Approaching Free Fall on Two Degrees of Freedom: Simultaneous Measurement of Residual Force and Torque on a Double Torsion Pendulum

Year: 2016

Authors: Bassan M., Cavalleri A., De Laurentis M., De Marchi F., De Rosa R., Di Fiore L., Dolesi R., Finetti N., Garufi F., Grado A., Hueller M., Marconi L., Milano L., Pucacco G., Stanga R., Visco M., Vitale S., Weber W.J.

Autors Affiliation: Univ Roma Tor Vergata, Dipartimento Fis, I-00133 Rome, Italy; INFN Sez Roma2, I-00133 Rome, Italy; Fdn Bruno Kessler, CNR Ist Foton & Nanotecnol, I-38123 Povo, TN, Italy; Univ Trento, Dipartimento Fis, I-38050 Povo, TN, Italy; INFN TIFPA, I-38050 Povo, TN, Italy; Univ Naples Federico II, Dipartimento Fis, I-80126 Naples, Italy; INFN Sez Napoli, I-80126 Naples, Italy; Univ Aquila, Dipartimento Sci Fis & Chim, I-67100 Laquila, Italy; INFN Sez Firenze, I-50019 Florence, Italy; INAF Osservatorio Astron Capodimonte, I-80126 Naples, Italy; Univ Florence, Dipartimento Fis & Astron, I-50019 Florence, Italy; INAF Ist Astrofis & Planetol Spaziali, I-00133 Rome, Italy; Univ Rome, Sapienza, DIMA, I-00184 Rome, Italy; INO CNR, I-50125 Florence, Italy.

Abstract: A torsion pendulum with 2 soft degrees of freedom (DOFs), realized by off-axis cascading two torsion fibers, has been built and operated. This instrument helps characterize the geodesic motion of a test mass for LISA Pathfinder or any other free-fall space mission, providing information on cross talk and other effects that cannot be detected when monitoring a single DOF. We show that it is possible to simultaneously measure both the residual force and the residual torque acting on a quasifree test mass. As an example of the investigations that a double pendulum allows, we report the measurement of the force-to-torque cross talk, i.e., the amount of actuation signal, produced by applying a force on the suspended test mass, that leaks into the rotational DOF, detected by measuring the corresponding (unwanted) torque.

Journal/Review: PHYSICAL REVIEW LETTERS

Volume: 116 (5)      Pages from: 51104-1  to: 51104-5

KeyWords: Crosstalk; Degrees of freedom (mechanics); Mechanics; Space probes; Torque; Torsional stress, Actuation signals; Degrees of freedom (DoFs); Double pendulum; LISA Pathfinder; Residual forces; Simultaneous measurement; Torsion pendulum; Two degrees of freedom, Pendulums
DOI: 10.1103/PhysRevLett.116.051104

Citations: 20
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