lisa pathfinder - csic on board lisa pathfinder • the lisa technology package (ltp) • european...
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LISA Pathfindermeasuring pico-meters and femto-Newtons in space
M Hewitson for the LPF teamBarcelona, February 15th 2012
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Observing from Space
2Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Observing from Space
2Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Observing from Space
• Push down to much lower frequencies: mHz
2Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Observing from Space
• Push down to much lower frequencies: mHz
• Stability of ground-based instruments is difficult to achieve at these frequencies• seismic wall ~10 Hz
2Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Observing from Space
• Push down to much lower frequencies: mHz
• Stability of ground-based instruments is difficult to achieve at these frequencies• seismic wall ~10 Hz
2Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Observing from Space
• Push down to much lower frequencies: mHz
• Stability of ground-based instruments is difficult to achieve at these frequencies• seismic wall ~10 Hz
• Going to space:• Increase arm-length (increase sensitivity, ∆L/L )
2Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Observing from Space
• Push down to much lower frequencies: mHz
• Stability of ground-based instruments is difficult to achieve at these frequencies• seismic wall ~10 Hz
• Going to space:• Increase arm-length (increase sensitivity, ∆L/L ) • Quite environment (reduce noise)
2Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
LISA concept
3Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
LISA concept
3
SC
Telescope
OB
OB
PM
PM
GRS
GRS
Thruster
Thruster
Thruster
Thruster
Thruster
Thruster Telescope
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
LISA concept
3
SC
Telescope
OB
OB
PM
PM
GRS
GRS
Thruster
Thruster
Thruster
Thruster
Thruster
Thruster Telescope
GRAVITATIONAL REFERENCE SENSOR (GRS) Test Mass + Drag free
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
LISA concept
3
SC
Telescope
OB
OB
PM
PM
GRS
GRS
Thruster
Thruster
Thruster
Thruster
Thruster
Thruster Telescope
GRAVITATIONAL REFERENCE SENSOR (GRS) Test Mass + Drag free
OPTICAL METROLOGY Optical Bench (OB) + Phasemeter (PM)
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
LISA concept
3
SC
Telescope
OB
OB
PM
PM
GRS
GRS
Thruster
Thruster
Thruster
Thruster
Thruster
Thruster Telescope
GRAVITATIONAL REFERENCE SENSOR (GRS) Test Mass + Drag free
OPTICAL METROLOGY Optical Bench (OB) + Phasemeter (PM)
THRUSTER
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
LISA Measurement -> LISA Pathfinder
4Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
LISA Measurement -> LISA Pathfinder
4
a longway
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
LISA Measurement -> LISA Pathfinder
4
a longway
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
The LISA Pathfinder Mission
• Technology demonstrator for a LISA-like mission:• Local interferometry• micro-Newton propulsion• Gravitational Reference Sensor• Drag-free control
• LPF will be placed in orbit around L1• Requirements relaxed
• 1 order of magnitude in differential acceleration• LPF req. 3x10-14 m/s2 @ 1mHz
• 1 order of magnitude higher frequency• LPF meas. bandwidth 1mHz < f < 30mHz
5Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
The LISA Pathfinder Mission
• Technology demonstrator for a LISA-like mission:• Local interferometry• micro-Newton propulsion• Gravitational Reference Sensor• Drag-free control
• LPF will be placed in orbit around L1• Requirements relaxed
• 1 order of magnitude in differential acceleration• LPF req. 3x10-14 m/s2 @ 1mHz
• 1 order of magnitude higher frequency• LPF meas. bandwidth 1mHz < f < 30mHz
5Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
The LISA Pathfinder Team
6
Netherlands: - ISS SCOE
Germany: - Co-Principle Investigator - LTP Architect (Astrium)- Laser
Switzerland:- ISS Front End Electronics
Italy: - Principle Investigator - Inertial Sensor- Caging Mechanism
United Kingdom: - Optical Bench- Phase-meter - Charge Management
France:- Laser modulator
Spain: - Data Diagnostics System- Data Management Unit
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Payloads on board LISA Pathfinder
• The LISA Technology Package (LTP)• European payload• Full system
• thrusters, test-masses, inertial sensor, interferometers, etc
• The Disturbance Reduction System (DRS)• NASA payload• Alternative thrusters• Alternative drag-free control
7Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Payloads on board LISA Pathfinder
• The LISA Technology Package (LTP)• European payload• Full system
• thrusters, test-masses, inertial sensor, interferometers, etc
• The Disturbance Reduction System (DRS)• NASA payload• Alternative thrusters• Alternative drag-free control
7Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
The LISA Technology Package (LTP)
8Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
x-axis measurement
9Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
IFO X1: SC-TM1 measurement
10Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Drag-free on TM1
11Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
IFO X12: TM1-TM2 displacement
12Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Suspension control
13Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Spacecraft
14Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Spacecraft
14Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Spacecraft
14Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
.
15Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
The LTP
16Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
The LTP
16
Reference Laser Unit
Data Management Unit
Phasemeter
Optical Bench
Vacuum EnclosureInertial Sensor
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012 17Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Current status (what’s missing?)
18Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Current status (what’s missing?)• Micro-propulsion system
• problems with Ca FEEPs in the past• may now be solved
• ESA have been looking at alternative systems• modified Ca FEEPs, Indium FEEPS, Cold gas,
mini-RIT, Colloid• further testing to be done before deciding on a
solution
18Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Current status (what’s missing?)• Micro-propulsion system
• problems with Ca FEEPs in the past• may now be solved
• ESA have been looking at alternative systems• modified Ca FEEPs, Indium FEEPS, Cold gas,
mini-RIT, Colloid• further testing to be done before deciding on a
solution
• Caging mechanism• Construction of original launch-lock proved
challenging• ESA investigating alternatives
• New cam-based system, single-shot mechanism• single-shot mechanism has been selected
18Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Testing: On-station Thermal Tests
• Uses a thermal-optical qualification model in place of the flight LTP• Consists of a flight optical bench, with flight mounting
struts, and thermal mass dummies of the inertial sensors
19Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Testing: On-station Thermal Tests
• Uses a thermal-optical qualification model in place of the flight LTP• Consists of a flight optical bench, with flight mounting
struts, and thermal mass dummies of the inertial sensors
19
Alberto Lobo’s talk
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Science Goals
20Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Science Goals
• Obtain the best geodesic motion possible• quietest differential acceleration of the two TMs
• 3 x 10-14 m s-2 /√Hz at 1 mHz• pm accuracy position measurement of TM-SC, TM-TM
• commissioning by changing system parameters• determine best configuration by experiments
20Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Science Goals
• Obtain the best geodesic motion possible• quietest differential acceleration of the two TMs
• 3 x 10-14 m s-2 /√Hz at 1 mHz• pm accuracy position measurement of TM-SC, TM-TM
• commissioning by changing system parameters• determine best configuration by experiments
• Develop a noise model of the system• allows the projection of the performance of
technologies to LISA
20Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Science Goals
• Obtain the best geodesic motion possible• quietest differential acceleration of the two TMs
• 3 x 10-14 m s-2 /√Hz at 1 mHz• pm accuracy position measurement of TM-SC, TM-TM
• commissioning by changing system parameters• determine best configuration by experiments
• Develop a noise model of the system• allows the projection of the performance of
technologies to LISA
20Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Mission Operations
• We have 90 days to achieve the goals• characterise and optimise the system
• All days are filled with pre-planned experiments• some flexibility is built-in
• Data analysis of the experiments will be done in real-time
21Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Mission Operations
• We have 90 days to achieve the goals• characterise and optimise the system
• All days are filled with pre-planned experiments• some flexibility is built-in
• Data analysis of the experiments will be done in real-time
21Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Experiments
22
• Technical studies are broken down into investigations
• These investigations are then packed into the time-line
Measurement of Parasitic Voltages
Measurement of differential acceleration noise on LISA Pathfinder
Measurement of cross-talk between the y-axis and the x-axis on the LTP
Measurement of LTP dynamical coefficients by system identification
Analysis of Data from the Radiation Monitor on LISA Pathfinder
Thermal experiments on board the LTP
Magnetic experiments on board the LTP
OPD noise investigations for LTP
Laser frequency noise characterisation for LTP
Laser Amplitude Noise Characterisation for LTP
The Drift Mode for LISA Pathfinder
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Estimating residual differential TM acceleration (1)
• The direct observables of the instrument are displacements
• We need to estimate residual forces acting on the TMs
• We can:• estimate acceleration of the SC
• derived from SC-TM1 displacement• estimate differential acceleration of two TMs
• derived from differential displacement of two TMs
23Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Estimating residual differential TM acceleration (2)
24
�DS�1 �C
⇥⇤o = ⇤A + DS�1⇤on
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Estimating residual differential TM acceleration (2)
24
�DS�1 �C
⇥⇤o = ⇤A + DS�1⇤on
observationnoise
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Estimating residual differential TM acceleration (2)
24
�DS�1 �C
⇥⇤o = ⇤A + DS�1⇤on
observationnoiseresidual
acceleration
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Estimating residual differential TM acceleration (2)
24
�DS�1 �C
⇥⇤o = ⇤A + DS�1⇤on
observationnoiseresidual
acceleration
measurement
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Estimating residual differential TM acceleration (2)
24
�DS�1 �C
⇥⇤o = ⇤A + DS�1⇤on
observationnoiseresidual
acceleration
measurement
system
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Estimating residual differential TM acceleration (2)
24
�DS�1 �C
⇥⇤o = ⇤A + DS�1⇤on
⇥A
⇥on
⇥o
S
C
D�1
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Estimating residual differential TM acceleration (2)
24
�DS�1 �C
⇥⇤o = ⇤A + DS�1⇤on
⇥A
⇥on
⇥o
S
C
D�1
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Estimating residual differential TM acceleration (2)
24
�DS�1 �C
⇥⇤o = ⇤A + DS�1⇤on
⇥A
⇥on
⇥o
S
C
D�1
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Parameter estimation
• Employ different estimation methods to work with multiple inputs, multiple outputs
• All methods require a parametric model of the system
25Wednesday, February 15, 12
0 0.5 1 1.5 2 2.5 3x 104
−6
−5
−4
−3
−2
−1
0
1
2
3
4 x 10−9 Time origin: 2010−04−23 07:36:36.000 UTC
Am
plitu
de [
m]
Time [s]
LinearNonlinearMCMC
M Hewitson, LPF, Barcelona, 15th Feb 2012
Parameter estimation
26
0 0.5 1 1.5 2 2.5 3x 104
−5
−4
−3
−2
−1
0
1
2
3 x 10−8 Time origin: 2010−04−23 07:36:36.000 UTC
Am
plitu
de [
m]
Time [s]
LinearNonlinearMCMCData
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0 0.5 1 1.5 2 2.5 3x 104
−6
−5
−4
−3
−2
−1
0
1
2
3
4 x 10−9 Time origin: 2010−04−23 07:36:36.000 UTC
Am
plitu
de [
m]
Time [s]
LinearNonlinearMCMC
M Hewitson, LPF, Barcelona, 15th Feb 2012
Parameter estimation
26
0 0.5 1 1.5 2 2.5 3x 104
−5
−4
−3
−2
−1
0
1
2
3 x 10−8 Time origin: 2010−04−23 07:36:36.000 UTC
Am
plitu
de [
m]
Time [s]
LinearNonlinearMCMCData
10−4 10−3 10−2 10−1 10010−12
10−11
10−10
10−9
10−8
10−7
Spec
tral
den
sity
[m
Hz−
1/2 ]
Frequency [Hz]
LinearNonlinearMCMCNoise o_12
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Results using mission simulator
• We can simulate experiments using the mission simulator• 3D, non-linear, time-domain simulation
• We can recover the parameters with high precision• very dependent on having a good model
27Wednesday, February 15, 12
M Hewitson, LPF, Sheffield, 13th September 2011 28
Data Analysis
Wednesday, February 15, 12
M Hewitson, LPF, Sheffield, 13th September 2011 28
Data Analysis
•DA Software• Toolbox of algorithms to act on the data• Repository for storing data products• Client for submitting and retrieving to/from repository• Documentation and testing
Wednesday, February 15, 12
M Hewitson, LPF, Sheffield, 13th September 2011 28
Data Analysis
•DA Software• Toolbox of algorithms to act on the data• Repository for storing data products• Client for submitting and retrieving to/from repository• Documentation and testing
•DA Activities• Simulate experiments• Design, build and test analyses and associated tools• Train scientists
Wednesday, February 15, 12
M Hewitson, LPF, Sheffield, 13th September 2011 28
Data Analysis
•DA Software• Toolbox of algorithms to act on the data• Repository for storing data products• Client for submitting and retrieving to/from repository• Documentation and testing
•DA Activities• Simulate experiments• Design, build and test analyses and associated tools• Train scientists
LTPDAhttp://www.lisa.aei-hannover.de/ltpda/
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Noise budget
• Various noise contributions can be directly measured
• Some noise couplings must be modelled• using estimates of physical parameters together with
a system model• Some noise contributions must be estimated/
modelled from design
29Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Requirements Differential Force Noise Budget
30Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Free-flight experiment
31Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Free-flight experiment
• Capacitive actuation will be close to limiting around 1mHz
31Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Free-flight experiment
• Capacitive actuation will be close to limiting around 1mHz
• Do an experiment with the actuation off• must be short otherwise the TM will drift too far• repeat many times
31Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Free-flight experiment
• Capacitive actuation will be close to limiting around 1mHz
• Do an experiment with the actuation off• must be short otherwise the TM will drift too far• repeat many times
• Experiment:• kick test-mass away• turn off actuation• let the test-mass drift (in parabola)• repeat
31Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Simulation
32Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
PSD Estimate
33
Simulation with requirement-level noises but x3 reduced direct TM
force noise
Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Towards s/LISA/%s
34Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012
Conclusion• LPF is well on its way!
• Most of the hardware is there• awaiting thrusters and
launch lock• Most of the
experiments are already defined• many are even tested
with DA in place• We have a clear path
to launch• Launch in 2014
35Wednesday, February 15, 12
M Hewitson, LPF, Barcelona, 15th Feb 2012 36
Thank you
Wednesday, February 15, 12