LISA R&D
Collaboration:
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.
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:
(*) 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, 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.