Lisa Pathfinder: NASA Advisory Council Astrophysics Subcommittee ...
Ira Thorpe, NASA/GSFC On behalf of the LPF Team NASA Advisory Council Astrophysics Subcommittee Meeting Washington, DC March 16th, 2016
1
Why LISA Pathfinder?
2
10
-12
= 0.000000000001
Picophobia (paıkoƱ-fōbēǝ) 1. (noun) Extreme or irrational fear of large negative exponents, especially when related to engineering requirements. (origins: Spanish, Greek) How many mils is a picometer?
3
Picophobia for LISA
I. Thorpe
•
Acceleration noise: ~3x10-15 m/s2/Hz1/2 @ 1mHz
•
Distance measurement: ~7x10-12 m/Hz1/2 @ 1mHz
•
received light power: ~10-10 W
•
temperature stability: ~10-6 K/Hz1/2 @ 1mHz
•
pointing requirement: ~8x10-9 rad/Hz1/2 @ 1mHz
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
4
Solution: Fly a Tech Demo Textbook GW detector Measure curvature by timing photon travel between freely-falling objects
LISA-like mission freely-falling objects → drag-free test masses photon timing → heterodyne interferometry multiple arms → noise rejection, improved signal
Technology Demonstrator Single LISA arm reduced to fit on one spacecraft GW signal vanishes Instrument Noise remains I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
5
LPF Goals
Sa1/2 (f )
relative acceleration noise
10
r
10
3 ⇥ 10
14
f m 4 p ) 1+( 3 mHz s2 Hz
GRACE
−10
−11
GOCE Microscope
−12
10
relative displacement measurement noise
Sx1/2 (f )
9.1 ⇥ 10
12
s
3 mHz 4 m ) p 1+( f Hz
−13
10
LPF Requirement LPF Current Best Estimate*
−14
10
NGO Requirement LISA
−15
10
−4
10
−3
10
−2
10
−1
10
*Pre-flight estimate based on component testing and modeling
I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
6
Key Components •
•
•
I. Thorpe
Spacecraft (ESA) •
Micronewton thrusters (cold gas)
•
Drag-free control laws
•
Emphasis on mechanical, thermal, & gravitational stability
LISA Technology Package (ESA & European Consortium) •
Two gravitational reference sensors
•
Optical Metrology System
•
Thermal/Magnetic Diagnostic System
ST7-DRS (NASA/JPL) •
Micronewton thrusters (colloidal)
•
Drag-free control laws (use LTP sensors/actuators)
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
7
Operations Launch
•
•
Industrial Commissioning, LTP Operations, ST7 Operations, Extended Mission?
IOCR
Launch, LEOP, Transfer, Separation, De-spin
Commissioning
LTP Science Ops
DRS Commissioning
DRS Operations
60 days
14 days
3 months
10 days
3 months
Day 1 H1 H2 H3 H4 H5
Goal: physics-based model for the residual acceleration noise
Day 2
Day 3
Day 4
Discharge
Noise Run
Discharge
Noise Run
Working Point
Stray Potentials
Sys ID
3
ns Se ion sit Po
1
0
10 -4 10
I. Thorpe
Total
Direct Forces
Electrostatic Suspension
te
rs
10
2
us
Star r e Track
Data analysis must be rapid & accurate to optimize planning for the remaining mission timeline
10
gle g An nsin Se
•
Operations are a series of experiments to measure various couplings/noise contributions/etc.
Th r
•
ing
M Hewitson, LISA Symposium X, Gainesville, May 20th 2014
10
-3
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
10
-2
10
-1
8
Schedule of Events (nominal) Dec 7-11: Apogee-raising burns Dec 12: Trajectory trim Dec 17-20: Cold Gas Thruster Commissioning Jan. 2-10: CMNT Commissioning Jan. 11: LTP Commissioning Begins Jan 22: Propulsion module separation Feb 3: Test Mass De-cage (launch lock) Feb 15/16: Test Mass release (electrostatic control) Feb 29: LTP Commissioning Ends Mar. 7th: In-Orbit Commissioning Review Passed Mar-June: LTP Operations Late June: DRS Commissioning June-Sept: DRS Operations Extended Mission / Joint Operations ? I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
9
I&T and Launch Campaign Highlights
10
11
12
13
14
15
2015-12-03 01:04:00 — Kourou, French Guiana
I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
16
Current Status LTP Science Operations Week 3 Philosophy take it slow understand system gradually introduce more aggressive experiments
LTP Science Team Members working at ESOC in Darmstadt, Germany !
Hope to release intermediate results at some point during LTP operations
Total
ect F
orc
es
Electrostatic Actuation
Trac
1 0
ker
Acceleration Noise
Dir
Star
I. Thorpe
10
OM SS en
Requirements
Keep up-to-date
sin
g
100
Thrusters
1
10
Fourier Frequency [mHz]
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
100
17
Backup
18
History of LPF 1998: ELITE (European LIsa TEchnology) proposed Homodyne interferometer Launch date 2002 2000: ELITE proposed as SMART-2 (Small Missions for Advanced Research in Technology) Two spacecraft, three payloads (NASA)
2001: SMART-2 Descoped and re-named LISA Pathfinder
single spacecraft, two payloads LISA Technology Package (Europe) and DRS (NASA)
2005: DRS Descoped DRS interferometer and inertial sensor removed DRS control laws and thrusters will use LTP sensors
I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
19
Drag Free Control
TM TM ç SC SC SC and TMexternal in free fall SC experiences disturbance
I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
20
Mission Design
I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
21
Gravitational Reference Sensor Test mass: 46mm cube of Au-Pt alloy (2 kg) surrounded by electrode housing with 3-4mm gaps electrodes used to sense position/ attitude and apply forces/torques
uncoated TM
electrode housing
Non-contact charge control via UV lamps Housed in titanium vacuum vessel Caged during launch, released to electrostatic suspension on orbit integrated electrode housings I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
vacuum can 22
Optical Metrology System •
Four separate Mach-Zehnder interferometers to measure positions and angles
•
Hydroxy-catalysis bonding to maintain alignment & provide dimensional stability 4
I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
23
Micropropulsion Systems
•
Maximum thrust ~ 30µN
•
Thrust precision ~ 0.1µN
Colloidal MicroNewton Thruster (JPL/BUSEK) I. Thorpe
Cold Gas Microthruster (used on GAIA)
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
24
Platform for Precision Measurement
I. Thorpe
•
2.3 m x 1.0 m
•
422kg
•
magnetically clean
•
precision gravitational balance
•
thermally clean
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
25
1
Why LISA Pathfinder?
2
10
-12
= 0.000000000001
Picophobia (paıkoƱ-fōbēǝ) 1. (noun) Extreme or irrational fear of large negative exponents, especially when related to engineering requirements. (origins: Spanish, Greek) How many mils is a picometer?
3
Picophobia for LISA
I. Thorpe
•
Acceleration noise: ~3x10-15 m/s2/Hz1/2 @ 1mHz
•
Distance measurement: ~7x10-12 m/Hz1/2 @ 1mHz
•
received light power: ~10-10 W
•
temperature stability: ~10-6 K/Hz1/2 @ 1mHz
•
pointing requirement: ~8x10-9 rad/Hz1/2 @ 1mHz
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
4
Solution: Fly a Tech Demo Textbook GW detector Measure curvature by timing photon travel between freely-falling objects
LISA-like mission freely-falling objects → drag-free test masses photon timing → heterodyne interferometry multiple arms → noise rejection, improved signal
Technology Demonstrator Single LISA arm reduced to fit on one spacecraft GW signal vanishes Instrument Noise remains I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
5
LPF Goals
Sa1/2 (f )
relative acceleration noise
10
r
10
3 ⇥ 10
14
f m 4 p ) 1+( 3 mHz s2 Hz
GRACE
−10
−11
GOCE Microscope
−12
10
relative displacement measurement noise
Sx1/2 (f )
9.1 ⇥ 10
12
s
3 mHz 4 m ) p 1+( f Hz
−13
10
LPF Requirement LPF Current Best Estimate*
−14
10
NGO Requirement LISA
−15
10
−4
10
−3
10
−2
10
−1
10
*Pre-flight estimate based on component testing and modeling
I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
6
Key Components •
•
•
I. Thorpe
Spacecraft (ESA) •
Micronewton thrusters (cold gas)
•
Drag-free control laws
•
Emphasis on mechanical, thermal, & gravitational stability
LISA Technology Package (ESA & European Consortium) •
Two gravitational reference sensors
•
Optical Metrology System
•
Thermal/Magnetic Diagnostic System
ST7-DRS (NASA/JPL) •
Micronewton thrusters (colloidal)
•
Drag-free control laws (use LTP sensors/actuators)
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
7
Operations Launch
•
•
Industrial Commissioning, LTP Operations, ST7 Operations, Extended Mission?
IOCR
Launch, LEOP, Transfer, Separation, De-spin
Commissioning
LTP Science Ops
DRS Commissioning
DRS Operations
60 days
14 days
3 months
10 days
3 months
Day 1 H1 H2 H3 H4 H5
Goal: physics-based model for the residual acceleration noise
Day 2
Day 3
Day 4
Discharge
Noise Run
Discharge
Noise Run
Working Point
Stray Potentials
Sys ID
3
ns Se ion sit Po
1
0
10 -4 10
I. Thorpe
Total
Direct Forces
Electrostatic Suspension
te
rs
10
2
us
Star r e Track
Data analysis must be rapid & accurate to optimize planning for the remaining mission timeline
10
gle g An nsin Se
•
Operations are a series of experiments to measure various couplings/noise contributions/etc.
Th r
•
ing
M Hewitson, LISA Symposium X, Gainesville, May 20th 2014
10
-3
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
10
-2
10
-1
8
Schedule of Events (nominal) Dec 7-11: Apogee-raising burns Dec 12: Trajectory trim Dec 17-20: Cold Gas Thruster Commissioning Jan. 2-10: CMNT Commissioning Jan. 11: LTP Commissioning Begins Jan 22: Propulsion module separation Feb 3: Test Mass De-cage (launch lock) Feb 15/16: Test Mass release (electrostatic control) Feb 29: LTP Commissioning Ends Mar. 7th: In-Orbit Commissioning Review Passed Mar-June: LTP Operations Late June: DRS Commissioning June-Sept: DRS Operations Extended Mission / Joint Operations ? I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
9
I&T and Launch Campaign Highlights
10
11
12
13
14
15
2015-12-03 01:04:00 — Kourou, French Guiana
I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
16
Current Status LTP Science Operations Week 3 Philosophy take it slow understand system gradually introduce more aggressive experiments
LTP Science Team Members working at ESOC in Darmstadt, Germany !
Hope to release intermediate results at some point during LTP operations
Total
ect F
orc
es
Electrostatic Actuation
Trac
1 0
ker
Acceleration Noise
Dir
Star
I. Thorpe
10
OM SS en
Requirements
Keep up-to-date
sin
g
100
Thrusters
1
10
Fourier Frequency [mHz]
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
100
17
Backup
18
History of LPF 1998: ELITE (European LIsa TEchnology) proposed Homodyne interferometer Launch date 2002 2000: ELITE proposed as SMART-2 (Small Missions for Advanced Research in Technology) Two spacecraft, three payloads (NASA)
2001: SMART-2 Descoped and re-named LISA Pathfinder
single spacecraft, two payloads LISA Technology Package (Europe) and DRS (NASA)
2005: DRS Descoped DRS interferometer and inertial sensor removed DRS control laws and thrusters will use LTP sensors
I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
19
Drag Free Control
TM TM ç SC SC SC and TMexternal in free fall SC experiences disturbance
I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
20
Mission Design
I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
21
Gravitational Reference Sensor Test mass: 46mm cube of Au-Pt alloy (2 kg) surrounded by electrode housing with 3-4mm gaps electrodes used to sense position/ attitude and apply forces/torques
uncoated TM
electrode housing
Non-contact charge control via UV lamps Housed in titanium vacuum vessel Caged during launch, released to electrostatic suspension on orbit integrated electrode housings I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
vacuum can 22
Optical Metrology System •
Four separate Mach-Zehnder interferometers to measure positions and angles
•
Hydroxy-catalysis bonding to maintain alignment & provide dimensional stability 4
I. Thorpe
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
23
Micropropulsion Systems
•
Maximum thrust ~ 30µN
•
Thrust precision ~ 0.1µN
Colloidal MicroNewton Thruster (JPL/BUSEK) I. Thorpe
Cold Gas Microthruster (used on GAIA)
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
24
Platform for Precision Measurement
I. Thorpe
•
2.3 m x 1.0 m
•
422kg
•
magnetically clean
•
precision gravitational balance
•
thermally clean
NASA Advisory Council Astrophysics Subcommittee Meeting - March 16th, 2016 - Washington, DC
25
