Clock-jitter reduction in LISA time-delay interferometry combinations

Understand

The Laser Interferometer Space Antenna (LISA) is a European Space Agency mission that aims to measure gravitational waves in the millihertz range.

• The three-spacecraft constellation forms a nearly-equilateral triangle, which experiences flexing along its orbit around the Sun.
• These time-varying and unequal armlengths require to process measurements with time-delay interferometry (TDI) to synthesize virtual equal-arm interferometers, and reduce the otherwise overwhelming laser frequency noise.
• Algorithms compatible with such TDI combinations have recently been proposed in order to suppress the phase fluctuations of the onboard ultra-stable oscillators (USO) used as reference clocks.