Space Gravitational Wave Detection
in China
Yue-Liang Wu
University of Chinese Academy of Sciences (UCAS)
Kavli Institute for Theoretical Physics China (KITPC/ITP-CAS)
On behalf of Working Group on Space GWD/CAS
First eLISA Consortium Meeting
APC-Paris, France, Oct. 22-23, 2012
Strategic Goal of Space Science
in China: A Roadmap to 2050
-----------------------------------------------------------
Original breakthroughs should be made in
directly detecting black hole, dark matter,
dark energy, gravitational waves, …….
-- Space Sciences & Technology
in China: A Roadmap to 2050,
(Edt: H.D. Guo, J. Wu
Science Press & Springer, Beijing, 2010)
Space Science Strategy Pioneer Program,
(SSSPP/CAS)
• Leading Group
Director: H.J. Yin (Vice-President of CAS)
• National Scientific Committee of Space Science
Chairman: H.J. Yin
• Office of SSSPP
Director: Y.J. Yu (HQ CAS)
• National Space Science Center
Chairman: J. Wu (Director of Space Science &
Application Center)
Studies on GW Detection in China
Many workshops and meetings have been held in China
• Ground GW detection:
Australia-China collaboration
• ASTROD: suggested by Prof. W.D. Ni
• Space GW Detection of China (2008-2011):
Feasibility study on Space G-W Detection.
A suggestion on SGD program similar to LISA in
frequency range f ～1.0-10-2 Hz
• Working group on SGD mission for joining the
NGO Program (2012 - )
World-wide Future GW detection projects
Suggestion of Space GWD in China
• Feasibility study based on ALIA Mission
concept (2008-2010).
• Preliminary studies phase of CAS project for
began and a mission design (2010-2012).
• Ground based experiments in key technologies
and theoretical studies. Accepted as a part of
national program in 2011 and will be started in
the near future after a starting review (20112015) .
Chinese Mission Options (Inst. Appl. Math./CAS)
Mission Design

Assumptions:
1.
1.
Sensitivity of inertial sensor one order
better than that of LISA
(at higher frequency window)
Suppress shot noise by increasing laser
power and diameter of telescope
~1.5 order more sensitivity than LISA.
Sensitivity floor shifts to the right.
Baseline Design Parameters (Peter Bender , CQG, 21, S1203 (2004))
Options ( Inst. Appl. Math., CAS)
3L and 3H are currently preferred as far as
technology development is concerned
Main Scientific Purpose
Overlapped with LISA
• Sensitivity floor shifts to the right.
• Enhanced Intermediate mass black
holes (IMBH) detection
• Light seed Population III remnants
Almost equal mass coalescence
(High redshift)
•
Intermediate mass ratio spiral
(Low redshift)
Overlapped with BBO/DECIGO
 The major purpose of space
gravitational wave detection in
bandwidth between 0.1 and 1.0 Hz
is to search for the stochastic back
ground of gravitational waves
coming from the early university
• Primordial Gravitational Wave
Background (inflation, electroweak
transition, Population III stars core
collapse)
• Bursts from hypothetical
cosmological structures like cosmic
string and other topological defects
in the early Universe
Better IMBH Detection – Extra Sciences on offer
Main difference from LISA
Sensitivity floor shifts to the right.
Enhanced Intermediate mass black
holes (IMBH) detection
• Light seed Population III remnants
• Almost equal mass coalescence (High redshift)
• Intermediate mass ratio spiral (Low redshift)
Working Group on SGWD/CAS (2012)
Heads
W.R. Hu (Institute of Mechanics),
Y.L. Wu (Univ. of Chinese Academy of Sciences, UCAS).
Members
L.Q. Peng (Bureau of Basic Research Sciences),
C.F. Qiao and Y.S. Pu (Univ. of Chinese Acad. of Sci.),
R.Q. Lau (Institute of Applied Math.) ,
G. Jin and Q. Kang (Institute of Mechanics),
Y.X. Nie and Z.Y. Wei (Institute of Physics),
M. Li and Y.Z. Zhang (Institute of Theoretical Physics),
S.N, Zhang (Institute of High Energy Physics)
Z.L. Zhou and Y.T. Zhu(National Astronomy Observatory),
M.S. Zhan and L.S. Chen (Wuhan Institute of Phys. & Math.).
Possibility on Joining NGO Program
 Telescope of NGO (Nanjing Institute of
Astronomy and Optics Technology, CAS)
 Collaboration with MP Institute for
Gravitational Physics on Laser Interferometer
(Institute of Mechanics, CAS)
 Collaboration with Trento University for
inertial sensors (Huazhong University of Sci. &
Tech.)
 Others
Nanjing Institute of Astronomical & Optics
Technology –Space Telescope
Antarctic
telescope
LAMOST
Zerodur
mirror
SiC
Mirror
Critical Requirements for the
Telescope Subsystem
Parameter
1
2
Wavelength
Net Wave front quality of as built telescope subs
system over science field of view
Derived From
NGO
1064 nm
Pointing
l/20
RMS
1 pm /
3
Telescope subsystem optical path length stability
under specified environment
4
Field-of-View (Acquisition)
5
Field-of-View (Science)
6
Transmitted beam diameter on primary mirror
7
Entrance Mirror Diameter
8
Path length Noise/ Pointing
Acquisition
Hz 
4 
 
0.003  
 1   

    f   


where 0.0001 < f < 1 Hz
1 pm = 10-12 m

+/- 200 mrad
Orbits
+/- 7 mrad out-of-plane2
+/- 4.2 mrad in-plane
Shot noise/ Pointing
0.92·D
Noise/ pointing
200 mm
Entrance Pupil
Pointing
Entrance of beam or primary
11
Location of image of primary mirror (exit pupil)
Pointing
~10 cm (on axis) behind primary mirror
12
Pupil distortion
SNR
10%
13
Beam size on bench
short arm interferometer
5 mm
14
15
Mechanical length
Optical efficiency
Shot noise
350 mm
>0.85
16
Scattered Light
Displacement noise
< 10-10 of transmitted power
17
Telescope spacer variation
2.5 microns
Space Telescopes
— Utilize the Goddard Space Flight
Center design
Material and Fabrication
• Mirrors--- Zerodur
• Telescope spacer– SiC , Asymmetric
Quad-Pod design
• Wavefront quality realized in mirror lab.
Stability Test and Measurements
Cooperation Between AEI and IM/CAS
• Jointly develop the space laser
interferometer for NGO ;
• Share the future space laser interferometer
duty in NGO mission.
Space Interferometer
on the earth base
Institute of Mechanics/CAS
Institute of Physics/CAS
Wuhan Institute of Phys. & Math./CAS
HUST
Further Ground Based Experiments
1、Measurement of distance variation;
2、Noise evaluation;
3、Pointing control;
4、Phase lock;
5、Ranging tone system demo;
6、Sideband-sideband scheme demo;
7、TDI demo;
Laser metrology Demonstration System @ IMECH CAS
Two M-Z interferometers (equal arm)
Heterodyne detection
Offset frequency from 10kHz to 500kHz
Laser wave length 633nm
Isolated base
Clean room: class 1000
Thermal stabilized by air-condition
Laser metrology Demonstration System @ IMECH CAS
Noise Curve in
Power Spectra
Density
With Mirror-D fixed
0.1 - 0.5 nm/Hz1/2
within frequency band
between 0.15 m Hz
and 0.375 Hz
Mirror-D moved
sinusoidally, with a
period 100s.
1 - 3 nm/Hz1/2
between 0.15m Hz
and 0.01 Hz
Lower than 1 nm/Hz1/2
within from 0.01 Hz to
0.375 Hz
HUST
HUST
Cooperation Agreement between HUST and Univ. Trento
Goal of cooperative research
•Modeling and evaluation of the performances of inertial sensors for
GW missions
•Development of ground-based testing facilities, and research on
inertial sensors
•Design of some engineering components and their performance
verification
•Training of research groups
Contents of cooperative research
•Modeling and the analysis of spurious forces
•Developing torsion pendulum for ground-based tests
•Experimental verification of the noise model and sensor
performance
•Coupling between interferometer and inertial sensor
•Coupling between inertial sensor and drag-free control
Cooperation Agreement between HUST and Univ. Trento
Progress of Inertial sensor of LISA Pathfinder
 Performance research of inertial sensor using torsion pendulums
 Push to develop the inertial sensor engineering model
10-14 Nm/Hz1/2
Univ. Trento, Italy
PRL 91 (2003) 151101
PRL 103 (2009) 140601
PRL 108 (2012) 181101
28
Progress of HUST
•To develop a two-stage pendulum to test
performances of inertial sensor
•The facility can be used to simulate 2D
motions of the proof mass, which is important
to investigate cross-coupling of PM
9*10-14Nm/Hz1/2
Tu et al., CQG 27 (2010) 205016
Zhou et al., CQG 27 (2010) 175012
29
Inertial Sensor Development in HUST
School of Physics , HUST, China
fiber
frame & TM
Torsion Pendulum
Sensitive to torque
Inertial sensor
micro-operation
platform
box
turntable
Torsion Balance
Sensitive to direct
force
d0=152 um
Sensitive Direction
Two space experiments have been scheduled
Inertial Sensor
Huazhong University of Sci. & Tech. (HUST)
Progress:
Two-stage torsion pendulum, (Liu et al., CQG 2010)
10-10m/s2/√Hz for small gap 0.1mm (Tu et al., CQG 2010)
Next-step:
Fused-fiber suspension, thermal limit: 1fNm / √Hz at 2mHz
To determine differential shape and material proof mass (PM)
To measure the effects of PM with temperature, electric, magnetic
To investigate the cross-coupling between the DoF of PM
10 13
gold wire
suspension fiber
S 1N 2 N m Hz1 2
10 14
10 15
10 16
10 17
10 5
10 4
0.001
0.01
Frequency Hz
0.1
1
Others
 To be considered and discussed
Prospect
• Step I (2011~2015)
Ground studies on theoretical analyses
and key technology
• Step II (2016~2020+)
Space technology for a satellite of key
technology experiment
• Step III (2020+ ~ 2030+)
Satellite of GWD/CN or joining NGO
Thank You!