Phys. Rev. Lett. 120, 061101 (2018)

In the wake of LIGO’s success, we are now turning to the skies for the next generation of gravitational-wave detectors. LISA, the Laser Interferometer Space Antenna, involves an interferometer comprising three space crafts — each hosting two free-falling test masses that work as the reference bodies at the end of each arm. Detection of gravitational waves requires fine control of the relative acceleration of these masses. Verifying the feasibility of such control has been the objective of the LISA Pathfinder mission, which launched in December 2015 and was completed in June 2017.

Michele Armano and colleagues have now reported the latest figures for the differential acceleration noise measured aboard LISA Pathfinder. The reduction of the residual gas pressure and improvements in the systematics arising from the electrostatic actuation force and the inertial influence of the spacecraft led to noise levels that would in principle allow LISA to detect gravitational waves at frequencies as low as 20 μHz. Such low-frequency waves are emitted by coalescing objects days before the actual event, so we can be well-prepared to detect them in all their glory.