Demonstration of Time Delay Interferometry and Spacecraft Ranging in a Space-based Gravitational Wave Detector using the UF-LISA Interferometry Simulator

TL;DR

This paper demonstrates the use of the UF-LISA Interferometry Simulator to test and validate Time-Delay Interferometry and spacecraft ranging with nanosecond precision, crucial for space-based gravitational wave detection.

Contribution

It presents the first experimental validation of TDI 2.0 combinations with realistic delays and Doppler shifts using a hardware-in-the-loop simulator.

Findings

Achieved nanosecond accuracy in delay estimation using TDI-ranging reference tone.

Successfully canceled laser frequency noise by 10 orders of magnitude.

Validated TDI techniques under realistic space conditions.

Abstract

Space-based gravitational-wave observatories such as the Laser Interferometer Space Antenna (LISA) use time-shifted and time-scaled linear combinations of differential laser-phase beat signals to cancel the otherwise overwhelming laser frequency noise. Nanosecond timing precision is needed to accurately form these Time-Delay Interferometry (TDI) combinations which defines a ~1 meter requirement on the inter-spacecraft ranging capability. The University of Florida Hardware-in-the-loop LISA Interferometry Simulator (UFLIS) has been used to test Time-Delay Interferometry in a configuration which incorporates variable delays, realistic Doppler shifts, and simulated gravitational-wave signals. The TDI 2.0 combinations are exploited to determine the time-changing delays with nanosecond accuracy using a TDI-ranging reference tone. These variable delays are used in forming the TDI combinations to achieve the LISA interferometry sensitivity resulting from 10 orders of magnitude laser frequency noise cancellation.