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LISA Pathfinder

LISA Pathfinder

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LISA Pathfinder

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  1. Third International ASTROD Symposium, Beijing 14 July 2006 LISA Pathfinder A Technology Demonstrator for the LISA Space Gravitational-Wave Detector Gerhard Heinzel and Albrecht Rüdiger, AEI Hannover

  2. Thanks First I would like to convey Gerhard Heinzel‘s regret that he cannot be here today: urgent other commitments My talk will draw to a major extent on Gerhard’s notes Next, I would like to express my thanks for the invitation to come to Beijing for this Third International and First Sino-German ASTROD Symposium, this one again in Beijing as the memorable first one in 2001 It fills me with joy to meet many „old“ friends and colleagues, and to make new acquaintances, and I am again overwhelmed by the friendliness and helpfulness of the organizers

  3. Sequence of talks on LISA, LISA Pathfinder It is unfortunate that my talk on the LISA Pathfinder precedes Oliver Jennrich‘s talk on LISA, to be held tomorrow May I, not to overload my talk with the details of LISA, just assume LISA to be sufficiently known to most of us and plunge into discussing its Technology Demonstrator Tomorrow will then give you the latest news on LISA, from the person most competent on it: Oliver Jennrich

  4. Third International ASTROD Symposium, Beijing 14 July 2006 LISA Pathfinder An ESA-Nasa project to test certain technological aspects of the full-sized LISA GW detector:

  5. Third International ASTROD Symposium, Beijing 14 July 2006 LISA Pathfinder An ESA-Nasa project to test certain technological aspects of the full-sized LISA GW detector: Two free-floating test masses in one spacecraft

  6. Interferometry on LISA Pathfinder: two free-floating test masses Multiple interferometry using heterodyne Mach-Zehnder to measure: relative distance, displacement, relative beam phase, laser frequency

  7. Injection into orbit near L1 Lagrange point with sequence of apogee-raising rocket firings

  8. LISA Pathfinder • After initial study, SMART-2 was descoped and renamed LISA Pathfinder • Darwin Pathfinder removed from mission • Single spacecraft with two payloads: • European provided LTP • NASA provided DRS • Both payloads comprised*: • Two inertial sensors • Laser metrology • Micro-Newton Thrusters • DFACS • Orbit: Lissajous orbit around L1 • Launch Vehicle: Rockot • Launch date: 4th Qtr 2009 *The inertial sensor and laser metrology have now been descoped from the DRS

  9. Mission Goal [1] • The primary goal of LISA Pathfinder is to verify that a test mass can be put in pure gravitational free-fall with residual acceleration noise less than over a frequency range of 1-30mHz

  10. Mission Goal [2] • A secondary goal, which has now become directly relevant to LISA, is to demonstrate laser metrology using free floating mirrors with a displacement sensitivity of over a frequency range of 1-30mHz

  11. Proof Mass • Procured from Heraeus, Germany • 46mm cube of Gold-Platinum • 73% Au:27%Pt • Mass = 1.96kg • Indentation on top and chamfered corners for caging mechanism • Similar to LISA test mass • Magnetic Susceptibility requirement relaxed by one order of magnitude • “A sensitive Torsion Balance for LISA Proof Mass Testing”, Stephen Schlamminger, Tuesday, 16:50 Raw Material Polished Polished and Coated

  12. Inertial Sensor Ground Testing • Inertial sensor cannot be fully tested on ground • Hence the need for LISA Pathfinder • Ground testing focussed on torsion pendulums • Dedicated torsion pendulums constructed at the University of Trento • Noise in torsion pendulum approaching that of LISA Pathfinder!! • Only in one axis • Light-weighted proof mass • Cannot fully represent cross-coupling

  13. Micro-Newton Thrusters • Micro-Newton thrusters for LTP based on Field Emission Electric Propulsion (FEEP) • Two developments underway in Europe • ALTA: Caesium FEEP • ARCS: Indium FEEP • After first phase of development, down-select will be made between the two thruster architectures • This design will be taken to flight hardware

  14. LTP Integration: how it’s put together

  15. LTP Core Assembly

  16. Schütteltest Optische Bank

  17. Launch Vehicle • Baseline launch vehicle: Rockot • Procured from Eurockot, Bremen • Breeze KM upper stage • Proven vehicle with heritage • SS19 ICBM! • Launch from Plesetsk, Russia (latitude 63o) • Injection into 200x900 km orbit • Max lift-off weight of S/C: 1910 kg • Facility to be upgraded for bi-propellant fuelling (vapour traps, waste disposal, etc)

  18. Launch Vehicle • Target launch vehicle is VEGA • Procured from Arianespace • New launcher • LPF could be first flight! • Launch from Kourou, French Guiana (latitude 5o) • Injection into circular orbit…Check • No free injection into L1 Lissajous orbit • Requires injection burn • Winter temperature : ~28oC

  19. Launch Sites Plesetsk: Winter temperature : -30oC! Kourou: Winter temperature : +28oC!

  20. Orbit • LPF launched into high inclination orbit of 200x900km • 15 apogee raising manoeuvers required to deliver LPF to L1 • High inclination orbit allows free transfer (no orbit insertion required) • Prop module separate during transfer phase • Final orbit is Lissajous orbit around L1

  21. Interferometry on LISA Pathfinder: two free-floating test masses Multiple interferometry to measure: relative distance, displacement from OB, relative beam phase, laser frequency

  22. Heterodyne measurement of relative distance

  23. Displacement with respect to optical bench

  24. Interferometry on LISA Pathfinder: two free-floating test masses Multiple interferometry to measure: relative distance, displacement from OB, relative beam phase, laser frequency

  25. Optical Bench EM performance

  26. Phase-meter performance

  27. LPF Status • LPF passed Mission Preliminary Design Review (M-PDR) in February 2006 • M-PDR consolidates the LTP PDR, System PDR, Ground Segment Requirements Review, and DRS CDR LISA Pathfinder is now in PHASE C/D: Detailed Design Phase

  28. LPF Main Reviews/Schedule • System Requirements Review Jun-Nov 2004 • Technology Readiness Review 22 June 2005 • Preliminary Design Review 29 September 2005 • LTP Preliminary Design Review 31 August 2005 • Ground Segment Req Review 24 November 2005 • DRS Delta-CDR/Risk Review 20 January 2006 • Mission Preliminary Design Review 16 February 2006 • LTP Subsys. Critical Design Review Q3-Q4 2006 • LTP Critical Design Review Q1-Q2 2007 • Critical Design Review Q3 2007 • Flight Acceptance Review Q4 2009 • Launch Q4 2009

  29. LTP Team LTP workshop, Trento 2005