lisa pathfinder

LISA Pathfinder

A Technology Demonstrator for the

LISA Space Gravitational-Wave Detector

Gerhard Heinzel and Albrecht Rüdiger, AEI Hannover

Third International ASTROD Symposium, Beijing14 July 2006

LISA Pathfinder

6th 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

LISA Pathfinder


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

LISA Pathfinder

An ESA-Nasa project to test certain technological aspects of

the full-sized LISA GW detector:


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


LISA Pathfinder


LISA Pathfinder


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

LISA Pathfinder


Injection into orbit near L1 Lagrange pointwith sequence of apogee-raising rocket firings

LISA Pathfinder


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

LISA Pathfinder


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

HzmsmHz

ffSa

2

2

1421

31103

LISA Pathfinder


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

Hzmf

mHzS x

2

1221 3

1109

LISA Pathfinder


Proof Mass

Procured from Heraeus, Germany46mm cube of Gold-Platinum– 73% Au:27%Pt

Mass = 1.96kgIndentation 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

RawMaterial

Polished

Polished and Coated

LISA Pathfinder


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

LISA Pathfinder


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

LISA Pathfinder


LISA Pathfinder


LTP Integration: how it’s put together

LISA Pathfinder


LISA Pathfinder


LTP Core Assembly

LISA Pathfinder


Schütteltest Optische Bank

LISA Pathfinder


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)

LISA Pathfinder


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

LISA Pathfinder


Launch Sites

Plesetsk:

Winter temperature : -30oC!

Kourou:

Winter temperature : +28oC!

LISA Pathfinder


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

LISA Pathfinder



Multiple interferometry to measure: relative distance, displacement from OB, relative beam phase, laser frequency

LISA Pathfinder


Heterodyne measurement of relative distance

LISA Pathfinder


Displacement with respect to optical bench

LISA Pathfinder


LISA Pathfinder



Multiple interferometry to measure: relative distance, displacement from OB, relative beam phase, laser frequency

LISA Pathfinder


LISA Pathfinder


Optical Bench EM performance

LISA Pathfinder


Phase-meter performance

LISA Pathfinder


LISA Pathfinder


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

LISA Pathfinder


LPF Main Reviews/ScheduleSystem 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

LISA Pathfinder


LTP Team

LTP workshop, Trento 2005

lisa pathfinder

Documents

lisa pathfinderit

details of lisa

fullsized lisa gw detector

frequency range

secondary goal

sinogerman astrod symposium

commitmentsmy talk

certain technological