LISA R&D

Collaboration:

- Italy: Trento Univ. and INFN , Perugia Univ. and INFN, Firenze Univ. and INFN, Napoli Univ. and INFN, Roma Univ. "Tor Vergata" and INFN, Urbino Univ., ASI.
- ESA
- NASA

National Responsible: S. Vitale (Trento)

Laboratory: Space mission

1. Goal of the experiment

LISA, Laser Interferometer Space Antenna for the detection of Gravitational waves, is a project aimed at placing in a heliocentric orbit, a constellation of three spacecraft acting as a gravitational wave antenna for signals in the frequency range between 0.1 mHz and 0.1 Hz.

More on the experiment…

2.

Activities in 2002

We performed the trade-off procedure for the identification of the electrodes geometry and the construction materials of the capacitive inertial sensor for the LISA Technology Package (LTP) and for LISA. We updated the noise calculation for the read-out electronics configuration.

The detailed design phase of the first inertial sensor engineering model is going to be finalized and construction will begin shortly under our supervision.

The existing torsion pendulum test facility has been upgraded.

A torsion pendulum with the required resonance frequency of 1.8 mHz has been realized together with a magnetic dumper system of the simple mode pendulum oscillation. A Molybdenum-SHAPAL inertial sensor prototype (realized within a previous study, with an electrode configuration similar to the one chosen for the engineering model) has been implemented with a complete 6 channel (one for each degree of freedom of the test mass) breadboard version of the read-out/actuation electronics and has been integrated within the torsion pendulum facility.

Functionality and performances tests of the inertial sensor have been already performed and a number of different tests to probe the capability of the torsion pendulum facility are in progress. We have successfully demonstrated the techniques for measuring the test mass electric charge and magnetic moment. Preliminary measurements of force noise and stiffness are in progress. Up to now, we achieved a stray force sensitivity of about 3x10-13 N/sqrt(Hz) at 1 mHz, just 5 times the expected thermal noise limit.

The first phase of activity devoted to the definition of the architecture of the LISA Technology Package and in particular to the definition of the requirements for all its subsystem and their mode of operation, has been concluded (a full report has been produced, “The LISA Technology Package on board SMART-2”, October 2002).

We performed also a quite extensive analysis, supported with numerical simulations, of magnetic and gravitational effects and their impact both on the design and verification procedure of the LISA Technology Package and the spacecraft.

As a summary, the following achievements have been obtained:

- Final design of the inertial sensor for the demonstration mission SMART2 (100 %)
- Realization of the Engineering Model of the sensor (50 %) (*)
- Validation and test of the parasitic forces (80 %)
- Participation to the architecture of the flight test of the sensor for the SMART2 mission (100 %)

(*) The realization of another prototype, deemed as necessary in order to investigate different configurations and to perform additional tests, was not possible in 2002 because of lack of funding.

Milestones 2003

Set-up LISA WS in progress | March 2003
Interpolation the cosmic-ray primary and solar energy fluxes and choice of simulation protocol (MC- other than GEANT) for the calculation of the charge process of the test masses: preliminary approach | May 2003
Preliminary results of the MC simulation for a LISA simplified geometry | December 2003
Optical sensing and actuation: preliminary studies and concept | November 2003
Optical sensing: preliminary bench top tests | April 2003
Optical sensing: preliminary tests on critical components | November 2003
Design and construction of a second torsion pendulum test facility | December 2003
Design and machining test of critical parts of inertial sensor prototypes | December 2003
Choice of fibers material | March 2003
Development of a first version facility for fiber production | October 2003
Design of a single degree of freedom levitation prototype and analysis of levitation method potential (Technical report) | September 2003
Test report on levitation prototype | December 2003

3. INFN contribution to the experiment in terms of manpower and financial support

Manpower: the group is composed of 34 researchers (16.4 FTE) and 6 technicians (1.9 FTE) associated to INFN.

Budget for the Year 2002: 1.3 % of CSN2 budget for 2003.

4. Number of Publications in refereed journals: 3

5. Conference talks: 15

6. Number of undergraduate and doctoral thesis in the experiment

7. Leadership roles and primary responsibilities in the experiment

- S. Vitale, Member of the core ESA science team
- S. Vitale, Member of the international LISA team (ESA/NASA) and of the Observatory Architecture Team (top scientific design team, 3 european members and 3 american members)

- S. Vitale, Prime contractor ESTEC/Contract #15580/01/NL/HB “The LISA Technology Package on board SMART-2” with the subcontractors: the Albert Einstein Institute (Max Planck Institut für Gravitationsphysik), the University of Hannover , Carlo Gavazzi Space (Italy), the University of Birmingham (UK) the University of Glasgow (UK), the Space Research Organisation Netherland (NL)

- S. Vitale, Subcontractor to Carlo Gavazzi Space (Italy ) as responsible of the technical/scientific coordination within the ESTEC/Contract “Inertial Sensor Definition for LISA”

- S. Vitale, Chair, ESA's Fundamental Physics Advisory Group

- S. Vitale, Member of ESA Space Science Advisory Committee

8. Innovative instruments

Development of a gravitational sensor for LISA.

Development of a torsion pendulum based test bench for parasitic forces.

9. Competing experiments

There are no competing experiments. There is a general consensus that ground based experiments that search for waves in the audio band are complementary to LISA as they look for a rather different kind of gravitational wave sources.

10. International committees that have reviewed the experiment.

LISA has been chosen by ESA's SPC has a cornerstone mission in fundamental physics. Has been confirmed in this status by many external and internal reviews. LISA has been endorsed by a series of panels of the NSF and NASA in the USA.