, 1 yr int. time, S/N=5


Incoming Laser beam

Proof mass

Outgoing Laser beam

Optical readoutbeam

Large gap

Telescope

Dummy telescope

2006.04. 21. ASTROD & ASTROD I: Deep-Space Laser Ranging Missions 10

ASTROD study team

Orbit Simulation AssumptionsOrbit 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 study team

An error simulation for 2015 An error simulation for 2015 launching orbitlaunching orbit

0 500 1000 1500 2000 2500 3000

-2.5x10-11

-2.0x10-11

-1.5x10-11

-1.0x10-11

-5.0x10-12

0.0

5.0x10-12

1.0x10-11

1.5x10-11

2.0x10-11

Err

or

(s

)

Time (day)

Outer


ASTROD study team


ASTROD study team

Gaussian Fits & Propagation of Gaussian Fits & Propagation of ErrorsErrors


ASTROD study team

Simulation for 3000 daysSimulation for 3000 days


ASTROD study team


ASTROD study team

Expected Mass-Loss Rate Expected Mass-Loss Rate of the Sun 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 study team

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.


ASTROD study team

Crucial TechnologyCrucial Technology100 fW weaklight phase lockingDesign and development of sunlig

ht shield systemDesign and development of drag-fr

ee system


ASTROD study team

The RThe Results for esults for 20 pW Power Beam 20 pW Power Beam

Y: 10 mV/div

X: 20 s/div X: 50 ms/div

Y: 10 mV/div

Error Error SignaSignall

Locked



Experemental ResultsExperemental ResultsLow Power Beam Intensity (measured using oscilloscope)

20 nW 2 nW200 p

W20 pW

2 pW

High Power Beam Intensity (mW)

2 2 0.2 0.2 0.2

Low Power Intensity Measured by Lock-in Amplifier

20.9 nW 2.15 nW 153 ~247 pW

N/A N/A

r.m.s. Error signal Vrms （ mV ） 2.01 2.06 2.29 2.03 2.70

r.m.s Phase error （ rad ） 0.0286 0.057 0.2 0.16 0.29

Phase-locking time Longer than observation

duration

Longer than

observation duration

> 2 hours

> 2 hours

1.5 mins


ASTROD study team

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 study team

Drag-free System R & DDrag-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 study team

Design of Sunlight Shield SystemDesign of Sunlight Shield System

Narrow band filterFADOF filter

Sun shutter


ASTROD study team

Design of Sunlight Shield SystemDesign 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 study team

Solar Solar oscilla-oscilla-

tion tion modesmodes


ASTROD study team

BISON BISON network network

observationsobservations


ASTROD study team

μ


ASTROD study team


ASTROD study team

1-year amplitude modulation of solar oscillation for ASTROD

A joint/dedicated mission are under investigation


ASTROD study team

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.

Chance to detect solar g-mode oscillations


ASTROD study team

ASTROD IASTROD I


ASTROD 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).


ASTROD study team

Typical Launch TrajectoryTypical Launch Trajectory of of ASTROD IASTROD I


ASTROD study team

Spacecraft TrajectorySpacecraft Trajectory


ASTROD study team

SpacecraftSpacecraft-Venus-Venus Distance Distance


ASTROD study team

Orbit DescriptionOrbit DescriptionLaunch via low earth transfer orbit to solar

orbit with orbit period 300 daysFirst 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 study team

Apparent Angles during 2 Solar OppositionsApparent Angles during 2 Solar Oppositions


ASTROD study team

Shapiro Time DelaysShapiro Time Delays


ASTROD study team

Orbit Simulation AssumptionsOrbit 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 study team

3 Sets of 3 Sets of Simulated Simulated

DataData(Total: 50 (Total: 50

sets)sets)


ASTROD study team

Uncertainties of Determining Gamma Uncertainties of Determining Gamma and Beta as a function of Epochand Beta as a function of Epoch


ASTROD study team

Uncertainties of Determining Solar Uncertainties of Determining Solar Quadrupole Parameter J2 as a function of Quadrupole Parameter J2 as a function of

EpochEpoch


ASTROD study team

Gaussian Fit of 50 Determinations Gaussian Fit of 50 Determinations of Relativistic Parametersof Relativistic Parameters


ASTROD study team

Orbit Simulation ResultsOrbit Simulation ResultsDetermine 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 study team

Schematic Diagram Schematic Diagram of the ASTROD I Spacecraftof the ASTROD I Spacecraft

Thermal Control

Black Surface

Black Surface

FEEP

Power Unit

Power Unit

Pulse Laser

CW LasersClockOptical Comb

Optical Cavity

FEEP

TIPO

Electronics

Telescope


ASTROD study team

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.


ASTROD study team

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 study team

PayloadPayload (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 10-5 Pa ; six-degree-of- freedom capacity sensing.

(6) Cesium clock(7) Optical comb

2006.04. 21. ASTROD & ASTROD I: Deep-Space Laser Ranging Missions ASTROD study team

One Way Laser rangingOne Way Laser rangingTTime ime TTransfer by ransfer by LLaser aser LLinkink

TIPOTIPOEtienne Samain, Patrick VranckenOCA, Gemini2130 route de l’Observatoire06460 Caussols, FRANCE

Philippe GuillemotCNESAv Edouard Belin31400 Toulouse, FRANCE

Cheng Zhou (PMO) is in OCA studying and working on 3 ps event timer



Ground Station for the ASTROD IGround Station for the ASTROD I Mission at Yunnan Observatory Mission at Yunnan Observatory

◆◆ Introduction of Yunnan Observatory 1.2m TelescopeIntroduction of Yunnan Observatory 1.2m Telescope

＆＆ Its Laser Ranging SystemIts Laser Ranging System

Key Requirements of ◆ Key Requirements of ◆ Ground Station for the Mission

Telescope Requirement: Pointing and Tracking Accuracy◆ 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


ASTROD study team

◆◆ Yunnan Observatory 1.2 mTelescopeYunnan Observatory 1.2 mTelescope

Its Laser Ranging SystemIts Laser Ranging System

Coordinates:Coordinates:

Latitude Latitude

25.0299 25.0299 N N

Longitude Longitude

102. 7972 102. 7972 E E

Elevation Elevation

1991.83 m1991.83 m


ASTROD study team

Optics Design for ASTROD IOptics Design for ASTROD I

Albrecht Ruediger and Haitao Wang : Bremen talk 2005, and ASTROD2006 talk


ASTROD study team

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.


ASTROD study team


ASTROD study team


ASTROD study team

Theoretical FoundationsTheoretical Foundations

Chongming Xu: 2nd order light deflectionKopeikin, Klioner, SoffelTianyi Huang: time scalesPeng Dong, Yi Xie: 2nd order Post-Newtonian

Approximation and Astrodynamics



Acceleration disturbances and requirements for ASTROD I

Sachie Shiomi and Wei-Tou Ni

Center for Gravitation and Cosmology

Dept. of Phys., Tsing-Hua Univ., Hsinchu


ASTROD study team


ASTROD study team



ASTROD I:ASTROD I:Charging Simulation & Charging Simulation &

DisturbancesDisturbancesGang Bao(1,2), Diana N A Shaul(3), Henrique M Araujo(3), Wei-Tou

Ni(1,2), Tim J Sumner(3) & Lei Liu(1)

(1)Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008

(2)National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012

(3)Department of Physics, Imperial College London, London, SW7 2BZ, UK

2nd International ASTROD Symposium, 2-3 June 2005, ZARM, Bremen, Germany


ASTROD study team

GEANT4 Charging SimulationGEANT4 Charging Simulation

Chargi ng for Protons

Q(t) = 26. 2 +e/ s

-20

0

20

40

60

80

100

120

140

160

180

0 2 4 6 8

Ti me(s)

Char

ge(+

e)


ASTROD study team

Launcher and Mission Launcher and Mission LifetimeLifetime

Launcher: Long March IV B (CZ-4B)

Mission Lifetime:

3 years (nominal)

8 years (extended)


ASTROD study team

OUTLOOKOUTLOOK ASTRODASTROD I I

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.

Optimistic date of launch: 2015


ASTROD study team

Spacecraft and Mission Analysis Spacecraft and Mission Analysis StudyStudy

Li Wang, Hou, Zhang, ... from China Academy of Space Technology are working on it


ASTROD study team

Thank you!

Documents

Presented by Wei-Tou Ni, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 1 ASTROD and ASTROD I: Deep- Space Laser Ranging Missions ASTROD: