Clock Noise Removal in LISA

Abstract

The relative motion of the LISA spacecraft will Doppler shift the laser frequencies by around 15 MHz. These Doppler shifts introduce sensitivity to the phase noise of the measurement's master clock. Using the most stable clocks available this effect would degrade the LISA sensitivity by more than a factor of 100. This clock noise can be removed in post-processing if the clock phase can be transferred between the spacecraft with a fidelity of a few microcycles/Hz. In the LISA baseline design, the clock phase is phase modulated onto the science lasers exchanged between spacecraft. Interference between the outgoing sidebands and the incoming sidebands contains the information necessary to remove the clock noise in post-processing. The details of the LISA clock noise removal scheme are described and results of a recent successful demonstration of the clock noise transfer are presented. Show more