1. DECIGO Pathfinder Masaki Ando
(Department of Physics, The University of Tokyo)
and DECIGO Pathfinder working Group
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

2. Introduction (1) DECIGO roadmap LPF LISA Ad. LIGO LCGT
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

3. DECIGO-PF (1) DECIGO Pathfinder (DPF) DECIGO-PF
　　One small satellite
(Weight: ~ kg, Orbit: around the earth)
10cm Fabry-Perot cavity formed by free masses
Stabilized laser source
Drag-free control system
Gravitational-wave observation
　　　(5) Observation for low-frequency (0.1-1Hz) GWs
　　 Mid.-scale BHs at the Galactic center　
Test and demonstration for DECIGO
　　　(1) Drag-free control system
　　　(2) Laser source and its stabilization system
(3) Control of Fabry-Perot interferometer
(4) Launch-lock system
Local Sensor
Actuator
Thruster
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

4. DECIGO-PF (2) DPF diagram Drag-free control Local sensor signal
　　 Feedback to thrusters/wheels
Mission weight : ~100kg
Mission space : ~90 x 90 x 90 cm
Fabry-Perot interferometer
　 Finesse : 100
　 Length : 10cm
　Test mass : 1kg
Signal extraction by PDH
Laser source
Nd:YAG laser (1064nm)
Power : 25mW
Freq. stab. by reference cavity
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

5. DECIGO-PF (3) DPF sensitivity Laser source : 1064nm, 25mW
(Preliminary parameters)
Laser source : 1064nm, 25mW
IFO length : 10cm
Finesse : 100, Mirror mass : 1kg
Q-factor : 105, Substrate: Fused Silica
Temperature : 293K
Satellite mass : 100kg, Area: 1m2
Altitude: 750km
Thruster noise: 0.1μN/Hz1/2
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

6. DECIGO-PF (4) DPF orbit Selection of DPF orbit
　 　 Launch chance (Cost, Launch window)
Operation (Power supply, Telemetry)
　　 Stability, Noises
750km
Low-earth orbit
Altitude 750km
Polar sun synchronous orbit
DPF
Sun
No eclipse
 Full-time operation
Higher altitude will be desirable
　　 to reduce the effect of the earth
(Earth’s gravity, terrestrial magnetism,
residual atmosphere)
Earth
Depends on launch chance
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

7. DECIGO-PF (5) Gravity-gradient noise Cut-off at 0.03Hz:
originates in the model resolution
 Unknown at higher frequency
This will not be a problem:
higher-order contribution will be negligible
order of ~(Re/r) n
Observe gravity field
with higher resolution?
Global gravity field model
Public data obtained by GRACE
　 Up to 150th-order
in spherical harmonics
Satellite velocity of 5km/sec
 Estimate the noise spectrum
Assume 2% vertical-horizontal coupling
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

8. DECIGO-PF (6) Geomagnetic noise Two effect by geomagnetic field:
Satellite motion in magnetic field
　 Fluctuation in geomagnetic field
Satellite
self-field
Geomagnetic field model
IGRF-10 model
(10th generation of International
Geomagnetic Reference Field)
Altitude 750km
Satellite velocity of 5km/sec
Effect of geomagnetic field:
smaller than satellite self-field ~10-7 T
 noise level ~ 1.5 x m/s2/Hz1/2
Magnetic-field noise
Fluctuation in geomagnetic field
Public data at Esashi observatory
1 sample/min data
 Extrapolate for higher frequency
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

9. DECIGO-PF (7) Survey of noise sources Magnetic field Residual Gas
Force
Acceleration
Acceleration noise
Displacement noise
Magnetic field
Residual Gas
Thermal radiation
Laser freq. noise
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

10. DECIGO-PF (8) Comparison with other detectors
Only a little observation data at low-frequency band
　　　 Doppler tracking: h ~10-15 　( Hz)
Pulsar timing: h ~10-14 　(10-8 Hz)
Inspiral of
Massive BH
DPF limit
LISA
NS inspiral
Galactic binary
Core-collapse
super nova
ScoX-1
(1yr)
Galactic binary
Foreground noise
Pulsar
　　 (1yr)
GWs from
Early universe
(Wgw=10-14)
DECIGO
LCGT
Gravity-gradient
noise for terrestrial detectors
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

11. DECIGO-PF (9) DPF targets Quasi-nomal mode oscillation of massive BH
h ~ , f ~ 0.3 Hz
Distance 1Mpc, m = 105 Msun
Binary inspiral of mid.-scale BHs
h ~ , f ~ 4 Hz
Distance 10kpc, m = 103 Msun
Events at Galactic center
will be detectable with SNR~5
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

12. DPF status (1) Brief history
2004 December
　　　Call for suggestions of small satellite mission by JAXA 2005  January
　　　Submit a proposal of small GW detector mission
~30 missions were submitted 2006 October
Call for proposals of small satellite mission by JAXA
2006 November
　　　Submit a proposal of GW-detector satellite as DECIGO pathfinder (DPF)
16 missions were accepted as working groups
(10 science, 6 engineering missions), including DPF
2007 April
Review meeting for these missions
2007 August
DPF has been selected as one of 5 Pre-Phase-A missions
R&D costs have been funded
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

13. DPF status (2) DPF status
JAXA is planning to launch 3 small satellite by the year 2013
using next-generation solid rocket booster under development
Reduce time and cost by means of ‘Standard bus system’
Preliminary parameters
Bus weight : ~ 200kg, Bus power : ~ 900W
　 Downlink ~ 4Mbps, Data storage ~ 1GByte
3-axes angular control
1st mission (2011) has been decided to be
TOPS (Space telescope mission for planet observation)
2nd and 3rd mission will be selected by 2009 March
Candidate missions
DPF: GW observation
DIOS: X-ray telescope for dark baryon investigation
ERG: Plasma and particle detector for geo-space investigation
Satellite for Magnet-plasma sail technology demonstration, …
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

14. DPF status (3) R&D plan for DPF
(Under discussion)
Required to submit Phase-A proposal by 2009 March
R&D for core technologies
Laser frequency stabilization
Mirror and its housing (local sensor, actuator, launch-lock system)
Micro thruster
Drag-free control simulation
Detailed design and noise investigation
Target: launch in 2012 or 2013 as
2nd or 3rd standard small satellite of JAXA
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

15. Summary DECIGO pathfinder: First demonstration satellite for DECIGO
　　One small satellite
(Weight: ~ kg, Orbit: around the earth)
10cm Fabry-Perot cavity formed by free masses
Stabilized laser source
Drag-free control system
Local Sensor
Test and demonstration for DECIGO
Gravitational-wave observation
0.1Hz-1Hz band
BH QNM and Mid.-BH inspiral at Galactic center
Actuator
Selected and funded as one of the
candidates of JAXA’s small satellite missions
Hoping to be launched in
Thruster
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

16. Topics Steps for DPF Small module to be launched in 2008
Small test-mass module
Small module to be launched in 2008
Photo sensor
Test mass
SDS-I :
Small (~100kg) satellite
for demonstration of space technologies
To be launched in 2008 summer by H-IIA
as piggy-back satellite of GOSAT
SWIMmn:
very small GW detector module will be included
in SWIM (SpaceWire Interface demonstration Module)
Coil-magnet actuator
Free-falling experiment using balloon
BOV 2.5 :
Free-falling vehicle from large balloon
~30 sec free-falling streach from 40km altitude
Drag-free control system using gas-jet thrusters
Prototype of SWIMmn is included in BOV
Experiment module
Diameter ~ 28cm
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

17. 　　　　 　End
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )