Modulation of LISA free-fall orbits due to the EarthMoon system

Massimo Cerdonio (1) , Fabrizio de Marchi (2) , Roberto de Pietri (3) , Philippe Jetzer (4) , Francesco Marzari (1) , Giulio Mazzolo (5) , Antonello Ortolan (6) , Mauro Sereno (7, 8)

1 Dipartimento di Fisica [Padova]
2 Department of Physics
3 Department of Physics
4 Institute of Theoretical Physics
5 AEI - Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut )
6 INFN Laboratori Nazionali di Legnaro
7 Dipartimento di Fisica
8 Sezione di Torino

We calculate the effect of the Earth-Moon (EM) system on the freefall motion of LISA test masses. We show that the periodic gravitational pulling of the EM system induces a resonance with fundamental frequency 1 yr −1 and a series of periodic perturbations with frequencies equal to integer harmonics of the synodic month (3.92 × 10 −7 Hz). We then evaluate the effects of these perturbations (up to the 6 th harmonics) on the relative motions between each test masses couple, finding that they range between 3 mm and 10 pm for the 2 nd and 6 th harmonic, respectively. If we take the LISA sensitivity curve, as extrapolated down to 10 −6 Hz in [ 1 ], we obtain that a few harmonics of the EM system can be detected in the Doppler data collected by the LISA space mission. This suggests that the EM system gravitational near field could provide an additional crosscheck to the calibration of LISA, as extended to such low frequencies.

Mots clés: Physical Sciences

Massimo Cerdonio, Fabrizio de Marchi, Roberto de Pietri, Philippe Jetzer, Francesco Marzari, et al.. Modulation of LISA free-fall orbits due to the EarthMoon system. Classical and Quantum Gravity, 2010, 27 (16), pp.165007. ⟨10.1088/0264-9381/27/16/165007⟩. ⟨hal-00630000⟩