LISA Gravitational Reference Sensors - .for GRS Gap Measurement Optical Fiber Detector Reference

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Transcript of LISA Gravitational Reference Sensors - .for GRS Gap Measurement Optical Fiber Detector Reference

  • TeV Particle Astrophysics II, Madison, WI 8/20061

    GRSLISA_GRS_060830.pptLISALISA

    LISA Gravitational Reference Sensors

    TeV Particle Astrophysics IIUniversity of Wisconsin, Madison, August 28-31, 2006

    Ke-Xun SunStanford University

    For the LISA GRS Research Community

  • TeV Particle Astrophysics II, Madison, WI 8/20062

    GRSLISA_GRS_060830.pptLISALISA

    LISA: A Spacecraft Constellation

    Each spacecraft houses two Gravitational Reference Sensors (GRS)

    LISA has 6 GRS

  • TeV Particle Astrophysics II, Madison, WI 8/20063

    GRSLISA_GRS_060830.pptLISALISA

    GRS

    Gravitational Reference Sensor (GRS) in the LISA Spacecraft

    GRS is one of the core scientificinstruments the heart of LISA

  • TeV Particle Astrophysics II, Madison, WI 8/20064

    GRSLISA_GRS_060830.pptLISALISA

    LTP, LISA and BBO Configurations and Performance

    Space Fleet LTP/ST-7 LISA BBO

    Configuration

    IMS/DRS test

    1

    20 cm

    20 mW

    N.A.

    10-14 ms-2Hz-

    Observational Goal Discrete Sources

    Gravitational Wave Relics

    # of S/Cs 3 12

    Arm Length 5x106 km 5x104 km

    Laser Power 2 W 300 W

    Strain Sensitivity h~10

    -21 h~10-23

    Acceleration Limit 10

    -15 ms-2Hz- 10-17 ms-2Hz-

  • TeV Particle Astrophysics II, Madison, WI 8/20065

    GRSLISA_GRS_060830.pptLISALISA

    LISA Baseline Performance

  • TeV Particle Astrophysics II, Madison, WI 8/20066

    GRSLISA_GRS_060830.pptLISALISA

    LISA Mid and Low Frequency RangeSensitivity Determined by GRS Performance

    GRS

    }IMS

  • TeV Particle Astrophysics II, Madison, WI 8/20067

    GRSLISA_GRS_060830.pptLISALISA

    GRS consists of: A freely-floating proof mass within a

    housing, Position measurement of the test mass

    w.r.t. housing Control of test mass orientation Charge control subsystem

    Disturbance reduction from: Solar magnetic field Solar radiation pressure Residual gas pressure Thermal radiation pressure Charging by cosmic rays Spacecraft self-gravity Spacecraft magnetic fields Spacecraft electric fields

    LTP Gravitational Reference Sensor

    LTP Graphics thanks to Stefan Vitale

  • TeV Particle Astrophysics II, Madison, WI 8/20068

    GRSLISA_GRS_060830.pptLISALISA

    LTP Engineering Model Testing

  • TeV Particle Astrophysics II, Madison, WI 8/20069

    GRSLISA_GRS_060830.pptLISALISA

    LTP GRS Testing

    LTP Graphics thanks to Stefan Vitale

  • TeV Particle Astrophysics II, Madison, WI 8/200610

    GRSLISA_GRS_060830.pptLISALISA

    Stanford Gravity Probe-B and Previous Flight GP-B was launched April 2004

    and started science measurement in August

    GP-B has experimentally measured frame-dragging effects

    GP-B experiences are an important assets to LISA-BBO R&D

    GRS based on Stanford experience with

    TRIAD (Stanford/APL, 1972, < 5x10-11 m/s2 RMS over 3 days)

    GP-B (Stanford, launch 2002, < 2x10-12 m.s-2/Hz at 5x10-3 Hz )

    Position sensing, charge control from GP-B

    GP-B: 17 DOF GP-B is a critical development

    for high precision space flight, including LISA

    Drag-free technology Cryogenics Precision fabrication Caging Charge management

  • TeV Particle Astrophysics II, Madison, WI 8/200611

    GRSLISA_GRS_060830.pptLISALISA

    ST-7 Development at Stanford

    Au/Pt PM

    Housing with compound material

    Vacuum system

    Electronics and system integration

  • TeV Particle Astrophysics II, Madison, WI 8/200612

    GRSLISA_GRS_060830.pptLISALISA

    LISA Noise Sources

    Additional leading term: Voltage Reference Instability

  • TeV Particle Astrophysics II, Madison, WI 8/200613

    GRSLISA_GRS_060830.pptLISALISA

    Cross Talk is the Leading Noise SourceAnyway to Reduce?

    Cross talk due to : 1) Proof mass shape2) Two proof masses

  • TeV Particle Astrophysics II, Madison, WI 8/200614

    GRSLISA_GRS_060830.pptLISALISA

    Each Spacecraft has Two Cubic Proof Masses

    Proof Mass

    ProofMass

    To and from Remote Spacecraft

    Waveplate

    Transmissive optics

    Sensitive path

    Great elaborated structure, but Interlinked scheme for re-correlation Long sensitive path Coupling throughout the system dn/dT problem in transmissive optics

    Alignment coupling

  • TeV Particle Astrophysics II, Madison, WI 8/200615

    GRSLISA_GRS_060830.pptLISALISA

    Modular GRS has Only One Proof MassReduced Cross Talk

    Modular GRS: The New LISA Baseline Architecture

    LISA 5 (2004)

    Amaldi 6 (2005)

  • TeV Particle Astrophysics II, Madison, WI 8/200616

    GRSLISA_GRS_060830.pptLISALISA

    A Standalone GRS Architecture Presented at LISA 5th Symposium

    OutgoingLaser Beam

    Proof Mass

    Large gap

    GRS Housing

    Optical ReadoutBeam

    Telescope

    Incoming Laser Beam

    Details Shown in Figure 2

    Single proof mass Modularized, stand-alone GRS GW detection optics external to

    GRS External laser beam not directly

    shining on test mass (Just learned that LISA will follow! -- Heinzel talk before ours in this session)

    Internal optical sensing for higher precision

    Large gap for better disturbance reduction

    True 3-dim drag-free architecture

    Determine the geometric center and center of mass

    Sun, Allen, Buchman, DeBra, Byer, CQG (22) 2005 S287-S296

  • TeV Particle Astrophysics II, Madison, WI 8/200617

    GRSLISA_GRS_060830.pptLISALISA

    An All-Reflective Configuration for Modular GRS

    (b) (c) (d) (e)

    Housing Wall

    Thin, Double-sided, Dual Gratings

    Laser for External Interferometer

    Optical Fiber

    To and from Remote Spacecraft

    Optical source for GRS Gap Measurement

    Optical Fiber

    Detector

    Reference Relay Region

    1~2 cm gap(sensitive optical path)

    Spherical PM.Diameter 2~10 cm

    (a)

    Detector

  • TeV Particle Astrophysics II, Madison, WI 8/200618

    GRSLISA_GRS_060830.pptLISALISA

    Diffractive Optics Simplifiesfor LISA Baseline with Cubic Proof Mass

    Compact construction Displacement + Angular sensing

    The only sensitive optical path

    SEM Image of Grating

    Grating fabrication studies- Funded by JPL DRDF- The progress is ahead of schedule- e-beam lithography at Stanford

    Nano-Science Facility- Grating pattern on dielectric

    demonstrated- Grating on noble metal in progress

  • TeV Particle Astrophysics II, Madison, WI 8/200619

    GRSLISA_GRS_060830.pptLISALISA

    Multi-mirror design

    Telescope main heavy primary mirror and tube fixed

    Steering direction by moving (rotating) lighter tertiary and quaternary mirrors

    Assign coarse and fine adjustments to different mirrors

    Add CCD imager for seeking acquisition

    CCD imager

    Webb Space Telescope Multi-Mirror Steering Scheme

    From interferometer laserto remote S/C

    From remote S/C

  • TeV Particle Astrophysics II, Madison, WI 8/200620

    GRSLISA_GRS_060830.pptLISALISA

    The Single Proof Mass GRS ArchitectureIt is now adopted by BBO

    Presented at BBO Working Group Meeting, Collocated with LISA 5thSymposium, ESTEC, Netherlands, July 2004

    BBO new design as of December 2004, presented by JPL at Texas Symposium at Stanford

  • TeV Particle Astrophysics II, Madison, WI 8/200621

    GRSLISA_GRS_060830.pptLISALISA

    Strap Down (Modular GRS) Has Become the New LISA Interferometer Baseline

  • TeV Particle Astrophysics II, Madison, WI 8/200622

    GRSLISA_GRS_060830.pptLISALISA

    Comparison of Control ComplexityStand-alone GRS Simplifies Control

    Mission & DOF Counts

    GPB ST-7 LISA BBO(New)

    Stand-alone GRS LISA/BBO

    Displacement DOF

    6

    Angular DOF

    Other DOF

    Total DOF 19 13 10

    Single S/C Decoupled DOF counts 3+7

    Time to setup experiment

    3 mo. Mission 3 mo.

    12 mo. (?)

    ? Shorter than coupled scheme

    120(New BBO)

    3

    1

    Total Fleet DOF 17 18 57 156 30 (LISA)

    15 9 9 6

    2 9 9 6

    1 1Single SC

  • TeV Particle Astrophysics II, Madison, WI 8/200623

    GRSLISA_GRS_060830.pptLISALISA

    An Alternative Also Considered by LISA

    LISA perceived a similar approach

    Single proof mass Fiduciary mirror based beam

    steering Simpler than half/half

    separation scheme

    System and Technology Report, July 2000,A.4.4, P270, Laser Metrology Harness

  • TeV Particle Astrophysics II, Madison, WI 8/200624

    GRSLISA_GRS_060830.pptLISALISA

    Baseline Spacecraft Structure Before Modular GRS

    Graphics thanks to Ulrich Johann

  • TeV Particle Astrophysics II, Madison, WI 8/200625

    GRSLISA_GRS_060830.pptLISALISA

    New Proposed Structure after Strap-Down (Modular GRS)

    Graphics thanks to Ulrich Johann, EDS Astrium

  • TeV Particle Astrophysics II, Madison, WI 8/200626

    GRSLISA_GRS_060830.pptLISALISA

    Structure Using Single Proof Mass

    Cleaner structure

    Smaller volume

    Smaller rocket

    Graphics thanks to Ulrich Johann

  • TeV Particle Astrophysics II, Madison, WI 8/200627

    GRSLISA_GRS_060830.pptLISALISA

    Developing Modular GRS

    Thermal control

    Center of Mass Measurement

    Mass distributionMoment of Inertia measurement

    Optical displacement sensing

    Grating design and fabrication

    External Interferometry

    UV LED charge management system

    Electromagnetic modeling

    Surface studies

    Grating angular sensor