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

2. LISA Pathfinder 6 th International LISA Symposium 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. LISA Pathfinder 6 th International LISA Symposium 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. LISA Pathfinder An ESA-Nasa project to test certain technological aspects of the full-sized LISA GW detector: Third International ASTROD Symposium, Beijing 14 July 2006

5. 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 Third International ASTROD Symposium, Beijing 14 July 2006

6. LISA Pathfinder 6 th International LISA Symposium

7. LISA Pathfinder 6 th International LISA Symposium 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

8. LISA Pathfinder 6 th International LISA Symposium Injection into orbit near L1 Lagrange point with sequence of apogee-raising rocket firings

9. LISA Pathfinder 6 th International LISA Symposium 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: 4 th Qtr 2009 *The inertial sensor and laser metrology have now been descoped from the DRS

10. LISA Pathfinder 6 th International LISA Symposium 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

11. LISA Pathfinder 6 th International LISA Symposium 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

12. LISA Pathfinder 6 th International LISA Symposium 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 and Coated

13. LISA Pathfinder 6 th International LISA Symposium Caging Mechanism Clamp the test-mass in position and sustain launch load –Pre-load = 3000N Break large adhesion created by vibration under load –No lubricants possible –All gold coated surfaces Release the test-mass around the center of the electrode housing with low enough kinetic energy such that proof mass can be electrostatically captured Caging Mechanism procured by Laben (Italy) LPF Caging Mechanism requirements identical to that of LISA –LPF Hardware can be directly transferred to LISA

14. LISA Pathfinder 6 th International LISA Symposium Caging Mechanism High Load Hydraulic Actuator (3000N) Positioning Actuator (100N) Release Actuator (10N)

15. LISA Pathfinder 6 th International LISA Symposium 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

16. LISA Pathfinder 6 th International LISA Symposium 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

17. LISA Pathfinder 6 th International LISA Symposium

18. LISA Pathfinder 6 th International LISA Symposium LTP Integration: how it’s put together

19. LISA Pathfinder 6 th International LISA Symposium

20. LISA Pathfinder 6 th International LISA Symposium

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22. LISA Pathfinder 6 th International LISA Symposium

23. LISA Pathfinder 6 th International LISA Symposium

24. LISA Pathfinder 6 th International LISA Symposium LTP Core Assembly

25. LISA Pathfinder 6 th International LISA Symposium Schütteltest Optische Bank

26. LISA Pathfinder 6 th International LISA Symposium 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 63 o ) –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)

27. LISA Pathfinder 6 th International LISA Symposium Launch Vehicle Target launch vehicle is VEGA –Procured from Arianespace –New launcher LPF could be first flight! –Launch from Kourou, French Guiana (latitude 5 o ) –Injection into circular orbit…Check –No free injection into L1 Lissajous orbit Requires injection burn –Winter temperature : ~28 o C

28. LISA Pathfinder 6 th International LISA Symposium Launch Sites Plesetsk: Winter temperature : -30 o C! Kourou: Winter temperature : +28 o C!

29. LISA Pathfinder 6 th International LISA Symposium 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

30. LISA Pathfinder 6 th International LISA Symposium Interferometry on LISA Pathfinder: two free-floating test masses Multiple interferometry to measure: relative distance, displacement from OB, relative beam phase, laser frequency

31. LISA Pathfinder 6 th International LISA Symposium Heterodyne measurement of relative distance

32. LISA Pathfinder 6 th International LISA Symposium Displacement with respect to optical bench

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34. LISA Pathfinder 6 th International LISA Symposium

35. LISA Pathfinder 6 th International LISA Symposium Interferometry on LISA Pathfinder: two free-floating test masses Multiple interferometry to measure: relative distance, displacement from OB, relative beam phase, laser frequency

36. LISA Pathfinder 6 th International LISA Symposium

37. LISA Pathfinder 6 th International LISA Symposium Optical Bench EM performance

38. LISA Pathfinder 6 th International LISA Symposium Phase-meter performance

39. LISA Pathfinder 6 th International LISA Symposium

40. LISA Pathfinder 6 th International LISA Symposium 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

41. LISA Pathfinder 6 th International LISA Symposium LPF Main Reviews/Schedule System Requirements ReviewJun-Nov 2004 Technology Readiness Review22 June 2005 Preliminary Design Review29 September 2005 LTP Preliminary Design Review31 August 2005 Ground Segment Req Review24 November 2005 DRS Delta-CDR/Risk Review20 January 2006 Mission Preliminary Design Review16 February 2006 LTP Subsys. Critical Design ReviewQ3-Q4 2006 LTP Critical Design ReviewQ1-Q2 2007 Critical Design ReviewQ3 2007 Flight Acceptance ReviewQ4 2009 Launch Q4 2009

42. LISA Pathfinder 6 th International LISA Symposium LTP Team LTP workshop, Trento 2005