Precision Metrology for Space Science: LISA, Atom Interferometry, and Optical Clocks

The hardest space-science missions are, at their core, measurement problems. ESA’s LISA gravitational-wave observatory was formally adopted in January 2024, with industrial construction under prime contractor OHB System AG underway since mid-2025, and launch targeted for the mid-to-late 2030s on the Ariane 6 launcher. LISA must resolve picometer-scale changes in distance across 2.5-million-kilometer arms: a fractional measurement of order one part in 10^21. At that level, the spacecraft and instrument form a single coupled measurement system, and the limiting noise sources are precisely the types an analog and measurement engineer worries about on the bench, scaled to extremes. In this talk, we will walk through the LISA metrology chain end-to-end, mapping each link to the noise term it contributes. We will also examine how this metrology cross-pollinates. GRACE Follow-On’s laser ranging interferometer (LRI) demonstrated nanometer precision over 220km and the GRACE-FO mission now maps changes in Earth’s gravity associated with groundwater, ice, oceans, and other redistributed mass. Meanwhile, atom interferometers and portable optical clocks are moving fundamental-physics techniques toward field-deployable inertial sensing, gravity measurement, and relativistic geodesy.

Speaker: Walter Victor Unglaub, CSU Dominguez Hills

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